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RENEWABLE ENERGY - WE PLUG INTO THE SUN!
" I'd put my money on the sun and solar energy. What a source of power! I hope we don't have to wait until oil and coal run out before we tackle that." Thomas Edison to Henry Ford, 1931
ENERGY IS A FORCE THAT DOES SOMETHING.
And we ask a lot from the energies available to us, especially electrical and chemical energies. The electrical energy from the AC power "Grid" is obtained primarily from mined, heavily polluting, nonrenewable resources: coal, petroleum in some form, "natural" (thermogenic and increasingly tapped using highly polluting hydraulic fracturing technology) gas, or highly refined uranium-bearing ore. A tiny portion (in the U.S.) of electrical power is supplied by renewable sources: moving water captured by hydroelectric dams turning turbine-coupled generators, moving air powering large wind turbines, sunlight, (either simply energizing banks of photovoltaic (PV) panels directly or by using mirrors to concentrate the sun's energy on oil-filled pipes that power a steam turbine), and high-temperature, underground, geothermal heat powering steam generators.
EVERY SOURCE OF ENERGY WE HARVEST UTILIZES SOME FORM OF ENERGY CONVERSION.
For instance, heat (thermal energy - matter that is wiggling around frantically) from fuel combustion, nuclear fission, or concentrated sunlight is first converted to mechanical energy, then, finally into electricity. Electricity is the medium of energy transport. And at the end of its travels it usually gets converted into mechanical, chemical, or thermal energy again. Each stage of energy conversion lacks perfect efficiency. There is always a certain percent lost, so keeping the number of conversions, their efficiency, and the transport distance to a minimum gives the best results.
Chemical energy is often utilized solely for its
ability to produce heat, often for a terribly inefficient conversion
(about 24%!) into mechanical energy (the internal combustion gasoline
engine). Chemical energy for portable power, remote locations, or
high volume users is usually supplied by nonrenewable petroleum in the
form of natural gas, liquefied petroleum (LP), gasoline, diesel fuel,
fuel oil, aviation fuel, or kerosene. Really high volume users who don't
need a portable source (like electrical power plants) use coal burning
in a "fluidized bed" burner, at about 44% efficiency.
A hundred years ago the scenario was quite different. Electricity, where it could be obtained, was usually from hydroelectric dams, small local steam engine generators, or, a little later, from small wind turbines. It was stored in bulky, heavy, lead-acid batteries that could be charged, discharged, and recharged many times. Chemical energy for direct heating of homes, or for conversion to mechanical energy was obtained mainly from non-renewable coal or renewable trees.
SOME HISTORICAL PERSPECTIVE
World War II was the impetus for many of the changes we see now. A huge energy appetite and the demands for massive destructive capabilities left us with an enormous civilian chemical products industry and the ability to produce electrical energy from the controlled splitting of uranium atoms. Both industries have left us with huge and ongoing waste disposal problems, neither of which has been adequately resolved. Coal mining continues to be a major polluter of water, a hazard to miners and the living things near the mines, and, even with decreased noxious emissions from planned "FutureGen" plants, its increasing use exacerbates the global warming scenario of trapped carbon dioxide in the atmosphere.
The most recent trend in non-renewables is "natural" gas (thermogenic methane), hailed for its lower carbon content and quick generator start-up as electrical demand surges suddenly. But the decrease in CO2 is often offset by an increase in leaked methane (from well drilling "blow-outs", cracked casings, leaking pipelines, etc.) which is far stronger as a greenhouse gas. The popular press, influenced no doubt by heavy-handed lobbying, is touting the "carbon neutral" benefits of nukes. But the drilling and transport of methane (and the mining and transport of huge quantities of "fracking sand" for this process) and the mining, transport, and extensive preparation of uranium fuel rods are all huge sources of carbon dioxide, not to mention the air and water pollution and health hazards associated with gas drilling and uranium mining.
If choosing an energy source or energy infrastructure were just a matter of what makes sense scientifically, in terms of supply now and in the future, any use of solar energy, whether directly from PV (photovoltaic) panels, solar hot water installations, solar thermal power plants, and even wind-turbines (wind is caused by uneven solar heating) makes the most sense. And from a moral perspective energy production should be distributed, not concentrated and monopolized for profit, location-appropriate, human-scale, and affordable. For us this meant a gradual, pay-as-you-go approach to a solar PV system.
Roughly 76% of all electric power generation goes into building operations! That's about 44% of ALL the energy humans produce. Renewable resources that offer energy with no net CO2 increase are the only intelligent choices in our current situation. But a swelling human population practically guarantees that wise choices won't be made by politicians wanting to remain in office. Still, for those who'd like to take a stab at a semi-sustainable lifestyle, there are some updated versions of the traditional renewable energy sources.
Locally made and distributed electrical power production lost its battle with centralized power way back when Edison's local DC power production scenario was replaced by the Westinghouse-Tesla AC power "Grid". The main reasons for the ascendancy of AC power were the ability to cheaply and easily transform the energy to a high voltage that could be transported long distances with lower energy loss, and the ability to transform it back to a safer low voltage at its point of use. This involved the use of "transformers", which are simply coils of wire, varying in diameter and number of windings, wrapped around a laminated iron core. Modern DC voltage conversion devices using power control "transistors" (which are semiconductor-based, high-speed electrical switches) have made locally produced DC power much more efficient, versatile, practical, safe, reliable, and easily obtained. DC to DC converters can transform nearly any voltage to another, either for transport or use. And sine-wave inverters can produce on-site AC power, for conventional appliances, that's often far less "noisy" or "spiky" than grid power (if they are outfitted with on-board or retro-fitted radio frequency (RF) filters made by their manufacturers - more on this in a bit).
JEREMY RIFKIN'S PROPOSAL: "The Third Industrial Revolution"
The five pillars of the latest new (rich folk's) world model for the next 100 years are:
- The use of renewable energy instead of fossil fuels
- The distribution of the power generation facilities to every home and business
- Storage of the power to allow for the intermittent nature of some renewable energy sources
- Vast improvements to the "power Grid" to make it more widespread, more robust in capacity, and more "intelligent" in terms of energy distribution and local conservation
- A switch to electrically powered vehicles to both use the renewable energy more efficiently and to act as storage sites to be tapped at the will of the Grid's demands
While I agree with Mr. Rifkin on most of his premises, that humans are headed for a financial, energetic, environmental, and societal crash using the Second Industrial Revolution's total reliance on fossil fuel sources, I disagree with his proposals on a few points.
