Hi guys,do any of you have a east and west solar array? I want to increase my solar array, but because we live on a mountain the front legs of my structure will have to be 5,7 meters long to get the correct angle. On a east and west array the angle is much shallower.
Can you do a N-E + N-W instead? I think that would be optimal for self-consumption, as long as you have enough MPPTs.
You don’t need more MPPT’s. As long as each string faces same direction you can have them on same MPPT. I have a east/west setup that does just as well as my north only setup and if I had to redo I would have just gotten one MPPT and put everything on it.
there is a thread on this already will try find it
Your description is not very clear on what you mean exactly, but by having them all on one MPPT, you could be leaving a lot of kWhs on the table, depending on a number of factors like the MPPT algorithm.
Nope, you don’t.
If you study a panel’s VI curve, I is not proportional to V.
A panel attains full voltage under meager light.
I am going to explain this with a very extremist example.
If I had an identical E panel and a W panel. I am going to simulate a very extreme morning by covering the W panel with a blanket. The MPPT will still zero on the correct voltage based on the E panel.
Similarly, I can simulate an extreme evening and the MPPT will still deliver the correct max. power.
Now let’s consider noon, well, then both panels are delivering, and the MPPT picks a voltage that delivers the max power, which just happens to be spot on for both E & W panels.
So let’s consider the mid-morning when the E panel is at 75% power, and the West panel is at 25% power.
So the MPPT will favour towards the tracking voltage of the E panel, which will be slightly higher than the W panel, right?
This is where the VI curve comes in. You will see there is practically no voltage difference between the E panel at 75% I and the W panel at 25% I.
Keep in mind the tracking voltage will still be between these two voltages favouring the E panel as well.
It boils down to that it is a very efficient way to keep an MPPT working for longer in the day an not have to buy a second MPPT.
The low-hanging fruit is to buy extra panels with the saving you made by not needing a second MPPT. That’s put a lot of kWhs back on the table.
Germany pioneered East West arrays on the same MPPT over a decade ago. The proviso being each array is the same size with the same electric characteristics (same model panels) and that the tilt is ± 15⁰. Losses are limited to about 10% of a South facing array (Northern Hemisphere).