24 volt solar panels and 12 volt batteries. A way to step them down?

TentEnKaMan

Is it a stupid question to ask; 'why use 24v and not 12v solar panels' ??

Maîneÿ . . .

You should be able to get "12v" panels, but if not, almost all MPPT type controllers will take in 12 - 96V plus panels and convert it to the 12v battery charging voltage. They are more efficient too.

They are available from about $80 from solar steve and ebay to $lots with 60 - 80 amp capacity.

Hi Tent ( or should that be Mr Enkaman?),

As Boobook indictaed, the device you're looking for is a Maximum Power Point Tracking controller (MPPT). These controllers take the panel input current at the voltage that gives the maximum total power (volts x amps) and electronically converts it to the correct voltage for battery charging (or powering a bore pump etc.)

For a nominal 12V panel the MPP is at about 17 or 18 volts, for a nominal 24V panel it will be 34-36V. So an MPPT controller able to accept at least 48V input and provide a nominal 12V battery charging output will do the job admirably.

Any of the specialist solar equipment suppliers should have a few to choose from.

Ian

Hi Tent

I am not sure what wattage panels you are looking for, but suitable panels are readily available up tp 120 watts
They usually have an open circuit volts of around 21volts & are the correct ones for charging 12v systems
Peter

Hi thanks to everyone for the advice =D It is very much appreciated.

Miainey, the reason I was looking at 24volt panels is because they seem to be whats available more on ebay at large wattages and reasonable prices.

I already have a 12v 1000w pure sine wave inverter so this is yet another reason i didnt want to step up to 24v as replacing this with another pure sine wave inverter would be a costly exercise im sure and the $$$ are running low after spending a thousand on 3 new AGM'S after my old ones died. Now the gennie has died too so Im not really able to afford to pony up for a new inverter atm

The MPPT controller (or whatever it was, i dont have your replies in front of me atm, as i didnt post this as a follow up...) sounds like it may be what i need. Thanks for the suggestion and to everyone who has helped.

I think someone asked what panels i was looking at so ill answer that now too.. They were 2 x 185 watt panels but in the 24v format.

Sorry if ive missed anything if i have ill try to add a follow up. I have to brief coz my gennie has also blown up and have to wait a weekish for new honda one coming. So I can only scratch my batts atm as my 650 watt backup gennie wont even come close to bulk charging on my 50A charger..... lol... had a good run I have....

Thanks again all and all advice is still welcome please. Partic from people who have experience or knowledge of a guide to installing them on a caravan roof =D

TentEnKaMan is a little Tutenkaman joke to the person who asked what to call me. Im not fussed just grateful for your advice