I agree that we need distributed renewable energy for all buildings and vehicles. Where we differ is in our notions of sustainable distribution. Not everyone is rich. Many government sources for funding energy projects are either drying up, will do so in the near future as the economy continues to stagnate, or are only utilized as tax refunds by those already wealthy enough to buy the systems. We cannot all afford to build lavish solar/wind/hydroelectric systems at our homes. It took bold Fedaral moves to create the Grid (REA) and support both large renewable (hydroelectric) and non-renewable (coal, oil and nuclear) through subsidies, taxation, and regulation. It will take equally bold efforts to replace this, and I am not talking about starting more wars for oil.
And Rifkin's "Intergrid" concept works very well with information (on the Internet - which moves tiny packets of low-energy bits across large distances very efficiently), but moving vast quantities of electrical energy over these distances is inefficient, a safety hazard, and an eyesore. Don't even get me started on his idea of distributed manufacturing using 3-D printers; nothing I really want is made from plastic!
REASONS WE THINK THAT CONNECTING A RENEWABLE POWER SOURCE TO THE GRID ARE a) STUPID, b) TOO COSTLY, and c) DANGEROUS:
- The Grid is intended and built for power distribution from areas of large supply to areas of high demand, not storage or the intelligent distribution of small sources.
Grid-intertie does not really use the Grid as a "battery". Sometimes you produce an excess, if your system is sufficiently sized, and sometimes you just end up burning coal, oil, "natural" gas, or neutrons (nuclear fission) like everyone else who is not producing power.
If the Grid blacks out, so does your supply of renewable energy, unless you maintain some local storage.
That black-out is for the safety of maintenance staff who need to work on faults in the distribution lines, and it cannot be avoided for the convenience of individual small energy producers.
The Grid inter-tie inverter, local transformer, and the Grid line losses incurred in moving your expensively-produced power around make the system quite inefficient.
Larisa says that Grid inter-tie is like bicycling with training wheels: You don't get the real experience of renewable energy; instead, you get accustomed to the "crutch", and you don't have full control of the process.
- The amount you have to pay for just being Grid-connected (your "base rate") may easily exceed the payments you can get for your excess energy.
Connecting with the Grid is often an "all-or-nothing" decision in terms of equipment purchases and contracts, unless your discretionary funds are ample.
You have to supply liability insurance to make sure you don't inadvertently electrocute any line workers and there are usually up-front fees for the right to become a producer.
Grid inter-tie inverters themselves can be more costly, not to mention the other needed equipment such as added disconnects, meters, etc.
Many utility companies really do not want you to become a producer simply because, if your system is below a certain production threshold, they have to pay you retail prices for power they could buy elsewhere at a wholesale price.
- Connecting to a 7000-volt+ AC supply is always more dangerous than a lower-voltage AC or low-voltage DC source.
Your Grid-intertie inverter injects stress-causing harmonic "switching frequencies" into all of your neighbor's homes. This is listed as "harmonic distortion" in the inverter specs, and it ranges from 2% -10% of the output power.
You come to expect unlimited power, have little impetus for conservation, and the responsibility for your over-consumption, as well as others', is spread throughout the Grid instead of being yours or theirs alone. In a shared power scheme "the biggest hog always feeds first".
THE DECENTRALIZED RENEWABLE HOME POWER SYSTEM:
- Uses a safe, high-capacity, recyclable storage medium on-site.
- It is your insurance against black-outs.
- It has extremely
high efficiency: low line loss, no transformer loss, and no inverter
loss on low-voltage loads running on DC straight from the batteries.
- It requires only a regular homeowner's insurance policy, if any.
- The investment is made "up-front" with no increasingly large "power rental" costs each month.
- Any electrical inverter "noise", when you actually need to use AC loads, remains in your home and can be filtered out on-site.
- You gain a better sense of your power limits and usage, and how to more effectively conserve power.
responsibility for the total environmental cost of your system and its
use lies only with you and the makers of your equipment.
- Solar PV in particular is modular by nature; you can add to it or change it gradually as your needs and budget change.
Home Power Systems can be categorized along a continuum of independent and distributed to dependent and networked, starting with:
- Off-Grid, powered by renewable energy only.
- Smaller off-Grid system with generator back-up power.
- Smaller off-Grid system with the Grid as a parallel system for large loads, or for back-up charging only.
- Grid-intertie, using the Grid as an energy "bank", where your cleanly produced power gets used primarily by energy-hog neighbors who have not made the investment in renewable energy.
- Grid power alone.
We have gotten some recent feedback (at a local introductory PV workshop) indicating that some large power users object to our use of the term "crutch" when describing the Grid or a fossil-fueled generator when powering very large loads. A crutch is just another tool, but it is made for temporary use in special circumstances, not as something you would choose to rely on permanently. If a renewably powered household energy system is not yet big enough to run a shop, farm, or power hungry home-based business, then this crutch may be a temporary necessity. But money spent on fossil fuel, generating infrastructure, or more Grid-sourced power is money that could have been spent to upgrade a renewable power system.
Are you trying to use decentralized renewable power or centralized non-renewable power? If you do not like something, do not feed it. If you want to achieve change, do not hamper it. Indecision is, in itself, a decision if you do not like your present habits. We find that it is best to do what makes you proud of your actions, not just what makes the most economic sense in the narrow, changing confines of your current personal budget. Renewable energy can be done incrementally. Each step is one in the right direction.
You may have noticed that when I refer to the Distributed AC Power Grid I always capitalize the word "Grid". This is intentional, just as it is conventional practice to capitalize the word "God". The reason I do so is that people generally treat the Grid as they would a god, something unknown, unseen, all-powerful, omnipresent, infinitely good, and not-to-be-questioned.
Renewable energy, on the other hand, is something that is best known well if you intend to use it, is definitely seen when it is present, is limited in its power, is present to a lesser extent (for now, anyway), is realistically good (with some ecological footprints in terms of production resources, siting, wildlife impact, etc.), and is certainly not beyond question in terms of practicality for every situation.
