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jeepster avatar image
jeepster asked

Solar panels on diferent aspects of a property - multiple mppt

hi all, just in the research stage of building a off grid solar for my home office, hoping to build a 24v system with lithium batteries, victoron inverter and 4 *320w panels. I work from home and use the office from 8am to 6pm 5 days a week, i am in the uk. The house garden faces south but unfortunately thats the house gable and not the roof. my summer house roof faces south east. I am thinking of putting 2 panel on the summer house roof and 2 panels ( for now) on a pergola that we have that is facing south, Our house is in an elevated position and gets a lot of sun. My question is this, i assume that i will need 2 seperate mppt charge controllers, one for the summer house panels and one for the house panels, these are the panel specs, current at max 9.59 amp, volt at max 33.4v, short circuit current = 10.15amp, open circuit voltage 40.9 , i am going to purchase a victron 24 volt inverter and 2 or 4 lithium 12 volt 100amp batteries, any recommendations on victron charg controllers , i assume it will be more efficient to use 2 of them , one for the pergola south facing panels and one for the south east facing panels

MPPT Controllerssolar sizing
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2 Answers
Mike Dorsett avatar image
Mike Dorsett answered ·

The industy accepted paractice is htat if there is a difference of more than 5 degrees in azimuth or elevation between strings (of PV modules) then a different MPPT tracker should be used. This rule can be relaxed some, but it looks like your difference will be larger than this. So for your MPPT, you will be looking at about 26 - 27A for 2 modules at 24V. So the 1000/30 or 100/50 would do. Move up to 150V, if you think you might add more solar later.

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jeepster avatar image
jeepster answered ·

Hi, thanks for taking the time to get back to me, I bought the 100/50 and 2 *250w panels, voc of 27.9v for now, weve also bought a victron 3000kva inverter and 4 lithium batteries. Going to order 4 more panels, these will be perlight 400w, 49.5voc , again these will be wired in series in 2 seperate stings each with its own victron inverter. the short circuit current is 10 amps. Looks like i am going to be spending a lot on inverters.

2 comments
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nickdb avatar image nickdb ♦♦ commented ·
Why do you want another inverter? You just need another mppt which will connect to your existing inverter and be managed via dvcc.
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jeepster avatar image jeepster nickdb ♦♦ commented ·
Sorry meant mppt -
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