question

@iostrym

https://www.victronenergy.com/mppt-calculator or

https://www.victronenergy.com/upload/software/VE-MPPT-Calc-3_4.xlsm

This is a good place to start. But generally speaking when connecting panels to one charge controller you would want to match them not have two different sizes/module types.

It is possible to connect them as you are describing, but not recommended. Check out this article on mixing panels.

https://solarpanelsvenue.com/mixing-solar-panels/

In series you need the max amps to be as close as possible & understand that the max amps is limited by the lowest value. Effectively you will have two panels at 5.59 amps.

In parallel you need the volts to match.

Yes it will work but you will effectively have two 185W panels.

Hello all thanks a lot for your answers.

I didn't understand your answers and this is because I was wrong when I said that solar pannel would be serially connected.I would like to connect them in parallel, not in serial. This is why I will correct my first message. sorry guy for all your answers.

I would like to avoid serially connection because I will be limited to the lowest value as you said. if one has no more sun, then it will shut off current even if the second one has a lot of sun.

Also I think I will buy a 350 WC solar pannel so I really don't want to be limited by current of the small pannel.

But I need to know if my undertanding about maximum current delivered to batteries is correct...

20A maxi delivered to batteries using 100/20, right ?

Also, is smartsolar 100/20 smart enought to limit by itself current to batteries at 20A or will the smartsolar 100/20 be damaged by too much current ?

ps : I'm not afraid of loosing current because I'm in a situation where there is not 100% sun on my solar pannel because there are badly placed (not in correct angle and exposition) so I'm not sure that I will really reach 350WC... But I need to understand exactly how it works.

@Alexandra, thanks for your link https://solarpanelsvenue.com/mixing-solar-panels/ but there is one part that I don't understand regarding parallel connection :

chapter : "Wiring solar panels of different ratings in parallel"

in this schematic, it is assumed that all solar panel are working at their maximum power point but it is impossible in parallel, as voltage would be choosen by charge controller to track maximum power voltage common to all solar pannel. it is impossible to have one panel at 17 V and other panel at 19V as indicated in the schematic. total current won't be 4x8A as other solar pannel will work at a voltage that is different to their own maximum power voltage. it will be the maximum power voltage of the complete system right.

So my point is :

- I agree that having identical solar pannel is the best. but it is impossible to do this if, like me, you add a new solar pannel 10 years after the first one.

- I agree that i will have maximum power if I buy a dedicated charge controller for each panel. (but I don't want to)

- with parallel connection : I have the feeling that adding a new solar pannel will be always better that keeping only the old one. and also I have the feeling that buying the new solar pannel + keeping the old one will give better result that keeping only the new one. => Am I wrong ?

And finally, what would be solar pannel specification to check if I want to minimize the power lost when using two solar pannel connected together in parallele regarding the power I could get if I connect each one on a separate charge controler. Only check Vmp voltage ? Is Voc important ? or cell numbers ? or something else ?