Hi,

I am new to this forum and pretty new to offgrid solar systems as a whole. I am in some form of trouble and need some expert, but quick advise. So here we go.

I have a 600w load connected to a 4 * 100 ah battery bank which has been configured for 24volts. The battery bank is being charged by 800w panels(100w panels(12 volts) * 8) which is also set to 24volts. The charge controller which charges the battery is made by Rk Solar and has a digital display in the front to display how much percent is my battery charged at any point of time.

Before connecting the load to the system i just wanted to check whether the controller was perfectly or not. So i wired up everything except the inverter/DC output from the controller.

Now is the bizarre part.During daylight, ie from 9 AM – 5 PM the controller shows the battery charge climbing from say 40% to 100% within 6 hours or so. Once the sun goes down, according to the controller that battery charge climbs down from 100% to 30% or low in some cases with no loads attached.
The discharge occurs within an hour or two. The controller is pretty new and is rated at 24v/40A.

What might be causing this?