Cutter and I lived off the grid using a generator and batteries from December 1999 through the middle of May 2000. For almost 6 months the generator and batteries were our only source of power. The following is an account of:
Our Power Generation System We used the attached Watt Usage Chart to determine how many watts we needed to run everything in our 2000 square foot doublewide. We have an electric water heater, electric dryer, 70 amp battery charger, 4 ton air conditioner, and a well with a 1 horse power motor. These items are the biggest users of electricity at our home. These items alone use 12,700 watts.
If you take all our other electrical items (2 refrigerators, 1 freezer, coffee maker, microwave, TV, VCR, lights, central air system [for heating and cooling], ceiling fans, radio) we can run all of them together and they do not exceed 5000 watts.
If we had everything running at the same time we would be using approximately 18,000 watts. However, since we knew that we would not be using the air conditioner in the winter (3,000 watts) we knew that 15,000 watts was our maximum. Even then, we would rarely be running everything at the same time.
After figuring out our watt usage we decided to use a 15KW diesel generator (attached is a sheet comparing Gasoline, Propane, and Diesel Powered Generators - hands down the Diesel is the most cost effective and reliable). We also got a 5,000 watt 120-volt inverter from Sportsman's Guide. To power the inverter we got seventeen 200-amp deep cycle batteries from Carquest (these have a 5-year warranty).
We purchased (30) 55-gallon plastic drums from a local drum recovery company and filled them up with off-road diesel back when the prices were in the 70-cent range. This gave us approximately 495 days of running the generator at 10 hours a day. We covered the drums with a tarp and used a hand pump to transfer the fuel from the drums to the generator.
How We Hooked It All Up For legal and safety purposes we used a 200-amp Transfer Switch. This is a box that we mounted outside our back door. It has 3 sets of connections inside of it. The middle connection runs to the fuse box in the house. The bottom connection ran to the generator, and the top connection ran to the inverter.
When the lever is pushed down it feeds electricity from the generator to the house, when the lever is pushed up it feeds electricity from the inverter to the house.
The installation of a transfer switch should be done by a licensed electrician. If a fire were to occur and the insurance company was able to show it was due to faulty wiring they would not pay if you did it yourself. Neither of us is licensed, and I am not giving any type of instruction on wiring (read, "legal disclaimer"). It was very easy for us to do the wiring ourselves using a voltmeter and much caution. The charts at the hardware store where we purchased the wire showed what gauge wire to use for the 15,000 watts we would be using based on the length of the wire etc.
We set the generator about 10 yards to the side of the home and ran the wire from it to the transfer switch. We used a plug at the generator so that we could unplug it if we had to move the generator. The generator was mounted on a small trailer for easy moving.
We did not enclose the generator at all and when the doors and windows were closed in the house you could not hear the generator.
We set the batteries in a row under the house, hooking them up in a series + to + and - to- along the row. From the end battery we ran wire up through the floor of the house to the inverter. Then ran another set of wires from the inverter out to the transfer switch. This was all hard wired.
Also under the house was the battery charger.
What Worked And What Didn't During the day we would run the generator and it powered the house and the battery charger with no problems. We would run the generator between 8-12 hours a day and then run off the batteries the balance of the time.
When running off of the batteries we experienced a few things:
We do not have a large enough battery charger. We started out with 12 batteries and that would not get us through the night. So we added 5 more batteries. We would use between 600 and 1500 amps a night. (you never want to drain the batteries below 50% charge, so 17 batteries at 200 amps each gives you effectively 1700 amps to work with when they are fully charged)
Since our battery charger is only 70 amps that means in 10 hours of running the generator we are only charging the batteries 700 amps. We would then have to run the generator longer some days than needed only for the purpose of charging the batteries. Usually once a week we would run the generator for a 24-hour period to make sure that the batteries were fully charged. This was a waste of fuel and we will be getting a larger battery charger before next fall.
When running off of the batteries our electric clocks did not keep accurate time. Also, we could not charge any Nicad batteries while running off the batteries.
Since the inverter only provided 120 volts we could not run the well off of the batteries. Most nights this was not a problem (the 50 gallon pressure tank that is part of the well system gave us enough) however, there were times that we left the hose on and had to start the generator just to get some water.
The day before the electric company installed the line to our house to put us "on the grid" our inverter made a popping noise and started smoking. We turned it off and packed it back up and sent it back for a refund (it was still under warranty).
In the 5+ months that we ran the system we never had to add any water to the batteries.
The generator required oil changes every 100 hours; however, we used an oil additive (Petron) and felt comfortable going 130-170 hours between changes.
We did check the oil level and coolant level every day. Never had to add any coolant, however, the nature of a diesel is to use a little engine oil and we usually had to add a little every day between oil changes.
The fuel we have is pretty clean and we could go about 2 months between changing fuel filters.
As with any diesel we used a fuel additive that prevented gelling, dispersed the water, and increased the cetane level.
We did not enclose the generator at all, so when it rained we made sure that the generator portion was covered. We used a tarp, making sure not to block any vents. When the engine was not running we covered the exhaust pipe.
In the morning Cutter would usually be the one to start the generator. It is important to let it run about 2-5 minutes before putting a load on it. In the evening I would flip the switch over to batteries and then let the generator run about 2 minutes without a load on it before shutting it off.
What We Would Do Differently Get a larger battery charger. This was poor planning on our part. We could comfortably run the generator only 8 hours a day, sometime less, but had to run it longer just to get the batteries charged.
Future Plans There are 3 reasons that we went on the grid.
We wanted air conditioning for the summer and though the generator can easily pull the air, we only have a 120-volt inverter and the air is 240 volts. It is not less expensive to run the generator 24/7.
We are hoping that fuel prices will drop and wanted to save the fuel we have for a time when we may not have an alternative.
When outside of the house on the side that the generator was it was loud enough to be irritating after the first 3-4 months. We live out in the woods and I enjoy the peace and quiet of the woods.
What I am looking at getting done in the next couple of months is the following:
Building an enclosure for the generator, not so much for weather as for noise suppression.
Getting a 240-volt inverter and a larger bank of batteries along with a much larger battery charger.
When the weather starts cooling down we will go back off the grid. Maybe before, depending on getting an inverter big enough to power the air conditioner.
Generator cost of $6000 divided by useful life = $1.50 a day (running 10 hours a day)
Battery cost of $60 x 17 = $1,020 divided by useful life = 56 cents a day
Inverter cost of $650 divided by useful life (?) = 35 cents a day
Fuel cost = 2.33 a day (running 10 hours a day at 70 cents per gallon)
Maintenance cost = 40 cents a day
This adds up to $155 a month for unlimited power 10 hours a day and sufficient power the other 14 hours a day. Depending on where you live and how many in your household this may or may not represent a savings. It does give an idea on how much it would cost to live off the grid.
(If your electric needs are not as great you can get by with a smaller generator reducing your daily generator cost from $1.50 to as low as 60 cents.)
NOTE: We could live much more frugally, thus cutting quite a bit of the daily expense in running off the grid. These are the cost we incurred living pretty much as if we were still on the grid.
Another item to note: we use a wood burning stove to heat the home during the winter, however, there were times that we turned on the natural gas heater and the generator or batteries powered it fine.