i have 6 panels set up on my roof for the last 3 months. In the winter, the 3 bottom panels get fair share of shade and for this reason i asked to install optimisers on them. I can only trust this was done, as i have no way of getting on the roof and checking it myself.
Now, my problem is that on sunny days the whole string is basically shutting down, and i'm getting 20watts out of it as soon as there is shade on the bottom row. Funny enough, on cloudy days, the production isn't great (time of the year obviously) but much better than sunny days. That goes against logic if you ask me. My installer says that on sunny days the optimisers are struggling to keep up with power produced by un-shaded panels. Is he right? I thought the job of optimisers was to eliminate exactly this effect. I also noticed voltage goes up, while current goes down to 0.1Amp when this happens. Any ideas?
Helps to know your orientation & slope of roof? Just so people can mentally visualize it
On the surface, your logic sounds good Yourmama. Sounds like something is off there. One thing that it could be however as a cause to the problem is that you actually have shading on more than the 3 panels that you thought? If you had a 4th panel shaded, it would be the reason why the string was "brought down" as you don't have optimizer on that guy.
Alternatively (and this should be unlikely as they should have checked!), they wired the optimizers onto one the wrong panels ?
On a "cloudy day" with no shading issues your panels will perform better as it's dealing with more diffused light than direct sunlight, so there doesn't tend to be the same effect.
But yeah, does sound like something wrong. Your sunny days should be 3-4x times output. Include the chart if you can on a sunny day from your inverter.
orientation is south, slope is about 25-30 deg. The shading is caused by next door roof and on sunny day i can clearly see it is only covering panels with optimizers installed. To be honest I think they didn't install optimiser on one panel, or somehow wired it incorrectly. I even have my candidate which one it might be. I attach graph from yesterday where there was no sign of cloud all day long. I only got some power generated in the morning and then nothing for the rest of the day. On cloudy day i would have drop around noon, but then a bit of recovery later in the afternoon. It was at very low from 11am on yesterday until sunset.
Yeah agreed, that doesn't look right. On the plus side, it maybe a temporary thing where the shading is only happening at this time of the year. As we progress into Feb-March with the sun being much higher from the horizon, it's unlikely that the shading of your neighbors house will affect you as it is here. (Bear in mind that I've not seen your house position in relation to your neightbor so I'm speculating) So it maybe a temporary thing that resolves itself over the next few weeks.
That said - if it was me, I'd attempt to get it fixed. You've paid for optimizers for a reason - doesn't look right to me.
yeah, i will push the installer to return.
I'm still confused why it works better on cloudy days though.
That part is easy to explain actually. So when it's a cloudy day, all the panels effectively receive the same amount of light as it's "diffuse lighting" which is illuminating the panels - you can think of it sort of like that there is no "shading" per say in play
The problem which the optimizers tries to overcome is that when a panel gets more light the internal electrical resistance of the panels change. So if you have 1 (or more) panels which have significantly more light, the resistances of those panels is much different. Optimizers effectively create an "alternative pathway" for the array to work.
Yours however are wired arseways or the wrong panels are optimized.