Advice on setting up a solar system

[Mike Hoxbig]

I don't think there's anything necessarily wrong. Afternoon production is much lower in winter than morning production.

Here's mine today on a north facing roof


Production drops significantly after 3pm. I'm currently on around 800w at 4pm with the domestic using the iron, so I'm drawing from grid.

Yours being east/west means your east roof is still getting decent sun after 12pm. But your west roof only starts ramping up after 12pm, and you would only get about 3 hours of decent sun before production starts dropping off.

Basically winter is a beetch. Wait until spring/summer to get a better reflection...

 

[wingnut771]

I don't think there's anything necessarily wrong. Afternoon production is much lower in winter than morning production.

Here's mine today on a north facing roof
View attachment 1322662

Production drops significantly after 3pm. I'm currently on around 800w at 4pm with the domestic using the iron, so I'm drawing from grid.

Yours being east/west means your east roof is still getting decent sun after 12pm. But your west roof only starts ramping up after 12pm, and you would only get about 3 hours of decent sun before production starts dropping off.

Basically winter is a beetch. Wait until spring/summer to get a better reflection...

 

[Snyper564]

Yeah also less my side just pumping up the geysers too

 

[sjm]

I don't think there's anything necessarily wrong. Afternoon production is much lower in winter than morning production.

Here's mine today on a north facing roof
View attachment 1322662

Production drops significantly after 3pm. I'm currently on around 800w at 4pm with the domestic using the iron, so I'm drawing from grid.

Yours being east/west means your east roof is still getting decent sun after 12pm. But your west roof only starts ramping up after 12pm, and you would only get about 3 hours of decent sun before production starts dropping off.

Basically winter is a beetch. Wait until spring/summer to get a better reflection...

I expect a drop in production in winter and also to generate less from the West string, but not to this extent.

Here's the Home Assistant forecast for today's production (green circled line was the expected output from the east string, blue circled line was the expected output from the west string).





Here's the actual output



Output is nowhere near what the forecast was. Today wasn't great as there were clouds in the afternoon, but the trend is the same as every other day since my installation.

 

[Koosvanwyk]

I expect a drop in production in winter and also to generate less from the West string, but not to this extent.

Here's the Home Assistant forecast for today's production (green circled line was the expected output from the east string, blue circled line was the expected output from the west string).



View attachment 1322756

Here's the actual output

View attachment 1322762

Output is nowhere near what the forecast was. Today wasn't great as there were clouds in the afternoon, but the trend is the same as every other day since my installation.

All it takes is for one cell on one panel to be shaded, what you describe sounds like the impact of shade?

Edit Shade will impact Amps while Volts will generally not be impacted. A PV panel needs light to produce Volts and direct sunlight to produce Amps, hence shade impacts Amps. Your MPPT tracker will be searching for the most effecient combination of A and V so there might be slight variations in Volts if a panel is shaded.

 

[sjm]

t takes is for one cell on one panel to be shaded, what you describe sounds like the impact of shade?

Would that not result in a voltage drop though?

 

[Koosvanwyk]

Would that not result in a voltage drop though?

See my edit to my post

 

[sjm]

See my edit to my post

Thanks. Will check for shading using a drone tomorrow

 

[Koosvanwyk]

Would that not result in a voltage drop though?

Found an old picture, PV 2 had one cell shaded at this point in time, caused by a chimney.
You see a slightly higher Volt ready on PV 2, that is the MPPT reacting to the lower A caused by the shade.

 

[sjm]

It does indeed look like shading. I was worried about trees and spent time making sure that they didn't cast a shadow on the roof but failed to consider the chimney.



Now to work out how to deal with this.

 

[Snyper564]

It does indeed look like shading. I was worried about trees and spent time making sure that they didn't cast a shadow on the roof but failed to consider the chimney.

View attachment 1323224

Now to work out how to deal with this.

Saw a neighbour with similar issues. First determine if its actually an issue. Half cell mono perc will deal with this ok so see if you have any really big issues first

 

[sjm]

Saw a neighbour with similar issues. First determine if its actually an issue. Half cell mono perc will deal with this ok so see if you have any really big issues first

I have big issues, the West facing string is producing less than half the power of the East facing string. That's what started the investigation.

 

[Snyper564]

I have big issues, the West facing string is producing less than half the power of the East facing string. That's what started the investigation.

Oh no that's terrible! That's some serious loss. I would check if those panel inverter or optimiser would work.

 

[RonSwanson]

It does indeed look like shading. I was worried about trees and spent time making sure that they didn't cast a shadow on the roof but failed to consider the chimney.

View attachment 1323224

Now to work out how to deal with this.

R629 @ Leroy Merlin.

 

[wingnut771]

View attachment 1323224

It does indeed look like shading. I was worried about trees and spent time making sure that they didn't cast a shadow on the roof but failed to consider the chimney.

Now to work out how to deal with this.

Can't you just chop the chimney very short?

 

[sjm]

Can't you just chop the chimney very short?

I guess I could, if it came to that. That'd be my last resort though, I'd prefer to leave the chimney untouched. Looking at the feasibility of moving the panel and my installer's also researching optimizers.

 

[wingnut771]

I guess I could, if it came to that. That'd be my last resort though, I'd prefer to leave the chimney untouched. Looking at the feasibility of moving the panel and my installer's also researching optimizers.

Yeah, optimizers would be the only option. I'm keen to see the real world performance as this would be the perfect case. There is not much info out there regarding these things.

 

[sjm]

First day that my production has been over 30kWh

 

[sjm]

Have generated over 2 MWh since installing the system in mid May and am fast approaching another milestone, where I'll have generated more power than I've imported from the grid since installation. Just need to generate 33kWh more than I import from the grid and I'll have achieved that

 

[RonSwanson]

Have generated over 2 MWh since installing the system in mid May and am fast approaching another milestone, where I'll have generated more power than I've imported from the grid since installation. Just need to generate 33kWh more than I import from the grid and I'll have achieved that

View attachment 1376635

Interesting goal, and it makes sense. Just goes to show that we all have different measures of success.