setting up my solar panel system to run my pump!

[ElideN]

THE BIG QUESTION IS HOW MANY 60WATTS PANELS WOULD I NEED TO RUN THIS PUMP 24/7?

so i have a 20 watt pump at 120V

60Hz if that helps with anything

using ohm's law: P = E x I

20watts/120V=.167 Amps

now my solar panel says:
powers: 12V 60 watt

60W / 12V = 5 Amps?

yet the rating says 3.5 Amps on the back because i know solar is inefficient in that aspect.

am i doing this correctly?

since the solar panel system uses a 12 Volts and not a 120 Volts

what do i do from there to figure this out?

[ElideN]

i have a ever last deep cycle battery... it last a long while before it drains all the way...

i want the pumps to run off my battery at night.

and use sunlight in the day.

[ElideN]

i need help to run my pond pump 24/7

THE BIG QUESTION IS HOW MANY 60WATTS PANELS WOULD I NEED TO RUN THIS PUMP 24/7?

i have a 250gph pump rated at 120v 60hz 20watts
i have a 60 Watt and a 120 Watt poly crystaline solar panel (total 180 Watts of solar panel)
i also got a duralast deep cycle battery from autozone 550ca at 90 ah
sunforce 30a controller for future-proofing
400watt modified power inverter


when i used my kill-a-watt meter and tested my pump on the wall i got 12.5watts and .19 amps at 120 volts ac, it works perfectly even though it draws low watts which is great...
when i plugged it up to my solar system i got around 10 watts .19 amp at 12 volts dc, it still works fine...
so i'd give it a 10-20watts peak.

so i multiplied 20watt x 24 hours = 480 watts required
and i know that a 550ca is a about 90 amp hours. i also know that don't want to discharge a battery below 50%.
To recharge that battery you've got about 4-6 hours of good sunlight to work since i am in texas... in winter! that is coming soon!, getting darker.
480 watts / 5 hours = 96 watts per hour.
and due to natural inefficiency i did 96w/.75= 128 watts of panel

will a 180 Watts panel work for this system 24/7?

and i have a 60 watt and a 120 watt will it work on this system?
am i doing this correctly?

[Pugo]

I am really interested in this project, As I am looking at the same thing, but to run a entire fish farm, granted it is a small farm, but I will have to run a couple of motors for one system and another small set for the fry and brood stock.. As they make 240w solar panels why not use those? I'm also interested in how many it would take to charge and run the system. So you will have to have double the power available during the day just to run your system at night.

[aman]

Hi ElideN
This is just my opinion but I would have thought you would be better off running a 12 volt or 24 volt pump.
If you use a 120 volt pump you will have to step thee voltage up from your batteries using an inverter.

This will add inefficiencies and added complexity to the system. You will loose power and there will be another thing in a critical system to go wrong.

If you built a completely 12 volt system you would be able to utilize many recycled from scrapyards etc

aman

[Pseudoreality]

Perhaps I can help you at here a bit. You seem to be jumping around units when you are doing your calculations. Before I start do you know for sure rated for 90 amp-hours? You mention you know that 550 cold cranking amps is 90 amp-hours. That is incorrect. Cold cranking amps is a measurement of how much amps your battery can pump out at a specific temperature to know if your truck will start in cold weather. Amp-hours is a measurement of the total amount of energy in your battery. For the purposes of my analysis I will say you have 90 amp-hours.

First off let’s calculate how much energy your pump will use in 24 hours. Its power consumption is 20 Watts. A watt is a joule per second.

24 hours x 60 minutes/hour x 60 seconds/minute x 20 joules/second = 1.73 x 10^6 joules

Alternative unites are 1.73 MJ or 0.480 kW-hours

Now your battery holds 90 amp-hours at 12V. The power formula I use is P=IV. Power (watts) is equal to current (amps) times voltage (volts). Now if we use the amp hours we can get total energy out of this formula in terms of kW-hours.
90 amp-hours x 12 volts = 1080 W-hours or 1.08 kW-hours.

Therefore it appears your battery should be able to run your pump for about 2 days before fully draining. There are losses when you convert from DC to AC, but you are more than double.

Now you say your solar panels are rated at 120 and 60 W. I’m not sure how they rate solar panels, but that number could mean maximum output if they are pointing straight at bright sun. For arguments sakes let’s say you get 50% of that rating for 8 hours a day.

180 Watts x 0.5 x 8 hours = 720 W-hours or 0.720 kW-hours

0.720 kW-hours > 0.480 kW-hours and therefore your solar panels should keep your battery charged up. The only thing I’m not sure is how much power you get on cloudy days. If it's black skies for a week you may have a problem. Use your meter on a cloudy day to tell me how much they are generating and then we can revise this estimate.

Good luck and keep us updated.