dirty solar panels, warm weather, lower power output?

Martyn1981

Just Have a Think and Engineering with Rosie (two Youtube channels I follow) made vids a couple of months ago looking at a new approach to the issue, as the older fluid cooled systems didn't work very well.

The Solar PV panel that provides electricity AND heat for your home!

Solar photovoltaic panels provide electricity for homes, businesses and utility scale grid providers. Ironically though, the hotter they get in direct sunshine, the less effective they are at producing power. So, what if we could harvest the heat, remove it from the panel, and do something useful with it? 'Killing two birds with one stone', if you like. Well...it looks like we've just worked out how to do exactly that.

Warming Up By Cooling Down Your Solar Panels

Energy use for heating is about half of the world's energy demand and 40% of global CO2 emissions. Currently, most of the world's heating comes from fossil fuels and traditional biomass. Modern renewable heat consumption supplies only slightly over 10% of the world's heat, and it is not increasing fast enough to keep up with global decarbonisation targets. In this video, we take a rooftop tour of a photovoltaic thermal technology, Sunovate, that cools down solar panels to make them more efficient, and uses that heat for heating buildings or industrial processes.

Matt_S_3

Early days I’ve had panels less than a week! It’s east facing but given the super sunny weather I’m surprised how low below potential of the panels I’m getting, 4,65kWh system is barely hitting 2kW looking at the individual readings eith

QrizB

Matt_S_3 said:

Early days I’ve had panels less than a week! It’s east facing but given the super sunny weather I’m surprised how low below potential of the panels I’m getting, 4,65kWh system is barely hitting 2kW looking at the individual readings eith

That is very low, even in this unusually warm weather.

Can you share some more details of your system? Do you get fancy-smancy graphs showing your output in real time or do you have to read the meters at the end of the day and work it out from there?

Martyn1981

Yeah, same here, struggling to break 2kWp, and seems to peak mid day at about 2.7kW. But, the daily totals are absolutely fabulous.

1961Nick

My filthy 4.00kWp system is currently generating 3.2kWh. A similar sunny but cooler day in April or May would see the generation clipped by the inverter at 3.7kWh for a sustained period.

Matt_S_3

QrizB said:

Matt_S_3 said:

Early days I’ve had panels less than a week! It’s east facing but given the super sunny weather I’m surprised how low below potential of the panels I’m getting, 4,65kWh system is barely hitting 2kW looking at the individual readings eith

That is very low, even in this unusually warm weather.

Can you share some more details of your system? Do you get fancy-smancy graphs showing your output in real time or do you have to read the meters at the end of the day and work it out from there?

It's a Growatt system, so I have data every 5 minutes via the app - it's this I've been looking at to see that I haven't even had a little peak near maximum.  Full details of system;

12 x JA SOLAR 380W MONO MBB PERCIUM HALF CELL

GROWATT SPH3000 HYBRID

GROWATT 6.5KW LV BATTERY

So Friday, Saturday and Sunday we generate 16, 11.7 & 16kWh.  Can provide more info if there are specifics worth looking at.  We've basically not used anything from the grid since installation which is great.  But I'm thinking ahead if we are this far below what I expected now then what will it be when there is less sun.

Pulpdiction

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.  

QrizB

Matt_S_3 said:

QrizB said:

Matt_S_3 said:

Early days I’ve had panels less than a week! It’s east facing but given the super sunny weather I’m surprised how low below potential of the panels I’m getting, 4,65kWh system is barely hitting 2kW looking at the individual readings eith

That is very low, even in this unusually warm weather.

Can you share some more details of your system? Do you get fancy-smancy graphs showing your output in real time or do you have to read the meters at the end of the day and work it out from there?

It's a Growatt system, so I have data every 5 minutes via the app - it's this I've been looking at to see that I haven't even had a little peak near maximum.  Full details of system;

12 x JA SOLAR 380W MONO MBB PERCIUM HALF CELL

GROWATT SPH3000 HYBRID

GROWATT 6.5KW LV BATTERY

So Friday, Saturday and Sunday we generate 16, 11.7 & 16kWh.  Can provide more info if there are specifics worth looking at.  We've basically not used anything from the grid since installation which is great.  But I'm thinking ahead if we are this far below what I expected now then what will it be when there is less sun.

Thanks for the info. You've got a 4.56kWp system and your generation for Friday, Saturday and Sunday was 3.5, 2.6 and 3.5 kWh per kWp - what this forum calls "O's". Most people on the forum have been producing 5 O's or more a day for those three days, so it seems like your generation could be ~30% below expected.

An east-facing system will produce less than a south-facing one; when modelled in PVGIS, and using a location near me in the central south of the UK, during July a typical south-facing system will generate 125kWh per kWp while an east-facing one only generates 118kWh. That's only about 5% and doesn't explain why you're falling short.

Do you have much shading of your panels, eg. from dormer windows or chimney stacks or trees? Anything else that might cause a reduction in performance?

(For examples of shade, see pages 10-12 of this MCS pdf. Some of those are quite extreme.)

Matt_S_3

Saw the Os wasn’t sure what that referred to.  No shading at all, I’d done a lot of my own calcs in advance so knew I’d be lower than stated being east facing but it doesn’t seem to be giving me what I expected.

I’d used the PVGIS modeller, just done again and it gave a overall loss of 19.29% and predicted July generation of 625kWh

Magnitio

QrizB said:

Matt_S_3 said:

QrizB said:

Matt_S_3 said:

Early days I’ve had panels less than a week! It’s east facing but given the super sunny weather I’m surprised how low below potential of the panels I’m getting, 4,65kWh system is barely hitting 2kW looking at the individual readings eith

That is very low, even in this unusually warm weather.

Can you share some more details of your system? Do you get fancy-smancy graphs showing your output in real time or do you have to read the meters at the end of the day and work it out from there?

It's a Growatt system, so I have data every 5 minutes via the app - it's this I've been looking at to see that I haven't even had a little peak near maximum.  Full details of system;

12 x JA SOLAR 380W MONO MBB PERCIUM HALF CELL

GROWATT SPH3000 HYBRID

GROWATT 6.5KW LV BATTERY

So Friday, Saturday and Sunday we generate 16, 11.7 & 16kWh.  Can provide more info if there are specifics worth looking at.  We've basically not used anything from the grid since installation which is great.  But I'm thinking ahead if we are this far below what I expected now then what will it be when there is less sun.

Thanks for the info. You've got a 4.56kWp system and your generation for Friday, Saturday and Sunday was 3.5, 2.6 and 3.5 kWh per kWp - what this forum calls "O's". Most people on the forum have been producing 5 O's or more a day for those three days, so it seems like your generation could be ~30% below expected.

An east-facing system will produce less than a south-facing one; when modelled in PVGIS, and using a location near me in the central south of the UK, during July a typical south-facing system will generate 125kWh per kWp while an east-facing one only generates 118kWh. That's only about 5% and doesn't explain why you're falling short.

Do you have much shading of your panels, eg. from dormer windows or chimney stacks or trees? Anything else that might cause a reduction in performance?

(For examples of shade, see pages 10-12 of this MCS pdf. Some of those are quite extreme.)

It looks like a 3kW inverter has been installed, which seems quite a low rating for 4.56kWp. At this time of year you would expect it to max out at the full 3kW on a sunny day. I wondered if only one string of 6 panels had been connected to the inverter, but that would suggest you would have achieved 7, 5.2 and 7 O's which is possibly too good for your panel orientation.