advice regarding the performance of my solar system

Stevegeraghty

Hi folks, I’m looking for a small bit of advice regarding the performance of my solar system.

I have 11 430w panels, 8 are due south facing and 3 are north facing.

My next door neighbour also has 11 panels, his house is SSE facing, with 7 panels on the front and 4 on the back, he also has a bit of chimney shadow.

On paper I should do better than him regarding production yet not once have I even matched him never mind do more.

I contacted the company who installed them with screenshots of the app on a good sunny day when both houses were empty wondering if maybe one of my panels maybe weren’t working but they completely dismissed me.

Any advice 

con747

https://www.boards.ie/discussion/2058355662/advice-regarding-the-performance-of-my-solar-system

Have a read of the last page of this thread.

https://www.boards.ie/discussion/2058101518/solar-pv-hints-tips-troubleshooting

graememk

Gonna need some numbers/graphs.

Are they the same size panels on power output, have you different inverters?

The 3 north facing, are they on optimisers or a different string?

Stevegeraghty

no optimisers

Same size panels

Same inverters solis

I don’t know if mine are on the same string or not

screenshots from the app, mine is left

JayBee66

String would refer to your panels being on PV1 or PV2. You should have two inputs on your inverter with the south facing panels going to one input and the north facing panels to the other. You'll need to follow your cables from roof to inverter to determine which is which. The north and south panels should be on separate strings.

If your graph shows production then there is quite a steep drop after local midday (about 1:30PM summer time). This suggests shading to me or some other problem, which is pulling production down.

My installers never believed a word I said when I could see from day 1 that there was a problem. It took me a year to sort it out for them. One Comp. Sci. degree versus three Electrical Engineering degrees. Logic won!

Stick with it. The data will lead you to a solution.

conor_mc

In the SolisCloud app, go to Device > select your inverter > select Parameter on the chart section > select “MPPT1 (kW)” and “MPPT2 (kW)” from the DC Power section. You should see both arrays generating at different rates.

Agree with others, 3x unoptimised North-facing panels probably aren’t getting up to startup voltage. Easy enough fix for your installer though, 3x optimisers should only cost them 150e or so, plus their time to install them. I would argue against accepting that cost yourself, since they haven’t really specced this setup properly.

edit: you can also check DC voltage on each MPPT.

bullit_dodger

https://www.boards.ie/discussion/comment/122252278#Comment_122252278

Not seeing the problem. You generated 21.3kwh on the screengrabs you supplied, he generated 22.6Kwh. Only 6% difference and the charts show roughly the same max outputs.

The day in question it was obviously sunnier in the early part of the day. I'm pretty close to you in Dublin 16 and my own telemetry has….

With your panels being south, and his being SSE, he was getting his panels in the direct sunshine earlier that you….on a day where it was sunnier in the morning.

That's not to say there isn't a problem, but it's perfectly explainable. It would be interesting to see what your outputs were on a day with perfectly smooth curves. You can do the math if needed , but it's a lot easier to compare across aspects when it's a clear sky all day.

wandererz

Dude,

Your solar system is also my solar system.

It's been doing well for the past 4.5 billion years.

I'd say that's pretty darned good.

Just leave it alone.

Stevegeraghty

@conor_mc does this mean everything is on the same string?

It’s not really about how much I generate, it’s the fact that next door makes more even though I have an extra south facing panel. It’s really not about “my dad is bigger than your dad!” I just have a gut feeling something isn’t working properly 🤷🏻‍♂️

graememk

https://www.boards.ie/discussion/comment/122253247#Comment_122253247

What was mentioned earlier, SSE will catch the sun sooner, especially in summer. You can see it in the graph, in the morning where the SSE has the edge.

Neighbours would drop off more as the afternoon progresses and yours would generate more for a bit longer.

Although them 3 north panels,

Would you be able to pull up the power (or even the voltage/current) graphs for that string.

I'm doubting that they are even starting.

conor_mc

Zero voltage on PV2/MPPT2…. but if I look at your PV1 peak, it’s about 4.5kW. 8x430 panels should only peak at 3.44kW, 11x panels would give you 4.7. So I now think they’ve all been put on one string.

But if you’re generating as early as 4:30am-ish, I think there must be optimisers installed somewhere, at least as far as I understand it. Otherwise the shaded north panels will pull down the overall array power until the sun is high enough to clear your roofline and illuminate those panels.

Stevegeraghty

they are going to come back and test the system for us

I’m not sure what that entails but at least they are engaging with me

conor_mc

Fingers crossed so. If there are already optimisers installed on the north-facing panels, I’d be asking them to split them from the south-facing panels and put them on MPPT2 (assuming you’ve not got roof space /plans for another array down the line). Good luck with it!

graememk

https://www.boards.ie/discussion/comment/122257736#Comment_122257736

3 panels on the second mppt would hardly be enough to start it.

conor_mc

https://www.boards.ie/discussion/comment/122257759#Comment_122257759

I did say if optimisers are already installed

slave1

I'd almost abandon those 3 off the inverter and put in a micro inverter instead of optimisers

conor_mc

I wouldn’t if there’s a string to spare, there are NC6 concerns with multiple inverters and also just the inconvenience of not seeing your production stats in one place.

JayBee66

I wouldn't be adding anything to the system. Leave it as is. Get the installers to prove the panels are split north and south on PV1 and PV2. If not then get it done. After that, see if it makes a difference. If not then you can add things like optimisers. Keep it simple and work your way up. Most installations are vanilla and do just fine.

The main thing is to have panels with different orientations on different strings. Otherwise, shaded panels can draw down unshaded panels, which is what might be happening here.

DC999

https://www.boards.ie/discussion/comment/122257759#Comment_122257759

I've the exact issue. 3 on tiny S roof. The string does start but much later than expected and goes to sleep much earlier. So my issue is different, it works just lower output. I can see the voltage spike a few times each day when it tries to start up and eventually it gets enough to start + and stay up. Installer knew that but just didn't even flag it to me - arghhh! That ship has sailed as it's lie 2 years now, so it's staying as is