High wattage 12 v panels

[john]

Hi Guys, I have a question . I have 2 120w panels (12v 7amp) and I want to expand. I need more amps for charging . I was thinking of 2 -215w evergreen. They are max18v and produce 11amps each. If solar panels are just battery chargers why are there so many panels that are 12v cost so much money and do not produce high amps. I feel that is all I'm looking for,just amps.I have been doing this for a few years and wanted some input from others before I purchased more gear. Thanks

[Mike90250]

why are there so many panels that are 12v cost so much money and do not produce high amps

A 10 watt panel, is a lot less expensive than a 200W panel, but only produces .7 amps under good conditions.

Maybe I'm not understanding your question ?

[Naptown]

I have noticed the low watt panels are extremely expensive compared to a grid tie 240+w module

[Sunking]

$/watt goes way up when the wattage goes down.

[john]

$/watt goes way up when the wattage goes down.

Im sorry guys for being confusing. What I mean is I am looking for the highest amp 12 volt panel I can buy. I only see 3 or 4 that stay under 20 volts . But with that I get 11 amps . Most of the rest of the panels over 200 watts are of various voltages usually high 20's to mid 30's.With that you get as little as 3 and up to 5 amps.Why would you not go strictly for amps? My solar panels are battery chargers and I want amps . I just dont understand.

[Sunking]

Why would you not go strictly for amps? My solar panels are battery chargers and I want amps . I just dont understand.

Because it is foolish and inefficient. Watts is what you are after, not amps. Amps if a function of power and voltage.

All panels for 12 volt battery systems are going to have 16 to 18 volts @ maximum power. However with MPPT charge controllers you are not stuck with standard 12 volt panels. They allow you to use much higher voltages thus increasing the efficiency and less expense in wiring.

Those 12 volt panels @ 7 amps output 17.1 volts, not 12.

[tandrews]

This is basic stuff, but somehow needs to be understood in this thread.
One watt is the rate at which work is done when one ampere (A) of current flows through an electrical potential difference of one volt (V).

W = VxA

Each can be traded for another either thru planning and purchase or via a charge controller that can adjust one for the other to maintain an output.
as Sunking said "However with MPPT charge controllers you are not stuck with standard 12 volt panels"
They are related and forever vary each other.

Apologies if this is a slap of the obvious, but it seems to be missing from the original poster's reasoning.

[john]

This is basic stuff, but somehow needs to be understood in this thread.
One watt is the rate at which work is done when one ampere (A) of current flows through an electrical potential difference of one volt (V).

W = VxA

Each can be traded for another either thru planning and purchase or via a charge controller that can adjust one for the other to maintain an output.
as Sunking said "However with MPPT charge controllers you are not stuck with standard 12 volt panels"
They are related and forever vary each other.

Apologies if this is a slap of the obvious, but it seems to be missing from the original poster's reasoning.

Thanks guys , I'm still learning.So , in laymans terms,most quality panels of 2oo watts will put equal charge in
my batteries? If I use an mppt controller. Also can I put two equal panels into one mppt controller(appropriate size)?

[Sunking]

John go read this thread about controllers, it might help to understand a bit about what is going on.

[john]

Thanks again, very informative .I am getting an mppt for sure. Can I plug two panels into one mppt controller ?

[Sunking]

Thanks again, very informative .I am getting an mppt for sure. Can I plug two panels into one mppt controller ?

Of course you can, panels iss not limited, it is THE WATTS vs Battery Voltage vs Amps.


Example a 40 amp MPPT controller at a battery voltage of:

12 volts, max 500 watts
24 volts, max 1000 watts
48 volts, max 2000 watts