Darrin's Alternative Energy Page
As I mentioned on our House page, our local utility just couldn't seem to get it together. Power was horrible from 1989 to about 1996. We designed this system during that time and it has performed flawlessly for us since then. Basically, it can be thought of as a "whole-house Uninterruptible Power Supply" which transfers the house onto battery power during brownouts and blockouts. Here's a view of it...
We do also have grid power available here at the house. I ran the cable underground myself to the nearest utility pole - about 5600' away. I used pad-mounted 50KVA 30:1 transformers at each end. They step the voltage up from 240VAC (which the utility supplies and meters) to 7200VAC. I am using a concentric-neutral cable buried at 36". At that time, I also ran my own six-pair phone line in the same ditch at 12" below ground, but a solid 2 feet above the power cable.
The heart of the system is the Trace SW-4024 24VDC 4000W continuous (12,000W peak) sine-wave power inverter...
It monitors the state of our incoming utility power. In the event of a brownout or blackout, it transfers our whole home over to battery power in mere milliseconds. The personal computers don't even flicker when the transfer takes place. The SW4024 is bi-directional and functions as an inverter (making 120VAC from 24VDC) and as a battery charger when the need arises. This inverter is wired through an Ananda Power Technologies 400 amp DC power center to a bank of IBE 85N-33 industrial fork-lift cells. The battery pictured below weighs 3,700 lbs...
This battery is good 1673 amp-hours at the 200 hour rate. (Over 2000 AHr at the 100 hour rate.) In our home, we can get about four days of total autonomy (NO charging sources whatsoever) from this bank, when fully charged. Our biggest loads are our standard-efficiency food storage appliances. The refrigerator and chest freezer are both typical ~2KWHr/day consumers. They do NOT do well in an alternative energy application. To be pure, we should have used a super-efficient DC freezer and DC or LPG refrigerator. (No problem, though, the house is wired and plumbed for those appliances should we ever decide we need them.) Our grid power is seldom down for an extended length of time, and we rarely go 48 hours without wind or sun, so we've never had a problem. There's even a back-up gasoline generator if needed. So far, we've never had to use it. It's a real treat during the winter to lose power now! The snow, wind, and cold are locked outside while we're warm and cozy inside watching a DVD movie or learning a new application for the PC. (No, I can't weld when we're on alternative energy, but that's life!)
None of the above components makes this an Alternative Energy (AE) system. The solar panels and wind charger put us in that category. Our main AE collection component is an array of 16 85W Solavolt 8500 36-cell photovoltaic panels... In full summer sunlight, I've seen 44 amps at 26.8 volts from these. Over a kilowatt!
If it's cloudy and stormy, then the wind is usually blowing, so we also installed a Whisper 1000 wind charger on the side of my home-brew MIG-welded amateur radio tower...
This wind charger will make a little OVER a kilowatt when the wind reaches 27 mph. It can really help when the batteries are low. We usually keep the electric brake ON (basically shorting the wind charger output) to save the bearings and other moving parts.
The house was wired with the system in mind, so we have lots of breakers, redundant circuits into many rooms, and over 7500' of Romex in this project. It took me roughly three months to wire this house by myself. The reason we have redundant circuits is to prevent some outlets in certain rooms from tapping into battery power.. For example, we didn't want to be able to use the electric grill portion of the gas cook top active if we lost grid power. Heat from electricity is MOST wasteful.