I currently have 12 solar panels connected as below to a Axpert 5kva Inverter. +- 3.8kw of panes. 

However, In winter 2 of the panels spend most of the day in some shade. does anyone have a suggestion to re wire the panels to possibly omit the two end panels in winter. In summer it is not so much of a issue as the sun is much higher.

As you can see, this photo was taken at 12-30 and there is still shade on the two end panes

This is my first winter with this set up, and I know production is lower in winter. But my system is peaking at around 2.2kw and my total daily production is down from 15kwh to 9kwh on a clear day. is this normal for winter, or is it a result of the shading on my panels

Little bit more info needed - which inverter exactly? Seeing this is 3S4P wired I'm guessing one of the 145V max solar options? It's possible shading is an issue, but you also need to check you're not over-voltaging now with the cooler winter weather. Or that it's just a normal difference in winter with lower angles and less Sun time. I get 12kwh a day in summer (1.6kw peak) and 8kwh in winter (1.2kw peak). But my angle is 18° which is better suited for summer power (works well for me in KZN where I run Aircons all summer!)

Looking at your photo - no chance you can shift the panels slightly further from the wall? Can't see what's on the other side there. Oh nevermind - just saw they were mounted to the wall!

I imagine you'll still get better production from semi shaded 3S4P than the next alternative which is 3S3P.

The main problem is that a shaded panel affects all the panels in the same string.  In your case, you will lose a big part of the 6 panels in the 2 left hand strings.

You can kill 2 birds with one stone if you re-wire to 2S6P with the 2 offending panels in the same string. It will eliminate most of your shading losses and remove the risk of overvoltage damaging you inverter (I am assuming 145V max VOC inverter) .

Edited June 14, 20215 yr by Calvin

1 hour ago, charl said:

I currently have 12 solar panels connected as below to a Axpert 5kva Inverter. +- 3.8kw of panes. 

However, In winter 2 of the panels spend most of the day in some shade. does anyone have a suggestion to re wire the panels to possibly omit the two end panels in winter. In summer it is not so much of a issue as the sun is much higher.

As you can see, this photo was taken at 12-30 and there is still shade on the two end panes

This is my first winter with this set up, and I know production is lower in winter. But my system is peaking at around 2.2kw and my total daily production is down from 15kwh to 9kwh on a clear day. is this normal for winter, or is it a result of the shading on my panels

My panels are flat mounted and also going through my first winter. 

Summer clear day I would generate 60kwh compared to a clear winter day in getting 25kWh. This is with no shading on the panels. This is with 10.4kw of solar panels. 

Is the 15kwh your normal daily summer production? 35% drop from summer to winter is normal so I don't think the shading is causing as big an issue on your overall production. 

1 hour ago, Achmat said:

35% drop from summer to winter is normal

That is completely dependent on the tilt in your panels.  Flat mounted panels produce much more power in summer than in winter - tilt them at 40 degrees and the picture changes hugely.

Below is a graph comparing panels tilted at 0, 10, 25 and 40 degrees in July.  You will see that the panel at 40 degrees produce double what the flat one does.

The picture is of course very different in summer:

So you can see that for flat mounted panels the drop is 8.2 to 2.6, or 68%!  For panels tilted at 40% the drop is 6.4 to 5.1, or 20%.

These figures are for panels pointing North, in Cape Town.  It will vary a bit for other locations.

49 minutes ago, Calvin said:

That is completely dependent on the tilt in your panels.  Flat mounted panels produce much more power in summer than in winter - tilt them at 40 degrees and the picture changes hugely.

Below is a graph comparing panels tilted at 0, 10, 25 and 40 degrees in July.  You will see that the panel at 40 degrees produce double what the flat one does.

The picture is of course very different in summer:

So you can see that for flat mounted panels the drop is 8.2 to 2.6, or 68%!  For panels tilted at 40% the drop is 6.4 to 5.1, or 20%.

These figures are for panels pointing North, in Cape Town.  It will vary a bit for other locations.

Very much aware of that. Still don't know what his orientation or azimuth is in order to rule out if the loss is within the expected winter decline. 

I use this app to look at potential pv production for the day. Free version is fine to do a spot check. Enter your location, inverter and pv start sizes and it gives you a fairly good indicator of what you can expect over the next few days based on your location and weather forecast. 

https://play.google.com/store/apps/details?id=com.exigo.solcaster

Isn't this a good case for an optimiser that could eliminate the effect of the panel being shaded but maintain optimal generation for the rest of the panels.

 

But I don't have any experience on this.

 

Maybe someone can make some recommendations?

12 hours ago, branderplank said:

Isn't this a good case for an optimiser that could eliminate the effect of the panel being shaded but maintain optimal generation for the rest of the panels.

 

But I don't have any experience on this.

 

Maybe someone can make some recommendations?

Considering the price of optimisers, it's generally cheaper to just buy and place more panels (judiciously). Having said that, if roof space is limited and all other options exhausted, then optimisers do fulfill a role. 

Have you looked into power optimizers for the two panels? 

I saw a few a while back for like a grand each. 

Thank you all for your replies

My panels are on adjustable stands, I have them at 35 degrees now in winter, and dropped them to 15 degrees in summer. I think the best options would be to reconfigure my panels in 2S4P possibly even with a disconnect for the 2 end panels for winter. I'm not sure if they would drop the production of the entire system 

Unfortunately I don't have any more space on my roof at the moment, Ill have a look into the solar optimizer