Before you start to tackle a renewable power system, if you would like to know a lot more about electricity and its effects on the human body, check out our EMF Hazards page.
OUR HOME POWER SYSTEM - AN HISTORICAL PROGRESSION: (Photovoltaic Solar with Battery Storage - "Off Grid")
When we discuss renewable energy with people it seems that we are usually talking past each other. We started with nothing and built a system from the ground up, meeting our needs as they increased. Most folks nearby already have unlimited Grid power, are supplying "needs" that we long ago decided were not sustainable, have little to no interest in reducing their energy consumption, and simply want us to tell them A) how much to spend, B) what to buy in order to make their super-sized lifestyle ecological, and C) how quickly will they pay for the system in energy savings. If you are "made of money" then this might work for you, but we consider it a case of "dollars over sense".
Our first home electrical energy system, in 1983, was a retrofit on a normal 120-volt AC home electrical system. It was based on the battery in a 1968 Volkswagon (VW) "Bug". Our little 1950's vintage, 8-foot by 35-foot "mobile home" had standard 120-volt wiring but we were in a location nowhere near the Grid's power lines. Our only electrical loads were a small 12-volt TV and a few 12-volt fluorescent lights. We constructed an electrical "umbilical cord" that ran from the VW's battery to our home's electrical fuse box, using the existing 120-volt wiring and outlet boxes for our tiny DC loads. Running from just the Bug's battery, we managed to ration power out for a week before we would have to push-start the car and take a shopping trip 10 miles to the nearest town. This charged the battery for the next week. It also slowly destroyed a battery not designed for deep discharges. A new system was eventually needed.
We next purchased 36 round, 4-inch, silicon solar cells from an electrical surplus catalog. We mounted them to an aluminum sheet using silicone cement and wired all of the cells in electrical series (positive to negative terminals). They were covered by a simple wooden frame with an acrylic cover to keep the rain off. This homemade photovoltaic (PV) panel was not terribly powerful but it worked well! We wired this through a diode to keep the power from flowing backward at night, and wired it all to a new, deep-cycle marine battery. This did a much better job of supplying our meager needs, and we still could connect the car if we had a lot of cloudy weather that precluded solar charging.
Every home power system we have used since that time simply added more loads, more and better wiring, more power storage, more switching and circuit protection, more jobs done using solar or wind power, and more sources of renewable power generation. Some folks have asked why we ended up with PV panels mounted in different places and on various racks around our house. Partly this is because we added panels over time and partly it is because the best solar site nearest our house (to keep wire costs to a minimum) has enough trees surrounding it that space for more panels was limited. We wanted the closest possible site because we had a simple 12-volt charge controller that did not convert high voltages to lower ones for our battery bank as our current controller does. This meant that we needed thick, expensive copper wire. The site south of our house gets sun from mid-morning until nearly sunset and is faced directly south. The site next to our driveway, with three panels, gets sun immediately in the morning but loses it mid-to-late afternoon so it is faced slightly south east. The single panel on our shed originally just charged a DC electric lawnmower and it also faces south-east. More details follow below.
So how do you decide what size your power system needs to be? You probably don't want to begin where we did, but your first step may be a single PV panel hooked up to a few lights and a battery or maybe a "micro-inverter" designed to connect your PV to the power grid. One place to start is by using a solar calculator.
Or, if you are undecided about which type of renewable energy might be best for you location, situation, and funding, you can click here see a flow chart PDF that logically explains how we go about designing a renewable energy system.
The first questions you need to ask yourself are:
- What forms of renewable energy are available for harvesting locally? Wind, sunshine, running water?
- How much energy do I really need for the various things I'm trying to accomplish?
- What form does that energy need to be in (heat, lighting, water pumping, hot water, cooking heat, etc.)?
- How can I reduce both my use of energy and, especially, my use of non-renewables?
- Am I just going to use renewables in a new installation or should I switch from an existing Grid connection to renewables a bit at a time using separate electrical panels and circuits?
- How can I afford this and where do I start?
Some will certainly first ask "Is this renewable stuff cost-effective?", or "What is the pay-back period?", or simply "Isn't this awfully expensive"? Of course it's expensive. You are buying you power up-front instead of "renting" it a month at a time. We went with solar energy since it was the the best for our area and our home-site. And since solar systems are "modular", you don't have to buy enough for all of your electrical needs at one time. You can add to it bit-by-bit until you are fully weaned from non-renewable sources. In our case, we started with just one little home-constructed solar panel charging the battery in our VW "Bug". We added to the system and replaced undersized parts as we added more renewably-powered loads. If you'd like more details on how to plan, build, and maintain such a system, I'd suggest reading our book, "Peoples Power Primer - Renewable Energy for the Technically Timid", found on our home page.
This is a quick sketch I made of how the 2013 version of our electrical power system is wired. This is actually two solar systems set up to either charge various outdoor items and the house separately, or all the power can go to the house if necessary. As you can see there has been a lot of evolution over the 30-plus years since the VW Bug system, both in input power and the loads we charge!!
Power flows from the 12-panel photovoltaic (PV) array at the south side of our home in 2 discrete paths. One path, wired with two 12-volt PV panels in series, travels directly to our storage shed where it can help to charge our electric tractor, electric car, and electric hybrid trikes. The highest that voltage can reach is about 42 volts, and the voltage at which the power flow is at its highest (the maximum power point, or MPP) is around 35 volts. So a 36-volt battery can be plugged directly into this wiring without a series charge controller (to limit voltage). This self-limiting charge is really handy for lithium batteries and lead-acid gel cells which much be charged below a specific voltage. The car and tractor usually are charged at a higher voltage, requiring more panels.
These two panels can also feed into an Outback FlexMax-60 MPPT charge controller, where their voltage can be combined with a PV panel on the shed and with 4 series-wired PV panels nearby. These six combined panels can produce up to 900 watts to charge either the electric vehicles and devices in the shed or they can supplement the panels in front of our house, charging the house's battery bank.
