Confused about panels

[cragster]

Hello everyone, this is my first post, I'm having a bit of confusion, so here we go, my system is, 4x 110amp batteries, (2nd hand old ) epever 40a, 4x 235 panels, now as i dont know much, i connected my panels ++++, and -----, at the controller, I get 30/34v and around 0 - 30+ amps, it all works fine, as I see it, Now, I went to look at a friend's, same sort of set up, but the controller is the newer model, and only 3 x 235w panels, but here's my confusion, the panels are connected +- +- +-, at the controller, it reads around 150v ( sorry never got to see the amps, it was pulling), I live in Greece, sun is mostly availble , so heres, what's confusing for me
1. Is the 2nd set up ok?
2. Is it better the 2nd way?
3. In the winter, it can be cold and cloudy, with out breaks of intense sun, , will this be to much power , for the controller to handle, ?
What I'm thinking is, can I connect, 2×2 panels +-, then connect , them 2 together ++ --, to the controller? My epever can handle 100v, where as the newer model can handle 150v.
As a summery, to my question, on cloudy days, I don't charge much, and wonder is there a better way?
I'm sorry if ,non of this makes much sense, but I have to learn from somewhere , and ask questions, I'm only sorry I found your forum ?, thank you for your time reading this suoer confusing thread, im just super confused.
Thanks Craig

 

[Mattb4]

Connecting panels in various series and parallel setups depends a lot on the requirements of your SCC and associated wiring has for voltage and amperage. The higher the voltage for a given panel watts the lower the amperage. It is the W=VA equation.

The other consideration is panel shading in that panels that are shaded draw down production more in a strictly series setup.

So to answer the questions:
1. If the second setup is working and the voltage is within the SCC ratings than yes it is OK
2. Perhaps
3. Panels do not push power. Loads draw power from the panels. Your SCC has limits and it is best to stay within and slightly less than maximum.

Regarding your summary. Yes cloudy days you will not get much production, this may be slightly improved by panel configuration and SCC setup. So long as you stay within the specs go ahead and try out other panel arrangements.

 

[MichaelK]

Some basic terminology and the 101 rule of electricity will help you a bit. You should the remember the basic electrical mantra, which is...

In series volts add while amperage stays the same. In parallel amps add while volts stay the same.

We can apply this to what you are seeing. With your statement "i connected my panels ++++, and -----, at the controller, I get 30/34v and around 0 - 30+ amps". What you are talking about is wiring your panels in parallel, or written in shorthand, 1S4P. So, the amps are adding up to ~30, while the voltage stays the same as one single panel.

For your friend's system "the panels are connected +- +- +-, at the controller, it reads around 150v" what you are describing is a serial connnection, so the volts add, while the amps stay the same. In shorthand that's 3S1P.

As a general rule of thumb, higher voltage works a bit better than higher amperage, assuming you stick within both the voltage and amperage limits of whatever brand of electronics you buy. In general, with higher voltage, you can get by with thinner copper wire, which can get quite pricy. The other big advantage of higher voltage is that you can run the DC power over longer distances, which will let you position the solar array in the very best position, rather than having them close to the batteries.

Keep in mind that the choices you can make are based partially on the type of electronics you buy. PWM charge controllers are dirt-cheap, but the voltage of the panels must be carefully matched to the voltage of the battery.

MPPT controllers act as a transformer, taking raw high-voltage solar (like your friend's system) and transforming down to battery voltage. MPPT controllers can cost a LOT more than the older PWM ones. You can typically make up for the extra cost by using higher voltage grid-tie panels, which have a lower $/W cost then 12V panels.