dirty solar panels, warm weather, lower power output?

ispookie666

Just to throw spanner in the works 
1. July 10th Max 27 Min 15 C during day light hours 


2. July 11th Max 30 Min 17 C (during daylight hours 


Looks like it's all over the place but maybe healthy panels produce less output 

Mikeyboy01443

I like that level of monitoring 🙂 but whats the deal with those 2 panels

ispookie666

@Mikeyboy01443 one of the panels went kaput last year and the other this April. Degredation is what I think. It's an Enphase system with submodule 250w mono black panels installed 2015. Not financially viable to replace them. 

Mikeyboy01443

No? My 390w panels were about 140 quid each - could you not upgrade them bit by bit adding more power? Or are you limited by the inverter?
Also if they are only approx 7 years old wouldn't they be under warranty if they have lost that much generation power?
Assume enphase is the inverter? Sorry not familiar with all the makes, solar newbie here

ispookie666

The panel warranties are not worth the paper they are printed on. 
I'll have to shell out scaffolding cost and the installer has shut shop.  I'm not sure the sequence of inverters/panels are correctly replicated. 

Add to this the complexity of FiT scheme and any change in panel size having a material impact. 

Finally, seeing how busy the installers are, not in a million years they will touch this. 

Spies

I think I'm seeing the effect of dusty panels, especially at low light, I've read it can reduce efficiency by up to 20%!

Alnat1

Pretty sure mine are affected by dust and bits of straw.

Bought the house because of the lovely view of fields and woods, never considered the muck and dust the farmer would send our way. At least it's only a few times a year.

Bring on the storms!! Did someone say Tuesday?

Pulpdiction

Pulpdiction said:

There's something in this, my system @ 3.5kw is generating around 2.6kw maximum and I've never cleaned he panels or even thought about doing so, I leave it to the rain.  However having completed 7 full years of solar generation I am noticing the regular 3.2kw generation is now very few and far between and usually it is on days with some cloud, not totally clear skies when temperatures are around 19/20 degrees.

Now a clean wouldn't hurt but I'm certainly starting to experience some slight degradation I think.  But my highest producing month has always been May - on average.  

Having posted the above I'm backtracking a bit now.  For the last few days I've seen my panels peaking at 3,300 and for about a minute the other day, not quite sure how this happened, but my inverter was reading over 3,600, not quite sure how as the panels are only 3.5kw in total.... but it was arounf 3,500 and then 3,600 for over 5 mins.... not sure if I should be slightly concerned as I've never seen the panels read above 3,340ish ever before in 7 years....

ispookie666

Panel level generation on the hottest day since install. Panel output for the damaged/degraded ones are seeing a significant drop compared to the unaffected ones. Nearly 2.4kWh lost generation. 

EcoScruples

I've been monitoring the last couple of weeks whilst the panels have had that horrible orange dust and dirt on them. No rain in that period here until last night and it wasn't that much, just a few showers.
Before last night the panels were doing about 3.8kwp 
Today they're doing 4.2kwp
So no cleaning by myself but he rain has definitely improved output.

I only get that much when my battery needs it though.