Direct parallel connection of 2 EAST and WEST PV solar strings with (very) different panels and voltages?
published: 22/11/21, 13:21
Is it possible to parallel 2 solar PV strings with different voltages in direct connection? That is to say 2 strings made with photovoltaic panels of very different voltage and power?
Indeed, there are MC4 parallel connectors so a priori it is very easy to put 2 stings in //:
The panels are dioded, so normally there is no return of current in the weakest string ... but I still ask myself the question: what happens when a string let's say made for nominal 150V receives 300V at its terminals?
And when these 2 strings produce "a little" (around noon for example) with these 150V voltage difference?
What would happen? According to the basic laws of electricity, the weaker string will not produce anything at all ... Is that it?
It is as if we put 2 batteries including 1 used in //: all the current would be supplied by the strongest but the overall voltage would be lowered by the weakest. In the end, the strong battery alone would work better ...
We can see a lot of houses without roofs in the south with 2 strings 1 east and 1 west ... so if direct paralleling is not possible, you therefore need 2 inverters so 2 completely independent circuits?
That's it ? So the MC4 parallel connector is only used for the same orientation / same string of the same panels? But even in this configuration, it is possible to have solar masks on one thong and not on the other ... and therefore the same concerns of restraining the production of the strong thong would arise ...
In short, it's not very clear ... if someone who has more PV experience than me could explain to us?
Indeed, there are MC4 parallel connectors so a priori it is very easy to put 2 stings in //:
- connectors-de-derivation-mc4-males.png (125.21 KiB) Viewed 14309 times
The panels are dioded, so normally there is no return of current in the weakest string ... but I still ask myself the question: what happens when a string let's say made for nominal 150V receives 300V at its terminals?
And when these 2 strings produce "a little" (around noon for example) with these 150V voltage difference?
What would happen? According to the basic laws of electricity, the weaker string will not produce anything at all ... Is that it?It is as if we put 2 batteries including 1 used in //: all the current would be supplied by the strongest but the overall voltage would be lowered by the weakest. In the end, the strong battery alone would work better ...
We can see a lot of houses without roofs in the south with 2 strings 1 east and 1 west ... so if direct paralleling is not possible, you therefore need 2 inverters so 2 completely independent circuits?
That's it ? So the MC4 parallel connector is only used for the same orientation / same string of the same panels? But even in this configuration, it is possible to have solar masks on one thong and not on the other ... and therefore the same concerns of restraining the production of the strong thong would arise ...
In short, it's not very clear ... if someone who has more PV experience than me could explain to us?