The other path from the large PV panel rack goes to an Outback FlexMax-80 MPPT charge controller in the house, regulating power from 10 PV panels wired with 5 series panels in each parallel "stack". With our 12-volt household battery bank this is all the power the controller can handle, about 1200 watts.
Either the big inverter on the electric tractor or our household inverter can run a 144-volt, 10-amp, on-board charger in the car, or we can direct-DC charge it from the PV panels at 48 volts. Sometimes the household inverter is used to run the car's battery heaters in the winter, protecting them from freezing when temperatures get down to -20F.
We also have a single 12-volt PV panel at the shed which can directly charge our little Toro electric lawnmower (to mow garden paths), trickle-charge our house, or it can be switched in series with the other panels leading to the shed. Loads of flexibility!
This is what the DC charge selection switch looked like in our shed before 2012. The top meter shows how many volts are available from the three PV panels that are not pumping power into our house.
Using the switch at the bottom right, we chose to utilize either one 12-volt PV panel to charge our 16-inch Toro mower, "36 volts" (24 nominally, 40 at the most) from two PV panels to charge our hybrid human-electric trikes or trickle-charge our G.E. Elec-Trak tractor, or "48 volts" (36 nominally, 60 at the most) to quick-charge the tractor or charge the Porsche electric car.
When the voltage was set we just plugged the proper cord into the appropriate device and flipped either the left or right breaker switch.
The bottom meter showed the amps flowing into the device, just to confirm that it was charging. And each breaker was wired with a diode to prevent electricity back-flowing from the batteries to the panels at night.
It looks complicated but we just used a device, plugged it into the switch box, and recharged it. If the house was fully charged and we wanted to boost the charge rate into the tractor or car, we switched the house's charge controller to add the power of the ten PV panels that normally just charge the house system.
And this is what the shed wiring looks like in 2013, with the addition of an Outback FlexMax-60 MPPT charge controller and three more Kyocera 135-watt PV panels. The box above was rewired a bit and more Square-D, QO-series AC/DC circuit breakers were added to ease the switching of power to different vehicles and devices. The power of 3, 4, 5, or all 6 non-house-specific PV panels can be sent to the charge controller, where their combined voltages can easily be switched to whatever output voltage is required using the controller's LCD screen and programming buttons.
The electrical boxes at the right control the outputs to either the electric tractor, the electric car, or the house. The box under the black-colored charge controller is used to switch the PV panel inputs to the controller. All sources and loads are switched and protected from overloads using inexpensive, off-the-shelf circuit breakers.
Besides allowing for faster charging of vehicles, the new parallel PV systems allow us to have a good charge rate in the house even when the weather is quite cloudy. We had always used "load management" to cut back on power hungry activities when the sun wasn't strong; now we can do more, still without the need for a non-renewable "back-up" power source.
The following photos and discussion can be downloaded as a PDF file.
OUR HOME POWER SYSTEM:
Power can be stored on-site using a variety of battery chemistries including the old lead-acid, deep-cycling variety, improved by better construction, lower maintenance, and longer useful life before recycling. We once used four, 375 amp-hour, 6-volt batteries wired in series-parallel configuration to obtain 12 volts and 750 amp-hours. Our previous batteries were Thomas Edison's nickel-iron (Ni-Fe) cells using potassium hydroxide electrolyte, manufactured in the 1920's. They were built for severe conditions and industrial use, and could be restored by simply changing electrolyte every 10 years. But we switched to lead-acid mainly because it's getting harder to find replacements for mechanically damaged Ni-Fe cells or to find additional cells. There are Chinese models made now, but the quality is not up to Edison's standards!
Power that exceeds what you can economically store must be either "dumped", "blocked", or "diverted". A charge controller usually blocks excess power input. But some models allow the use of a "grid intertie", a "dump load" or a "divert load". Connecting to the grid is not our preferred choice. But the latter two are types of appliances that "burn off" excess power while doing something useful. If you burn natural gas or propane (LP) to heat water, heat your home, or cook a meal, a charge controller can automatically switch on electrical versions of these loads for you. This allows you to have enough generating power to keep up with electrical demand even on cloudy or windless days. And it gives you the option to power loads that would normally burn fuels.
Actually, as of January, 2011, we now have a replacement battery system that was initially set up in parallel with our older one, as you can see in the photo. The new gray-cased batteries, with two levels of 5 batteries, 10 in all, are sealed lead-acid gel cells made by Deka. We purchased them locally at that time since we heard that the price of lead was about to increase 50% and since our current batteries were over 6 years old. The old wet-cell lead-acids, at the left, typically get up to 10 years of cycling at the rate we use energy while the sealed batteries should at least double that lifespan.
They cost a bit more per amp-hour than equivalent wet cells but, besides the increased "cycle-life", you don't need to add water, vent explosive gases, or worry about corrosion of the terminals or leakage of the cases. They also have a much slower "self-discharge" rate and they don't have to be charged immediately after discharge since they won't "sulfate" like a wet cell (sulfation is the growth of large, insoluble lead sulfate crystals on the battery plates, gradually lowering amp-hour capacity).
The new and old battery sets have a slightly different resting voltage. The wet cells coast at 2.1 volts per cell, or about 12.6 volts as we have them set up. The sealed batteries coast at over 12.8 volts. So while we used both sets we had switches on the main positive terminals of both battery sets, allowing us to run from one or the other. The "wet-cell" battery bank held about 9.4 kWHrs of power and the sealed bank holds about 12.5 kWHrs. Beginning January 1, 2011, the older wet cells were recycled and we now rely solely on the new gel cells.
SIZING YOUR STORAGE
Once you have completed an Electrical Loads Worksheet to determine how many amp-hours of power you will typically need per day you can begin to assess your ideal battery bank size.
Amp-hours/day X Number of days you wish to store X Factor for battery type (X2 for lead-acid cells, or X1.1 for nickel-based cells) X Average battery room temperature factor (80F = 1.0, 70F = 1.04, 60F = 1.11, 50F = 1.19, 40F = 1.30, 30F = 1.40) / Available cell or battery amp-hours = Number of parallel cells or batteries (round up to whole number).
System voltage (12-volts, 24, 36, or 48) / cell or battery voltage = Number or cells or batteries in series (round up to whole number) X Number of parallel cells or batteries (from calculation in previous paragraph) = Number of cells or batteries to buy.
