I'm working with some solar inverters that have a nominal voltage of 580V and an MPPT input range from 140V to 1000V. Each inverter supports two MPPTs, and my solar panels, arranged at a very shallow angle, consist of 20 + 19 + 2 units all oriented in the same direction. I'm trying to figure out what's conceptually better: should I use one single string connected to one MPPT per inverter, which would mean higher DC voltage and possibly lower resistance losses, or should I split the string into two, which may put me below the nominal voltage but allows me to utilize both MPPTs?
3 Answers
Using parallel strings can help if you're worried about shading issues because even small amounts of shade can seriously drop your output. But if all your panels are getting consistent sunlight, a series connection is likely to give better performance, especially in low light conditions like dawn or dusk.
Do you have any shading problems with your setup? It might be helpful to know how the amps are behaving as well.
The panels are facing south-south-west at a shallow angle. I cleaned the lower part of some panels recently, which made a huge difference! There's likely some shading from obstacles when the sun rises, but it's not bad enough to affect performance overall.
I'd go for the single string setup. It frees up the other MPPT for future expansion if needed. Plus, with higher voltage, you minimize the resistance losses which is always a good thing!
Agreed! Keeping it simple with one string sounds like the way to go.
Just a heads up, I can't expand my setup anymore since I already have more panels than the grid can take. So for me, it's all about maximizing the current options.
I also think the series setup is ideal for your situation, especially if you don’t expect shading issues. It can help gather more energy during those early morning hours.