Advice on solar charge controllers please

[andysmith]

Hi All,

I have two banks of solar cells, each rated at 1kW @ 12V. I also have an inverter rated at 2kW which can work with an input voltage of 12V or 24V. I also have four lead acid batteries which are rated at 100Ah and have a nominal voltage of 12V. I can configure my system to be a 24V system (with the panels in series and with the batteries in series/parallel) or to be a 12V system (with the panels and the batteries in parallel).

By my calculations I need a charge controller rated at greater than 80A. And alas, whether I opt for a 12V system or a 24V system, this rating remains the same. My problem is that I cannot obtain such a large controller locally (the largest available to me is 80A, which is a bit small) and I cannot purchase from abroad due to the excessive penalties and because of the time it takes. Also, the locally obtained controllers are simple and do not have a master-slave facility. My local solar vendor tells me that I can buy several smaller charge controllers and wire them in parallel. As someone who understands the way feedback works, my feeling is that this is very dangerous for the equipment.

So, my question is: Is there any way to complete my system using the small and simple charge controllers which are available to me locally?

Thanks in advance

[Sunking]

Andy you have already answered your own question. However you have some facts mixed up. I can only assume you are looking at MPPT Controllers, at least I hope so because you are well beyond PWM controllers. PWM is antiquated. Anyway to my point Assuming you are talking MPPT Controllers OUTPUT CURRENT = PANEL WATTAGE / NOMINAL BATTER VOLTAGE. Example 1000 watts / 12 volts = 80 amps. Based on that knowledge then you can determine the maximum panel wattage vs battery voltage, So an 80 amp MPPT controller maximum input wattage vs battery voltage is:

1000 Watts @ 12 volt battery
2000 Watts @ 24 volt battery
4000 watts @ 48 volt battery.

You say you have 2000 watts of panels. Figure it out. I will give you a hint. If you insist on Toy Voltages of 12 volts, you need two expensive 80 Amp MPPT Controllers.

[andysmith]

Sunking, thank you for your reply. I understand the points you make but you haven't answered my question: how can I make a system with the material available here. I am not aware of any source locally that can provide an inverter for 48V. And I'm pretty sure I won't find a charge controller here that handles 48V.

[Sunking]

Who said anything about 48 volts? With a 80 amp controller you can run 2000 watts at 24 volts or 48 volts. Take your pick.

You will need a 80 amp controller that has a 150 Voc input. Run the panels as high of a voltage as you can like 4 panels in series.

[Logan005]

"Here" is relative, you are online, easy to find 24, 36, 48 volt inverters, chargers, pumps, lights and motors of all sort. only thing I source locally are batteries. everything else comes from e-bay sellers and the like.

[andysmith]

Thank you Logan for your reply. Alas, as I stated in my question, in The Philippines the postal service is so abysmal it could take months to get something. Additionally, the government will slap a very large 'fine' on anything that looks a bit technical, so eBay is out of the question. We have our own substitute for eBay here; it's called OLX. But on OLX there is a very limited choice of inverters. As I said.