This may seem complicated but it gets you into the right zone in terms of storage size. If you end up with too much storage your batteries may not charge as efficiently as possible and you can simply add more renewably-sourced input, a back-up generator, or Grid back-up charging. If you end up with too little storage you can add more or use the next power-using option.
In our area of the U.S. we typically see about half sunny days and half cloudy, averaged throughout the year. So we eventually built a PV system with about twice as many panels as we would need based solely on our typical usage. What to do with the excess on sunny days?
This is a 300-watt, 0.5-ohm, 12-volt air heating resistor element made by Ohmite. Putting two or more of these in parallel gives you enough heat to make your own oven, which is what we have just done. We often find that our masonry stove gets our water quite hot enough in the winter without additional solar energy, and we need to either use the excess for something like cooking, baking, or charging some other battery-powered device or the controller will simply reduce our solar input electronically, "wasting" valuable sunshine. If you'd like to see the details of what we built, just check near the bottom of our "Eat Local Year-Round" page. In the summer of 2011 we swapped two of these resistors for 5-ohm units which produce only 30 watts of heat at 12 volts. We found that we rarely needed 1200 watts, but using one 30-watt element makes the oven into a great incubator for yogurt or tempeh production. 60 watts gets it a little hotter. And switching the 300-watt units on turns it back into an oven. Lots of flexibility again!
Thinking about where to send excess power brings to mind the notion of figuring out what you need electrical power for at all. In an age where oxen bred more oxen, the idea of switching to a high-priced tractor could seem pretty stupid. But, in an era when solar panels are manufactured mainly via robotics in a factory powered by solar panels, perhaps we've come full-circle. The main thing is to not get hung up on the devices used to fulfill your needs. It's not about the gadgets, it's about the energy source that you have available and how best to harvest it. Or as writer/blogger Sharon Astyk would say, don't "confuse a desire for familiarity with necessity". For instance, if you have always used a clothes dryer, don't presume that it is the only way to achieve dry clothing. A clothesline saves gobs of money when purchasing solar hardware!
Some of what is now used for home energy systems got its start in the military. This is a close-up of the water-saving battery caps we used on our lead-acid "wet-cell" batteries. Since charging batteries "gas off" some hydrogen and oxygen when they're nearing full charge, various caps have been designed to catalytically recombine the gases to water (HydroCaps, for instance), or simply to condense evaporating water (like these), in systems that don't heavily overcharge. This technology was originally used in WWII submarines which surfaced to quickly diesel-charge their batteries and generated lots of explosive gases in the process.
Our sealed lead-acid batteries combine the gases internally and are charged at a lower voltage to prevent very much gassing, all of which means no dangerous gases released in the house and no loss of water that had to periodically be replaced.
We also used a device designed for the military called a "desulfator". It uses a tiny bit of battery power to send a small high-frequency pulse back into "wet-cell" batteries, hampering the growth of large lead sulfate crystals that build up on the lead plates, eventually leading to premature battery failure. This rather cramped photo shows the 2-inch by 2-inch device. We are not using this, nor is it necessary, on the new gel-cell batteries, as they do not sulfate. It is now connected to the wet-cell, lead-acid batteries in our electric tractor.
CENTRALIZED VERSUS DISTRIBUTED SYSTEMS
On-site power generation using wind turbines, micro-hydroelectric, or PV panels is becoming increasingly popular, especially where you can sell excess power to the AC grid, or, even better, when you can remain off-grid and utilize your excess electrical production for heating, cooling, or whatever else makes sense in terms of swapping solar power for LP gas, natural gas, grid electricity, or petroleum that you are now using.
Personally, we prefer not to be grid connected. With monthly connection fees exceeding the cost of the power we actually use, it makes no economic sense for us to support this otherwise ugly, dangerous and innefficient infrastructure. And calling the Grid a giant battery is simply nonsense. The Grid exists to generate and distribute, not store. A temporary excess of wind or sunshine may make your meter spin in reverse and make you feel like a hero, but that power usually goes into the Grid when it's not really needed, gets wasted as heat in the power lines, or goes to the nearest big energy hog who really doesn't care where the power came from.
OUR SOLAR POWER PLANT
Our previous home used both wind and solar electricity, while the current house is solely solar powered. While solar's up-front cost may be the highest of the available alternatives in terms of cost per watt produced, it's the simplest to install, the longest lasting, and the easiest and cheapest to maintain. You can install it in "blocks", adding more capacity as you can afford it. Plus, our current site is ideal for solar but not the others, and you have to use what your site dictates! These were once our sole electric power source: 840 watts of solar power by Kyocera, one of the oldest ceramics companies (and they aren't owned by an oil company!).
We have upgraded to 1900+ watts of solar in order to more quickly charge an electric car conversion of a 1979 Porsche 924. To see the technical specifications on these panels, just Click Here. And to compare specifications of most of the currently available commercial PV panels, just click here for SolarDesignTool.com's comparison page. And to see how many fully cloudy days per year you will need to plan for, just click here for a map of the U.S. Annual Mean Cloudy Days.
Note that we have mounted these panels on a simple, home-built steel pipe rack that is very close to the ground. While some locations may have a security problem with a ground-mount rack and might prefer roof mounting, we live in a rural area far from the road and typically see lots of snow in the winter. Brushing snow from a ground rack is by far easier and safer than climbing to a roof. And the ability to remove snow can be the difference between no power input or full input!
Seen from the back of the panels, the center three panels could be switched to either power the house or charge our G.E. Electrak garden tractor, our cordless electric mower and string trimmer, or our electric-human hybrid trikes (seen on the Transportation Option page). These panels have now been reconfigured on sturdier racks, including 5 more panels (see below). And we can now charge our electric Porsche directly from 6 panels using DC charging instead of the car's on-board AC charger (more efficiently and quickly).
This is a close-up of the PV panel switch arrangement that was once mounted near the PV panels, with the weather cover open. Each toggle controlled one panel using a Double-Pole, Center-Off, 20-Amp DC switch. Toggling up ran the three 12-Volt panels in series to run 36-Volt (60 volts peak) power to the electric tractor and electric-assisted trike. Toggling down put the panels in parallel to run 12-Volt power to the house. This has since been eliminated.
