I'm going to go back to 2001-2002, some 7 or 8 years ago and recount my first attempt at living off grid. I live in Northwest Iowa, which is a prime location for wind power, as anyone who lives here can tell you! So my thought process was to go primarily with wind power, using solar as my secondary source of electric power. I felt with a large enough battery pack, I could go between windless days with solar power supplementing the wind.
Here's my first series of homemade wind generators with my pooch Cosmo inspecting it.
These first wind machines used surplus 90 volt, 1,200 rpm permanent magnet DC motors as a generator. Notice I had the tower stub offset and used a hinged tail with a spring to "furl" the machine out of high winds. These machines used a 6' diameter blade set and really did produce nice power. 2 problems with the design: I probably should have used a lighter spring to furl it out of the wind sooner, but the second problem was probably inevitable anyway. The bearings in the motor simply could not handle the load. The bearings usually failed after only a few weeks of use, resulting in blade damage as well.
Later, I moved to a homemade alternator in a totally scratch built wind generator. This unit featured 8' blades and provided much more power. At the same time I was using several homemade solar panels as well as a couple of thin film commercial 20 watt panels.
Here I'm installing the thin film panels.
The homemade solar panels were a complete bust. I can't imagine how many hours I spent soldering cells together. 3 panels I made from broken solar cells, 2 were made from new 3" round cells. The broken cell panels never did give me more than 1 amp each, the commercial cells did better, but all told the 2 thin film panels, 3 broken cell panels and 2 new cell panels only gave me a charging current at the batteries of less than 6 amps...
I purchased a Trimetric battery monitor system, and carefully logged data every day from April through November of 2001.
Here's a blurry shot of the Trimetric showing 14.8 amps going into the battery bank.
Here's my bank of 12) 6 volt golf cart batteries. Notice the shunt for the Trimetric on the wall above the batteries. Note also the massive copper wires used to hook up the 5000 watt inverter (which isn't hooked up at the moment).
Here's my last generation wind generator ready to be installed the summer of 2001.
I made a movable crane, well ok, it's just a 2x6 with brackets that catch in the tower. But this device allowed me to raise the tower sections one at a time, in the picture it's raised up now to allow the generator to be hoisted on top of the tower.
I used a couple of pulleys and the lawn mower to pull up the generator.
Here I'm strapped into a safety harness and attaching the generator to the tower head.
Here's the generator up and running.
Prior to this last homemade generator, I had an Air 403 commercial generator up for several months. I had the Trimetric connected to the output of the Air 403, recording exactly how much energy it produced. I also had a weather station on site, so I could record wind speed data. In a nut shell, the Air 403 was the worst wind generator of them all, while it was dependable, it made so little power it wasn't worth being on the tower. I sold the Air 403 and used the money to build the above generator.
This new generator was great, while it was working I never once had to charge my batteries with the gas generator. It put out 10 to 15 amps in a mild breeze, and on windy days it would put out over 100 amps. I saw a peak of some 130 amps in a major wind event. But alas, I didn't have a tail furling system on it. I had hoped it was robust enough not to need it. But one late fall day in 2001 we had sustained winds of 40+ mph all day long. The stator overheated and burned out 1 of the 2 phases. When I noticed the lower power output, I went outside to see what was up. Much to my dismay and amazement, the generator was throwing huge sparks with smoke billowing out. The unit continued to work after that, but only at about 1/2 power.
During the late winter of 2002 I severely cut my index and middle fingers on my generator engine fan blade. The right hand was useless for weeks. Shortly after my hand healed to the point I could use it again, I tore a muscle in my back. I was down, unable to do anything for almost 2 weeks. I needed to be up and about to run my generator, pull starting it no less, I couldn't do it. So I had the utility turn the power back on. It's been back on since March 2002...
So what exactly went wrong, and what went right?
I knew I had to reduce my overall power consumption, my range was electric so I purchased a no electric gas range at Sears. I replaced my electric water heater with a gas water heater. Lastly I replaced my big refrigerator with a small, energy efficient new unit and sold my chest freezer to a friend. I used a ventless propane room heater for heat (which I already had) and didn't use my 240 volt electric base heaters. I was thinking I could get by on about 3 kWh hours a day...
I purchased a 5000 watt continuous inverter to power my house. The problem with inverters is they are on all the time, and consume a fairly large amount of power even under no load. The new refrigerator still used about 1 kWh of power daily. All my lights were still 120 volt lights, pretty much all were either fluorescent or compact fluorescent, which was ok, but they still had to go through the inverter which at best is about 85% efficient. TV at 125 watts, computer at 250 watts, it all uses power...
My 3 kWh daily use wasn't too far off though. The problem was the wind power, I was expecting too much from it, and my designs proved unreliable. I really needed three things changed. 1) I needed to reduce my consumption. 2) I needed more solar power. 3) I needed a more reliable wind generator.
Fast forward to 2007. I decided I had been on grid power long enough, it was time to come up with a strategy for a new power system. This time I'd take it slow, not jump in too quickly and plan better. I decided I'd move as much as I could to 12 volt power, this not only reduces the inverter load, but it's more efficient and reliable. I purchased a set of 3) 15 watt solar panels from Harbor Freight. Each panel puts out around .8 amps into the charging system. I also purchased a 15 amp Siemans charge controller, then added a second set of 3) 15 watt panels and a 12 volt deep cycle battery. At this point I was making enough power to easily meet my home lighting requirements. So I went about rewiring fixtures and ceiling lights to 12 volts. I added 12 volt outlets to several rooms for plugging in 12 volt lamps, fans, chargers, etc.
Spring of 2008 I added a third set of the 15 watt panels. Now I was lighting my home from solar, charging my cell phone and camcorder batteries, running my laptop computer all off solar. But I wasn't using a fraction of the power I was making, even in the middle of winter, my batteries would fill before noon. I started wondering what my energy requirements would be, and how I could cut them even more. I looked at 12 volt refrigerators, I see a chest type 12 volt fridge is now sold that only uses about 232 Wh a day. Sweet! But, it's $1,200, and I'm not ready to spend that kind of money just yet. What I do have is an older 5th wheel camper with a propane fridge/freezer in it. So I could use that for a while, cutting a third of my power useage right there. Yes, I'd still have to use propane, but it would make for a nice stop gap measure until I could increase my solar array. The next biggest load would be my TV, yes, I do run it a lot more than I should... So I looked at the new LCD TV's, much to my surprise, they were fairly power hugery. There was one 32" HDTV that only used 80 some watts, but it wasn't highly reviewed. What looked like the best deal for power saving was a 19" HD set that only used 32 watts. Add an invertor to power it, and you're still only looking at about 40 watts per hour. Now that's something I can live with. The small TV can also be used as a PC monitor, which I really need anyway.
So there I've got my basics. A propane fridge/freezer, solar water heater, propane stove, laptop on 12 volts, home lighting and a TV; and I'm making almost enough solar power for all that now. But there are other things, washing machine, vacuum and shop tools to consider. While they are high drain devices, they aren't used often. So I could run my gas generator once or twice a week for an hour or two to power those devices.
One other scary aspect of going off grid is air conditoning. My first attempt off grid, I ran the generator a lot in the summer to power the air. The real problem is that the west side of my house gets very hot in the afternoons as the sun just beats down on it. That's also where most of my windows are. If I close up my house in the mornings, it really stays quite cool unitl late in the afternoon. I think the answer is an awning, or sort of porch on the west side to keep the sun off the building. That's a project I've had on my list of "to do" things for a couple of years. When I go off grid this time, it's going to be a requirement...