Suitable controller

Bunghole

Hi I have three 130 watt PV panels connected to three 120 amp/hrs deep cell batteries using a basic 36amp controller (the 3rd one in about 2 years of use) the previous two ran the batteries down and this one seems to be doing the same. I am connected via a 2000 watt pure sine wave inverter and mainly run a small circulation pump and a number of 240v LED lights in my seldom used off grid cabin. Can anyone advise me on which controller I should use for this system. Cheers.

BB.

Welcome to the forum... Can you tell us a bit about your system?

Roughly, where is it located (UK/Ireland?)
Do you run the inverter when you are not there?

A 2,000 Watt AC inverter is pretty big for a 360 AH @ 12 volt (?) battery bank. Closer to a 1,000 - 1,500 Watt AC inverter would be about the maximum for that size battery bank. And if you can get to a much smaller AC inverter (like 300 Watts).

And, depending on where you are at--Say Dublin--You may not get much sun:

http://www.solarelectricityhandbook.com/solar-irradiance.html

Dublin
Average Solar Insolation figures

Measured in kWh/m2/day onto a solar panel set at a 37° angle from vertical:
(For best year-round performance)

Jan	Feb	Mar	Apr	May	Jun
1.08	1.79	2.48	3.42	3.91	3.76
Jul	Aug	Sep	Oct	Nov	Dec
3.70	3.42	2.93	2.06	1.42	0.94

So--This time of year--Dublin gets about 1 hour of sun per day (January) average. An off grid power system with 390 Watts of solar would generate:

• 390 Watts solar * 0.52 off grid system eff * 1.06 hours of sun (Jan) = 215 Watt*Hours per average January day

That is running a 2,000 Watt inverter (at full power) for 6 minutes per day... And a 2kWatt AC inverter may run 10-20+ Watts just turned on... If you left it running 24 hours per day, that could use up all of the solar power (and then some) without running any other loads:

• 20 Watts Tare load (Inverter) * 24 hours per day = 480 Watt*Hour per day

If you do not have any loads (everything turned off)--Then a week of weak January sun may give you some "useful" power for a weekend.

-Bill