OFFGRID SOLAR POWER SYSTEMS

Note: Anyone considering offgrid solar systems, check into at least a 24v-48v system. We are already realizing that this is not enough. Some of the advantages are using smaller wire over longer distance.

I don't care how much you read. You will probably do something you wish later you had done something else. The important thing is that you did it.

We went into the solar aspect of our home thinking none of it would be a waste. If we made a huge mistake calculating our energy needs, we could eventually put it out in the workshop and start new with what we really needed.

The power tool batteries will fry on modified sine wave. If the apparatus that you want to charge has a cube (transformer), you can use the modified sine wave inverter, if it does not it will mess it up for good. We melted a charger for power tools and a digital clock that ran continuously faster.

The batteries are connected in parallel similar to this schematic of a small solar array. We have a 60 amp charge controller with a digital read out. We will be able to hook up our 7500w gas generator to the 2400w inverter and charge our batteries when we do laundry and during monsoon season.

The recommended distance from the inverter to the off grid batteries is only 5 ft. Wire size is directly related to the distance.

We temporarily mounted the 1200w modified sine inverters and a 300w pure sine inverter for our offgrid solar needs. The pure sine wave inverter is for the computer and to charge the power tool batteries. Right now the inverters are mounted inside the house.

We should have gotten a larger pure sine wave inverter for our offgrid solar system. Our ceiling fans have a loud buzzing when we turn them on using the modified sine. Makes it very difficult to sleep at night. Since the ceiling fans are our only means of cooling other than the wind, it has become a pain. We did manage to find ceiling fans that only use 8 watts on low which is tremendous. We looked into 12 volt ceiling fans and weighed the extra cost against the gain in solar. We decided that we would put our money into solar so that it could be used where and when it was needed.



This is our new Xantrex 2400 watt DR series inverter/charger. It is our newest offgrid solar device. We will be able to plug into the gas generator to do laundry and charge our batteries at the same time. This inverter shuts down at 11.8 amps under no load enabled and 8.5 amps disabled. These numbers do decrease under a load. It senses keeping an 80% charge on the battery bank. Every inverter is different. We think we are going to keep the 1200 watt inverter for the lights and put everything else on the Xantrex. The ground bar (the small bar above the inverter) bonds all service equipment and metal enclosures to earth ground. One wire was used to bond each enclosure instead of loop between.

Update August 14, 2007-During this monsoon season we have been struck by lightening twice, but did not get a direct hit. We believe it is coming up from the ground through the lightening rod.

One of our neighbors took a direct hit and it blew out his inverter and at the same time our inverter was hit. We had to wait for the inverter to cool down and Ron reset it and it came back up.

The second time a different neighbor took a direct hit to their wind generator and melted one of the blades and fried their generator. Our neighbor to the east called me because she saw the lightening hit over our house, but again it shut everything down and after cooling off for about 15 minutes I was able to restart the inverter.

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The deep-cycle batteries are housed on the east side of the house. They need to be insulated and vented to the outside. We just built a battery bank and inverter room.

I received several emails regarding the dirt on the batteries. Here you go, clean batteries. The white stuff around them is snake a way. The snakes don't seem to mind the batteries being dirty.

The batteries are rated 115 amp hours over a 24 hour period. We should have had a battery back up for 4-5 days. Again, my understanding was incorrect. In theory, this would have been correct.

The problem is, I did not understand that our 1200w inverter shuts down at 10.5 amps. So, we only have 4600 watts of usable battery storage. We have about 2 days conservatively. We also did not use our propane refrigerator as intended when I did our calculations for energy needs.

Update March 2, 2008-We bought a small electric refrigerator 1.5 amps which uses most of our energy, about 1500 watts a day. It cycles every 15 minutes for 7 minute intervals.

When you calculate your energy usage for your offgrid solar system be sure you know the appliances that you intend to use. If you change your usage, you also need to add more solar or adjust somewhere else.

For more information regarding offgrid solar battery storage please, look at these battery calculations by Xantrex. All of the batteries were made within 3 months of each other. We chose these because they are easier to handle than the L-16s.

Solar Hot Water Bible: Do-It-Yourselfers & Contractors - Learn from the solar water heaters industry leader

For more offgrid solar information check out Total Solar Energy

Please consider Solar energy advantages & disadvantages before making your offgrid solar choices.

OFF GRID WIND GENERATOR

It has a built in voltage regulator. It has a brake and is rated for 400w @ 27 mph with a start up of 7 mph. The average wind speed here is 12 mph.

The windmill is attached to the house for a supplemental off grid energy source. We used schedule 40 for the pole. The noise inside the house is minimal. It is a very light whirling sound that is barely noticable unless it is totally quite in the house. I am a little disappointed with my understanding of the curve when the wind is not at maximum. The watts seriously drop to about 25w @ 12 mph. I am still happy (living off grid) that we have some alternative power during monsoon season.

Before we left the city, we started checking our water and electric bills to see how much we used.

Compared to what we use now it was ridiculous. We cut our water down to what we knew it should be about 40-50 gals. per person per day.

Our electric was another story. We used about 24,000 watts of electricity per day after we bought all of the energy saving light bulbs and changed what we could. We probably had 8-10 digital clocks running all of the time. The stove, vcr, alarm clocks, stereo, dvd player, instant on TVs, microwave, washing machine, dryer most appliances are always on.

We currently use about 2500 watts per day. This is about 1/10th of our use in the city. Other than a few minor things, there is nothing we miss. We did a calculation sheet similar to this calculation sheet.

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