Actually, as of late July 2012, this is part of our latest PV array. There are now 16 Kyocera panels. The oldest, a KC-120, is from 1997. The newest 3 are KD-135's, made in 2011. Four of the panels are not shown since they are mounted on a different building. You can tell the newer panels by their darker blue color, indicating lower reflection of sunlight and more conversion to electricity. These are now wired as two banks with 5 panels in series, leaving up to 6 panels wired in series that run directly up to the shed where they are regulated by an Outback Flexmax-60 charge controller (more on this below), charging either the house, electric tractor, electric car, the hybrid electric trikes, and/or a lawnmower for garden paths.
Some folks have asked us why we used these multi-crystal silicon panels. The single-crystal panels are slightly more efficient, meaning the panels can be a bit smaller for the same power output. But this comes with a higher cost. Amorphous silicon panels are cheaper, flexible, and have slightly better output in cloudy weather. But they are about half as efficient (meaning more space required) and have poor longevity. CIGS panels (made from Copper, Indium, Gallium, and Selenium) are cheaper to produce and have good efficiency. But they are about the same price and are relative newcomers. We chose what works well, has a terrific warranty, and was within our means.
No matter which panels you choose, do not be fooled by some of the outrageous claims made for a certain type of panel. I was once asked if it was true that a bullet or drill could punch a hole in an amorphous panel and the only loss would be a power drop proportional to the area of panel removed. False! Just like a leaf sitting on part of an individual 1/2-volt solar cell, the removed area would limit the entire amp output of ALL the cells wired in series to make up a 12-volt (about 20 volts with no electrical load on it) panel.
Before flowing into the batteries the solar power gets intercepted by this device, a lightning arrestor. It connects to both the positive and negative wires, and shorts to a ground cable if voltage spikes too high.
PRIMITIVE POWER CONTROL
The next item in the positive wire is a simple diode on a heat sink. This one-way electrical valve prevents energy from flowing outward from the batteries to the solar panels at night. This has actually been omitted since a new charge controller, the Outback FlexMax-80, has replaced its functions (see below).
MORE SOPHISTICATED POWER CONTROL
the power then flows into this DC electrical service box. The left breaker cuts off the batteries. The next controls our present Load Diversion Controller (a Trace C-30, seen below). The next controls the solar input. And the final two run the two DC load circuits in our house. We don't use a non-renewable generator for backup power and didn't do so in our previous home either. The solar system is sized to ensure a 2 week supply of electrical power with no solar input. On the worst cloudy days, we still get one-tenth normal power input and an average of half of our days are cloudy. So designing with these factors in mind, we normally have far too much power.
To see a free Adobe PDF file of our household loads, just Click Here.
As of February, 2011, we have switched all of our lighting to 12-volt LEDs (light emitting diodes) in order to further cut our power consumption.
This is an amp-hour meter. It functions as a battery fuel guage. And even though it consumes a tiny bit of power, and injects a "whiney", high pitched, electrical noise frequency into the batteries, it's still worth its cost (about $200) for peace of mind, especially when you're just starting out in renewables and don't yet have a handle on your power usage vs. input.
Most solar controllers shut the PV input off when the batteries are fully charged, or, if you are Grid-connected, excess power is sent into the Grid during sunny days and purchased back from non-renewable sources at night. Instead, we have been using a load diversion controller (Trace C-30) which channels excess power into an "off the shelf" hot water heater and a small chest-type refrigerator. Refrigeration isn't a huge priority in our home since we're not meat or dairy eaters. Still, we do occasionally have left-overs or home-canned condiments that need cooling. This device was replaced by a controller from Outback, the FlaxMax-80 (see below). It does something called Maximum Power Point Tracking, where excess voltage from the panels is turned into more amps flowing into the batteries.
This is our previous load diversion controller. It uses PWM, or Pulse-Width Modulation, to divert the exact amount of excessive input power that will keep the batteries at a specified bulk-charge or float-charge voltage. But with precision came a nasty low-pitched electrical hum from the pulsed DC current sent to the diversion loads. Eventually this had to go in favor of the older C-30 (above), and the house got quieter both in terms of sound and electric fields.
This is the previously mentioned Outback FlexMax-80 MPPT charge controller. It replaces all of the functions of a reverse-flow-preventing diode (seen above), a load diversion controller (like the Trace C-30), and a PWM input controller (like the Trace C-40). It also checks the incoming voltage and continuously converts extra voltage into added amps, yielding up to 30% more power from the same panels!
It can handle up to 80 amps of power and has "AUX Send" output terminals to switch external power-control relays on or off at specific voltages. This allows tight control over our power diversion loads, including the water heater, refrigerator, electric tractor, electric mower, electric hybrid trikes and, most recently, an electric car and electric oven.
Plus, this unit logs all of the voltage, amperage, and power statistics generated by the PV system, available for viewing up to 128 days later. And, since it can handle many different output voltages, it can be switched to charge either our 12-volt household battery bank, our 48-volt electric Porsche (actually 144-volt, but divided into three parallel 48-volt banks for DC charging), and the 36-volt electric tractor (but not at the same time). To see the manual on this product, just Click Here.
ANOTHER IMPORTANT DIVERT LOAD
This photo shows the little wood-covered, and heavily insulated, 10-gallon water heater tank suspended behind the masonry woodstove, where the water can be heated using a spiral of copper pipe around the stove's chimney or by the electric heating element. The stainless steel, 12/24-volt heating element which we purchased to replace the 120-volt element in the water heater can be purchased, among other sources, at Backwoods Solar Electric Systems.
Since neither the Trace C-30 nor the Outback FlexMax-60/80 has large enough internal relays to control the diversion of the 25-62 amps of excess PV power typically used by the water heater, oven, and refrigerator, we use three tiny 12-volt, 40-Amp relays to switch the power. All are now controlled by the auxiliary relay output on the Outback FM-80 controller.
These relays divert excess solar into three very useful assets! Although the refrigerator can run using 120-volt AC or LP gas, we just use the 12-volt DC option, straight from the batteries and solar system. When the battery voltage exceeds 14.1 volts, the loads are on. When voltage drops to 12.8 volts, they turn off. This gives us a 30% "duty cycle" yielding cooled foods without freezing anything, cooked food when we want it, and hot water without boiling it.
