What size solar panel should i expect to buy to keep a deep cycle battery charged.?

Question

My plan is a remote garden. I want to have a solar panel hooked up to a couple deep cycle batteries, then to and inverter, then to a timer, then to a water pump/ webcam. The concept would be to plant a garden on land i own, and have the water pump turn on once a day for a half hour or so to pump well water to the garden. and possibly expanded into a weather station with a basic PC and weather monitoring sensors. What sized solar panel should i buy to maintain a charge in the battery? and does this project sound feasible to anyone else?

Answer 1

I think you need to tell us more information. But I'll make some guesses.

Note that you will need a charge controller between the solar array and the batteries.

Find the amount of power the pump uses, and number of hours per day, and that will get you the amount of energy. The pump may be, eg, 200 watts, and used 1 hour per day, so that is 200 watt-hours per day.

How many days without sun are you allowing? Too many and the batteries have to be very large.  

Assume one day without sun. Then you need 400 watt-hours of storage, 2 days. That is one medium sized lead acid battery, a large one is about 1000 watt-hours. I'd get the large one for future expansion, and also losses in the system.

So you want to charge 1000 watt-hours of battery in how many hours of sun? assume you get 8 hours of sun a day. So the solar array has to deliver 1000 watt-hrs in 8 hours, or 125 watts. Not too large.

You need a 200 watt inverter. I'd get one a bit larger, it doesn't cost much more.

You can adjust the numbers... email me if you need more info.

Answer 2

It sounds feasable to me.  You should determine the maximum power consumption of all driven devices and at least double it to determine the killowatt-hour output necessary.  Then shop for solar panels based on this output.