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Where to buy a solar generator and what size do I need.

Marty4321

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We are a small community garden with no electricity. We already have a system to pump water up to a tower but the watering is gravity fed. We are looking into getting a grant to expand our system to use a sprinkler system and I need to get a price quote for a solar powered generator.

(1) I need to run a 12VDC / 17Amp irrigation pump for one hour before dawn six days a week. I would like to buy a solar-powered generator to do this. I could also do this with a 120vac 300-watt system.

(2) Also, I need a 120 VAC / 300-watt existing pump for 30 minutes (as opposed to one hour above) with no sun. It must switch OFF when the sun is available.

I am going to put in a quote for the grant for both systems so I need to find a company that can supply (1) a generator for the first one; (2) a generator for the second one, (3) a generator powerful enough to do the two together. I know this could be designed and built but to go into a quote for a grant it is best to have a quote from a reputable company.
 
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Welcome to the forums Marty!

Not a hardware guy so no recommendation from me other than to check out Will's video's and DIY Solar Blueprints. Anyone handy enough to change a car battery can build what they need for about half the price.

Example Math
First step is how much power do you need? watts hours = volts x amps x time = 12 x 17 x 1 = 204 watt hours.
The other system consumes 300 watts for 30 min or 150 watt hours, but, it's AC so will have an inverter efficiency loss. Assuming 85% efficiency than that's 150 / .85 = 177 watt hours.

Your combined energy storage needs are 204 + 177 = 381 watt hours

Lead acid should have a max DoD of 50% and an 80% round trip efficiency, so 381 / .8 / .5 = 952 watt hours, or at 12V = 80 amp hours.
Lithium should have a max DoD of 90% and a 90% round trip efficiency, so 381 / .9 / .9 = 470 watt hours, or at 12V = 40 amp hours.

From your other post we know you live in Tampa, so you probably don't have to worry about cold effects, but the battery FAQ can explain a lot of that to you if interested.

Hopefully that'll let you figure out how to slice/dice any changes that come up and give you something to keep your "professional quote" honest.

You didn't ask about how many solar panels you'd need to recharge the battery, but if you want to know that just divide the consumed watt hours by the lowest insolation for the given month the system would operate in. For example, 381 / 3.5 = 109 Watts of solar panels. One 100 watt panel would probably work to keep the system charged except for January.

From the math above, looks like a solar generator above 500 watt hours would work. The inverter should also be able to provide the AC load of 300 watts plus whatever it's inrush current is (as this is an AC pump, it could be very substantial, e.g., 3000W, you'd need a clamp meter with in-rush to know for sure... possibly a soft-start device might help there).

Hope that helps! Please post photos of your gardens!
 
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We are a small community garden with no electricity. We already have a system to pump water up to a tower but the watering is gravity fed. We are looking into getting a grant to expand our system to use a sprinkler system and I need to get a price quote for a solar powered generator.

(1) I need to run a 12VDC / 17Amp irrigation pump for one hour before dawn six days a week. I would like to buy a solar-powered generator to do this. I could also do this with a 120vac 300-watt system.

(2) Also, I need a 120 VAC / 300-watt existing pump for 30 minutes (as opposed to one hour above) with no sun. It must switch OFF when the sun is available.

I am going to put in a quote for the grant for both systems so I need to find a company that can supply (1) a generator for the first one; (2) a generator for the second one, (3) a generator powerful enough to do the two together. I know this could be designed and built but to go into a quote for a grant it is best to have a quote from a reputable company.
Hi Marty, I don't know if you have identified the solution you want yet but if you are still looking I would like to try and help.
My first experience in solar was a water pumping system in Nigeria in 2011 and since that time I have moved and live in South Florida and this type of need is what I like to help with. I am operating a solar energy company that deals with portable and off grid or emergency power requirements. As another person posted the batteries you choose to work with are important but equally important is where they are located and protected from the environment. Here in Florida the heat is a major concern as batteries want the same environment as people, not too hot, not too cold. Your design must accomodate some type of environmental protection from the elements. Contact me directly if you would like more information. - Barry
 
I emailed you back directly (I think). I am not sure if I did it correctly. Did you get it? Marty
 
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