INVERTERS - CONVERTING DC TO AC
Our "critical" electrical devices (water pump, lighting, flour mill, radio) run directly from the batteries on 12-volt DC. Conventional 120 volt appliances run from this Exeltech XP1100 Inverter. Since humans are quite sensitive to AC electrical currents, the inverter is switched on only when AC loads are being operated. We use switched outlets at each appliance location and where a device uses a "black box" or "wall wart" to change voltage or switch from AC to DC current, we use additional labeled wall switches to activate only the intended device. This eliminates "phantom loads", which are energy sucking, unintended drains on an otherwise intentional, clean, and efficient electrical system. This inverter easily handled all of our household loads but was too small to use with our electric chainsaw or our electric car charger. For these we used a much larger (but cheaper, $717 on the Web) "modified-sine-wave" inverter (Tripp-Lite APS3636VR) mounted on the electric tractor. We eventually replaced the Exeltech with the model seen below.
Since early 2011 this is our latest household inverter. We traded up from the 1100-watt Exeltch to the 1800-watt Statpower (now Xantrex) unit so that we could operate full 15-amp AC loads, such as our Makita electric chainsaw or our electric car's on-board charger. Although this unit has no built-in filter to remove harmonic switching frequencies it can be used with capacitive filters, such as the Stetzerizer (see below).
WHAT WE DO WITH THE POWER AND HOW WE USE LESS ENERGY:
Many homes that utilize RENEWABLE ENERGY for their electrical needs are wired for both low-voltage DC and standard AC loads. Since electric fields drop as voltage goes down, 12-volt lighting and appliances are an attractive option where low-power, low-amperage devices can be used. In high-amp loads like big motors or water heaters, the increased magnetic fields can offset any gains made from lowering voltage, unless those loads are far from the main living spaces. In our home, all of the lighting is 12-volt DC, although we have a few 12-volt compact fluorescent lamps (CFLs) that convert 12 volts of DC to roughly 10,000 volts of AC in the bulb's "ballast". This creates a moderately-sized electric field "no-man's-land" around the fixtures as a trade-off for one-fifth the energy use. For more detail, check the EMF Hazards page.
We have also started to use 12-volt LED (light-emitting diode) bulbs for all of our lighting. If you can find the ones with the Philips Luxeon, Cree, or Edison Opto-engine LED bulbs, they also put out a lot of light for very little power use. If not, the clustered single-LED bulbs work well too if you can find ones that are bright enough and have a color temperature you can stand. We use mellow, "warm white" bulbs while many of the LEDs out there are the more harsh, but brighter, "cool-white" types. The "light engine" type bulbs have to dissipate a lot of very localized energy to preserve the life of their big LED surfaces so they have aluminum heat-dissipating fins. Our favorite living room task lights draws only 4 watts but put out the equivalent of 40 incandescent-bulb watts at 3000 K ("warm white"). There is no AC electric field to contend with, no inverter "noise", and it puts out less heat than a comparable CFL.
We have recently found (after 2 years of searching) an online source (Energy Efficient Products) for both 110-volt and 12-volt bulbs in Rome, New York that has very low prices, along with pretty good service, documentation, shipping, and responsiveness to its customers. Although we use the 12-volt bulbs, and still recommend their generally problem-free AC models, some of our 12-volt friends have have had problems with a few of the lowest-wattage models causing interference with their FM radios and televisions. If you order bulbs from them be certain that they cause no interference within 15 days or they may not replace/refund your order!
Another factor that can reduce or eliminate AC electric/magnetic field exposure is the "sensible" use of an INVERTER in renewably-powered homes. If the home IS NOT connected to the GRID (by using a GRID-INTERTIE INVERTER), the "stand-alone" inverter turns low-voltage DC from storage batteries into "line-voltage" AC for standard appliances. Since many AC loads can be eliminated by using DC devices wherever possible, the inverter often doesn't have to be running all of the time! And if an inverter should break down (unlikely, but there's always a lightning strike!), powering essential loads direct from battery DC is great insurance.
Older and cheaper "square-wave" and "modified sine-wave" inverters rapidly and abruptly switch voltage levels to create a "choppy" sort of AC that only roughly approximates grid-produced AC. The modern "sine-wave" inverter produces a smoother, wave-like pattern of increasing and decreasing AC voltage that most electrical devices prefer. Not only do motors run cooler on sine waves, but the transformers found in many audio-visual devices and "wall warts" no longer hum. Sine-wave inverters can (at least with some modification) actually produce "cleaner" power than what's found on the grid. Grid-produced AC often has voltage spikes, or dips (requiring the use of surge suppressors) and high-frequency "harmonics" (or "hash") and "transients" (or "spikes") that have additional negative health consequences.
But even the best sine-wave inverters also generate harmonic frequencies and internally-generated switching frequencies. What to do about it? Some inverters constantly check for switched-on loads and turn themselves on only when called for (the Search Mode). And in our home, each cluster of AC outlets has an inverter switch to turn the AC power on only when it's needed. Either way, this eliminates inadvertent AC electric field exposure since no AC is being sent through the wiring most of the time. The Stetzerizer Filters I mention on the EMF Hazards page don't work well on some inverters. A few inverters that seem to be unbothered by the capacitive filtration of the Stetzer filters are the Xantrex (or Statpower) Pro-Sine series, the Xantrex SW series, and the full line of Outback inverters.
CLEANING UP YOUR GREEN POWER
This is a Stetzer capacitive filter, composed of a small motor capacitor, a resistor to discharge the capacitor when it is unplugged, a couple of tabs to plug it in, and a plastic case. This one has been modified by wrapping an aluminum screen around it and securing it with "Zip-ties". This shields the home's occupants from high-frequency electric fields that radiate like an antenna from the capacitor's outer shell. I've contacted the manufacturer about this problem (including electric field readings before and after alteration) and received no response, but this rig works well.
