Posted: 1/15/2012 10:41:07 PM EDT
Good Evening all, it’s been some time since I have visited ar15.com  but it’s good to get back on and read what you all have going.
So here’s my project I have ahead of me, I just purchased 80 acres no water no power and nobody for about 15 miles or so. I plan to drill a well this spring but in the mean time I am going to move a small camping trailer out there and I have been looking into solar kits to run some lights outside and to maintain the trailer and would also like to even run the well pump solar once its drilled. Can any of you point me in the direction as to a good kit or give me some pointers on how many watts I may need to meet this demand. I’m no electrician so any help or suggestions will be much appreciated Thanks GUNSAP |
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You need to add up the loads first.
I could guess how big your water pump is or if you're going to run two 15 watt lights or five 300 watt ones but then the math is only a bad as my guessing. The other thing you need to figure is how long the sun shines on an average day (references for this are on line) and how long you're going to drive the load. If the sun shines 6 solar hours a day and you're going to run the load 12 hours a day that means your array is going to have to be twice the size of the load's requirements (and then some more for padding). |
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Quoted:
You need to add up the loads first. I could guess how big your water pump is or if you're going to run two 15 watt lights or five 300 watt ones but then the math is only a bad as my guessing. The other thing you need to figure is how long the sun shines on an average day (references for this are on line) and how long you're going to drive the load. If the sun shines 6 solar hours a day and you're going to run the load 12 hours a day that means your array is going to have to be twice the size of the load's requirements (and then some more for padding). Ok so where my land is located the average is 6 solar hours a day. I’m not sure how deep the well will be so I am figuring .06kw and about 100w in outside lights and not sure about the camp trailer. Does anyone know a ball park of what will be needed to run this or am I better off getting a large Generator? Thanks |
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I've stayed in several off grid cabins in NE New Mexico (mountains + Cold + Snow). The best combination I have seen includes Solar/batteries/inverter plus a Gen set. IIRC, they had about 400 - 500 watts of solar panels, eight 90 amp/hr batteries. Gen set was small...maybe 8 kW propane. Battery charger, build into the gen set, was rated about 200 amps or so. (onan portable welder type gen set that provided high amp dc output and 120/240 ac)
Indoor lights primarily 12 v LED, Outdoor porch light 12v LED . 12V RV TV/radio. Forced air fans in the fireplace and ceiling fan = 12V. Propane/12V dual power frig. Cell phone charger, laptop charger, and a few other odds and ends all 12 v. The plan here was for all the ROUTINE, small loads, to run without an inverter (Inverters waste power anytime they are on, but not driving anything. They also have conversions losses. The best are around 90% efficient) Florescent outdoor flood lights, DSL modem, cd player, printer, bigger indoor florescent lights, and the like were powered by a couple of small, very efficient inverters (200 Watts?) that only ran when you needed it. Microwave, kitchen appliances, vacuum cleaner, etc were powered by a big hoss inverter (2000 Watts) On demand propane water heater, with battery ignition system. Standard 240 volt submersible water well pump, but a BIG ASS PRESSURE TANK. The pressure switch on the tank was wired in parallel with the start run circuit on the generator, along with a low voltage relay from the batteries. When water pressure got to about 20 psig, the gen set cranked and the well ran. When the tank reach max pressure, the generator shut down, unless the battery charger needed juice (the well pump had the standard pressure switch to control it when the gen set needed to run for the battery charger.) With four of us in the cabin, taking conservative showers, the pressure tank was large enough the the gen set would crank only once or twice a day to refill the pressure tank. This took about 15 min run time. Batteries also got charged during the time the well was running, so the gen set, when it did run, was pretty much always at full power/efficiency. If the solar panels did not keep up with daily demand, because usage was high enough, or the weather was bad, the gen set would crank to charge the batteries. When it cranked for this, it took about 1 hr - 2 hrs to bring the batteries back up to charge. This cabin was rented as a mountain get-away...so it was intended to maintain a certain level of creature comforts, all many miles from the nearest power lines. (Don't ask about the dsl part...there is some strange law in NM that makes the phone company run DSL to any house for only an hundred bucks...no matter how far it is). At the same time, it gave you the distinct feeling you were living better...with less impact on the environment. The kids really got into the 'saving power' bit and watched the little lcd battery display every time they turned something on. Spousal unit and I never felt we were doing without The owner said it averaged about 1 gal/day of propane in the summer months and about 4 gal/day in the winter months, if the guest heated with wood. She also said the combination of solar/generator was much more cost effective than a complete solar system. My memory is not great, but I believe she said the solar system was under $3K and the generator another $2K. She was talking about 5X that to have a completely solar system that could run the water well and provide reasonable assurance that her customers would not be in the dark too often. Although my current weekend cabin has utility power and 'city water', I like this model. My two year plan is to drill a water well this year, then put in solar next year, to allow us to live without utility power in the long term. I also plan on instaling a well pump that is designed for lower current, longer run time. This makes it cheaper to size the solar to run the water well, if it has to. |