How many wattage of solar panel I need to diy to charge 12 volts 70 amps battery?

Kindly refer the supplied block diagram below.

frollard5 years ago
It depends on how quickly you want to charge the battery bank, how quickly you want to deplete the bank (discharge on your useful load).

You could use a 1 watt panel and charge a HUGE battery bank over a period of months.
You could use 10kW of solar panels to charge a small battery bank in a few minutes...

So the answer to your question is a question: how much power do you NEED?