Which kind of batteries I need ?

[rdlrn19]

Hi

I create 2 solar panels of 18volts approximately, 63 watts and I would like to wire these 2 solar panels in series:

36 volts
126 watts

So I want to know which kind of batteries do I need to buy?
Do I need to buy a solar charger or not?
Which type of inverter I need to buy?

Thanks in advance

[Mike90250]

Lead-Acid, deep cycle batteries would be the right item. 2, 6V golf cart batteries are a good starting point.

What is the load going to be? 12V lights, fans, inverter for a computer ? Many things for 12V, fewer for 24V.

You would need a charge controller.

[rdlrn19]

My problem is that I'm newbie and I don't know exactly if connect the solar panel in series or not?

Because I would like to have the maximum amount of watts possible but the volts increase. Do you recommend to keep the load to 12v instead of 24v ?

[rdlrn19]

What could I load with a solar panel that has 18v 3.5 amps and 63 watts?

[Sunking]

How you configure the batteries either series or parallel is mainly determined by the type of charge controller you have, and what system voltage you choose to use.

If you use one of the older PWM or Shunt Controllers, they are generally made to operate at a specific voltage of either 12 or 24 volts. If you buy one made for 12 volts would require you to wire them in parallel. Likewise one made for 24 volts would require you to wire them in series.

If you use one of the newer more effecient MPPT controllers you have more fleibilty and can take advantage of operating at much higher panel voltages effeciency. For example you can wire your panels in series to = 36 volts but operate the battery at 12 volts. If you were to add another panel wire it in series to go up to 54 volts and keep the battery at 12 volts if you wish or move up to even more efficient 24 volt battery system with a flick of a switch and adding another battery in series. .

[Mike90250]

If you use one of the newer more effecient MPPT controllers you have more fleibilty and can take advantage of operating at much higher panel voltages effeciency.

I think this is not so much the panel working at a higher voltage that makes the panel more efficient, but for the same watts, higher voltage = less amps, and with less amps, you have less loss in the same size copper wire.

20V @ 10 A =200W
60V @ 3.3A =200W

3 A wire cost less than 10 A wire

[Sunking]

20V @ 10 A =200W
60V @ 3.3A =200W

3 A wire cost less than 10 A wire

I would not bet on that if you are installing per NEC because the smallest guage wire you can use is 18 AWG which is rated up to 18 amps, so a 10 amp wire is the same gauge as a 3.3 amp wire. FWIW I would never use NEC tables to select wire sizes to start with. From the panels to the controller I would design for a 2% of less voltage drop.