But by contacting your inverter's manufacturer, the technical staff may be able to build a frequency-targeted filter specifically designed to remove the unwanted frequencies the unit generates. We have done this with a call to Exeltech for our XP1100 inverter. This is what they sent. We wired it into the inverter's output and enclosed it in a metal box to shield its fields. The Exeltech sees the capacitor in a Graham-Stetzer filter as a challenge to put the voltage and amperage back in synchronization. This makes for a very unhappy inverter. The solution from Exeltech is lots of induction and very little capacitance. This creates a large localized magnetic field, so the filter they sent was enclosed in a heavy steel box that blocks most of the field.
And this is the final stop for AC current moving from the inverter filter to the AC loads. As you can see, we have only two AC circuits in our breaker box. One goes out to our shed where it powers chargers for an electric mower, electric car, and a "string trimmer". It also powers an irrigation pump for the garden and an electric rotary tiller for the garden (Mantis brand). Plus it powers various AC shop tools and AC lights, when needed. And most recently it is being used to keep our electric car's gel-cell batteries warm on super cold (-22F or lower) winter nights.
LOAD MANAGEMENT - "NEGAWATTS"
Amory Lovins of the Rocky Mountain Institute coined the term "Negawatts" to describe power that you didn't have to generate because you lowered your power requirements. In our household we call this process "Load Management". It involves the standard conservation methods of turning off unused lights, finding and eliminating "phantom loads", switching to energy-saving lights and appliances, etc. But we also include behavioral changes based on the weather forecast and power system design to maximize overall system efficiency.
The changes in behavior are what give conservation a bad name among those who don't really know how much energy they need to use, who have never been without an unlimited supply, and who aren't interested in following Nature's rhythms. If we know that it's going to be quite cloudy for a week or more, we might delay doing the laundry, hold off temporarily on some big computer project, or watch a DVD on the evening of a sunnier day.
If you would like to figure out where the big power uses are in your household electrical system you can use a worksheet that we have prepared. It uses a conversion factor that takes the typical 87% efficiency of an inverter into account when estimating AC loads. Simply look for the nameplate on the device or appliance and you will see figures for volts, amps, or watts (volts times amps). Fill in the figures and you will see what your biggest consumers are. From there you can determine what needs replacement or possible elimination. Or you can buy/borrow (around here, from local public libraries) a recording kilowatt-hour meter (like the "Kill-A-Watt" from Intertek) and simply plug appliances into it for a period of time to see their average electrical consumption. This works really well for intermittent loads like refrigerators/freezers.
Power use that maximizes direct use of solar energy, as it is produced, is our first priority. Direct use eliminates battery storage losses, which range from as little as 1% to as much as 30%, depending on battery chemistry and age. Second priority is using DC lights and appliances, powered straight from the batteries. This avoids lost efficiency from inverter-supplied AC power, which normally exceeds 10%. And, very importantly, we keep the solar panels clean, unshaded, and at an optimum tilt angle to capture maximum solar input. The individual solar cells of a solar panel are wired in series to obtain sufficient voltage for charging a battery or powering an inverter. And the flow of current in the panel, or in an array of panels wired in series, is limited to the lowest cell output in the series. Shading even one cell with dirt, leaves, or snow can cut the current flow from the affected panel(s) dramatically. For more details, check out our book, "Peoples' Power Primer" on our Products & Services Page.
EMF (Electro Magnetic Fields) and "Stray Voltage" (returning neutral ground currents) are causes for concern in any home electrical system. Low voltages generate the smallest electrical fields. But high-powered, low-voltage appliances require a lot of amps, generating large magnetic fields. Electromagnetic fields are easily reduced using two simple wiring options. Closely twisted wires, each with an opposing direction of current flow, cancel each other's magnetic fields to a large extent. And enclosing wire in a spiraling steel ("Greenfield", "MC", or "BX") or solid steel conduit (EMT) that's grounded will shield you from the electric fields. But the best options are Distance and less Duration. Doubling your distance from household wiring gives you one-half to one-fourth the EMF exposure. And turning off an inverter eliminates the time spent soaking up higher-voltage electrical fields from AC wiring and from high-frequency "radio" waves generated by the inverter itself.
RECENT UPDATES (July 2012)
To find out about the most recent updates to our 2012 electrical system you can read more on our blog site.
Essentially, we added three more 135-watt Kyocera PV panels to have
more charging capacity for the electric car and electric tractor,
without using power from the panels that power the house. This involved
buying a second Outback Flex-Max charge controller (an FM-60, to handle
the output of the three new panels plus 3 older Kyocera KC-120s), along
with some added wiring, an inexpensive galvanized pipe PV rack, and some
added electrical breakers and boxes. I'll add more details including
photos as soon as possible. The bottom line: now we can drive to Winona
electrically (26 mile round-trip) and recharge the car in just two sunny
days. And the tractor charges much more quickly after mowing the
orchard or walking trails.
SOME HELPFUL WEB RESOURCES:
- The Midwest Renewable Energy Association - The_MREA.org
- Home Power Magazine - HomePower.com
- Solar system details with loads of good graphics
- NABCEP Installer's Guide for those who really want to get it right the first time
- Our electrical consumption worksheet will help you to find where your power goes
- Sun Electronics solar system size calculator (you may also need a figure from the next item to make it work)
- U.S. Solar Radiation Resources Maps, by month or annual, using various collector tilts/tracking. Just check four choices and you get a map showing, essentially, how many hours of full, 1000 watt/meter, hours you will see at your chosen panel angle, for a month or year, either as an average, minimum, or maximum.
- SolarDesignTool.com's PV comparison page, listing most of the current commercially available PV panels by brand and model number.
- U.S. map of Annual Cloudy Days per year, to help estimate PV system sizes
- Our logical flow chart showing how we plan a renewable energy system
- An excellent article from Homepower Magazine about how to choose a wind-turbine
- Homepower Magazine's 2011 buyer's guide to wind-turbine models
- Homepower Magazine's buyer's guide to hydro-electric turbines
- U.S. average wind speed map at 262 feet above terrain
- U.S. average wind speed map at 33 to 164 feet above terrain
If you have any questions about EMF, how we've dealt with it in our home, or you'd like help figuring out what to do about your own electrical/geopathic energy situation, check our contact details on the Home Page , click here, click the button at the left, or e-mail our Secure GMail.com account listed as "bobdowser".