solar panel to power 12v battery&pump

[trauts14]

can somebody suggest a solar panel to charge a car battery. i want to use a car battery to power my 12v water pump which will water my garden one hour a day. my 12v timer will regulate the time the pump operates.

i just need suggestions as to what panel will be good. i do have the ability to charge this car battery once a week. i do not think the pump will draw a huge amount of juice if only powered one hour per day. i just want a small panel to charge the battery so maybe i do not have to charge it with my battery charger.

my plan is:

solar panel--->solar charge controller---->12v battery-----12v timer---->12v water pump------->soaker house for the garden

[Sunking]

Well first you should not use a car or starting battery, they are not made to do what you want. You want to use a deep cycle battery.

All anyone can do is guess what size you need because you have not given any details. We need to know what size the pump is in electrical power called watts or horse power, and your location. If your pump is small say like 100 watts and you only run it 1 hour per day means you use 100 watts x 1 hour = 100 watt hours. A small solar panel of about 30 to 50 watts would work. If the pump is 500 watts ran 1 hour = 500 watts and you would need a 300 to 500 watt solar panel depending on your location and what time of year you will be running it.

So your guess is as good as anyone else. All I can tell you is a guess will be wrong, need data.

[trauts14]

Sunking, Thank you for your assistance. This is the pump i am currentlt using:

http://www.amazon.com/Jabsco-31700-0092-Washdown-4-3-GPM-12-Volt/dp/B000O8D5N2/ref=pd_sim_sg_3

i hook the pump to my car batttery, but i would like to just install a solar panel to recharge a "deep cycle" as you suggested. i use the pump approx one hour per day, and i do have a battery charger i can use. i was hoping a solar panel would eliminate the need for me to hook the deep cycle batt up to a charger.

[Mike90250]

12v 15 A, that's some pump. Not going to be easy to power that for 1 hour a day.
15 amps for 1 hour, is ..... 15Ah. So a "generic" deep cycle battery of at least 60ah should work. common size is 80ah & 100ah.
Also is 180wh So depending on your sun availability in your watering season, I'll guess at 4 hours. Because of battery recharge losses, and other inefficiencies, I think a 100W panel, charge controller, and fuse should round out the system.

[Sunking]

12v 15 A, that's some pump. Not going to be easy to power that for 1 hour a day.
15 amps for 1 hour, is ..... 15Ah. So a "generic" deep cycle battery of at least 60ah should work. common size is 80ah & 100ah.
Also is 180wh So depending on your sun availability in your watering season, I'll guess at 4 hours. Because of battery recharge losses, and other inefficiencies, I think a 100W panel, charge controller, and fuse should round out the system.

I concur with the caveat of your location and time of year you would operate would be more accurate.

[russ]

Right - For our newbies - remember that there is a rather great difference between LA and Seattle or New York for the amount of sunlight available.

In solar - not all places are created equal.

[trauts14]

i live in central NC. I need to do my research on solar/ sun supply for this area. i will serch the forums.

if i cut my pump use from one hour to 30 minutes daily will that (in theory) cut Ah in half and then i could get away with a 50 watt panel instead of 100?

[MarineLiner]

if i cut my pump use from one hour to 30 minutes daily will that (in theory) cut Ah in half and then i could get away with a 50 watt panel instead of 100?

[trauts14]

the garden is in an open meadow with great sunshine all day long. i do have a car batery recharger i can use if needed. i think 30 minutes a day would work fine. i would love to find a way to make it work without spending an arm and a leg.

[MarineLiner]

What is the source of water you pump from?
How deep is the suction ?
How high the head of water it should deliver ?
Could you store the water to use later ?
Those are needed to calculate the pump. Then we arrange the system.

[trauts14]

@MarineLiner
the pump i currently use is 12v 15 A
there is an incline and this is one reason i chose a strong pump, to defeat gravity's pull.

I cannot store the water. I pull from a creek with a depth of 8 inches. the pump works great when connected to a car. i want a solar panel to charge a deep cycle battery so i dont have to use battery charger every few days.

[MarineLiner]

[trauts14]

would a 15w solar panel be a waste of time if i used the pump (15A, 12v) 30 minutes a day?
since price is a concern, maybe i would be better off setting a 12v timer to run 2 days a week for 30 minutes, and then when i return to the house (im there during wknd) i can use battery charger on the deep cycle.

it seems if a small panel will only provide a small charge, then maybe im better off just hooking battery to a charger every few days.

any input is greatly appreciated

[Sunking]

it seems if a small panel will only provide a small charge, then maybe im better off just hooking battery to a charger every few days.

You are catching on my friend. The problem with any solar battery application is the electricity will cost you at least 10 times more than buying from commercial power for the rest of your life.. It is for this reason off-grid battery systems are niche applications where it is not feasible to run commercial power.

Here is the deal a 12 volt 15 amp pump consumes 180 watts. So if you run the pump for 1 hour then 180 watts x 1 hour = 180 watt hours. Next catch is battery systems are at best 50% efficient. So if you want to run the pump 1 hour per day your panel has to generate a minimum of 360 watt hours each day. Last complication is your location and what time of year you want to run the the thingy. If you live in Tuscon December Sun Hour rating is 5.2 hours. So you would only need a 360 wh / 5.2 h = 70 watt solar panel to get the job done. If you live in Gloomy Seattle with only 1.2 Sun Hours in December you need 360 wh / 1.2 h = 300 watt panel to get the job done. All that to generate 4 cents of electricity per day. So as you can see location and time of use matter.

So if price is a concern, then you are looking at the wrong option using solar, because with solar money is of no concern, and price is no object.

[trauts14]

I certainly appreciate your honesty and all of the help I have received here on solarpanletalk.com. The knowledge I have gained in the last 24hrs is huge.

Since I can most likely rule out a solar panel due to the expense, can anyone suggest a battery that i should look for? Does the battery still need to be "deep cycle" if i am not using a solar charger? I will look for a big battery (tractor??) and let that run the pump. I will then charge the battery when i go to the garden every weekend.

If anyone has any comments/suggestions as to how you would configure this setup, I thank you in advance.