Hi All, 

Thanks in advance for helping me out. We installed 8kw Sunsynk inverter and 2 x 5 KwH Sunsynk batteries during load shedding. Happy wife. Our house is surrounded by lots of trees and we didnt want to cut down. So inverter and batteries were sunken cost. But now Electricity costs have gone up - and I now had some disposable cash to be able to buy panels. 

I have now installed 9 x 545w JA Solar panels.

5 panels on the NE-facing Roof. 1 panel is shaded for part of the morning. Zone B

4 Panels on the NW facing Roof.  Zone A

Yes - it helps - but I'm not getting what I expected. My limited research tells me it may be because too few panels on a string. I did the panel calculator based upon inverter and panels - and it tells me a minimum of 3 panels to get to the 150W needed. Maximum is 9 panels per string. 

Need your advice on how I should install more panels.  I have an area above the garage that could take 4 more panels. But - it is South sloping by 5 degrees - so would put brackets to lift the panels up to 20 degrees to match the existing panels. 

 Do I add the 4 panels to Zone A - so MMPT2 has 2x strings of 4 panels?  Or since in same orientation and angle - add them so that string has 8 panels on it? 

Looking at the specs - I believe that I could probably add Zone C to Zone A in Parallel - as each panel maxes out at 13A - inverter can handle 26A. Or should I rather push the Voltage higher with 8 panels in Series? Advice please.

I get 5-6 hours of generation a day in September. (making about 20kWh / day off Panels in A and B

Would really appreciate your input and advice. 

 

Pic of House from Google Earth. 

 

 

Edited October 28, 20241 yr by ErwinB
Typo

9 hours ago, ErwinB said:

Hi All, 

Thanks in advance for helping me out. We installed 8kw Sunsynk inverter and 2 x 5 KwH Sunsynk batteries during load shedding. Happy wife. Our house is surrounded by lots of trees and we didnt want to cut down. So inverter and batteries were sunken cost. But now Electricity costs have gone up - and I now had some disposable cash to be able to buy panels. 

I have now installed 9 x 545w JA Solar panels.

5 panels on the NE-facing Roof. 1 panel is shaded for part of the morning. Zone B

4 Panels on the NW facing Roof.  Zone A

Yes - it helps - but I'm not getting what I expected. My limited research tells me it may be because too few panels on a string. I did the panel calculator based upon inverter and panels - and it tells me a minimum of 3 panels to get to the 150W needed. Maximum is 9 panels per string. 

Need your advice on how I should install more panels.  I have an area above the garage that could take 4 more panels. But - it is South sloping by 5 degrees - so would put brackets to lift the panels up to 20 degrees to match the existing panels. 

 Do I add the 4 panels to Zone A - so MMPT2 has 2x strings of 4 panels?  Or since in same orientation and angle - add them so that string has 8 panels on it? 

Looking at the specs - I believe that I could probably add Zone C to Zone A in Parallel - as each panel maxes out at 13A - inverter can handle 26A. Or should I rather push the Voltage higher with 8 panels in Series? Advice please.

I get 5-6 hours of generation a day in September. (making about 20kWh / day off Panels in A and B

Would really appreciate your input and advice. 

 

Pic of House from Google Earth. 

 

 

You are going to have a lot of issues with shading. Even if a small part of a single panel in a string is shaded, the output will drop dramatically.

The number of panels per MPPT should not make that much difference as long as the voltage on it is at or above the minimum for the MPPT to start. So 4 panels is more than enough to get you to 150V for your inverter. With your complicated shading issues I would actually recommend to have as few as possible panels per MPPT to minimize the damage shading can do.

If you combine A and C, you might make your shading problems worse.

Typically the cost of adding brackets to improve the angle is more expensive than simple adding one extra panel to make up for a bad angle. But every case is unique. You can use this calculator to see how angle and direction will influence your output:

https://pvwatts.nrel.gov/

Can you send us your PV production charts.

 

Edited October 29, 20241 yr by HendrikBigChief

Thanks Hendrik for the reply.

Is this what you are looking for? 

Section B on my roof is PV-1.

 

Kind Regards, 

 

B is 

As was said above, your big issue is not the number of panels, but the shading. Even if you need to shorten string B to 4 panels, or move it around, that will help. Give String B more sunlight especially in the morning, and mid-day. Similar with String A, try to keep it in the sun during noon and late afternoon.

If you want to add any panels, for example at C, they will be sub-optimal no matter what if you can't get rid of shading, and if they are pointing Southwards. You could do better by putting them on micro-inverters rather than by trying to connect it to existing strings.

 

6 hours ago, HendrikBigChief said:

You are going to have a lot of issues with shading. Even if a small part of a single panel in a string is shaded, the output will drop dramatically.

The number of panels per MPPT should not make that much difference as long as the voltage on it is at or above the minimum for the MPPT to start. So 4 panels is more than enough to get you to 150V for your inverter. With your complicated shading issues I would actually recommend to have as few as possible panels per MPPT to minimize the damage shading can do.

If you combine A and C, you might make your shading problems worse. 

https://pvwatts.nrel.gov/

Can you send us your PV production charts.

 

Because it is indicated that A and C will be in parallel it might be a good call than if they were in series due to those huge shade generators 😅

On 2024/10/28 at 10:20 PM, ErwinB said:

Looking at the specs - I believe that I could probably add Zone C to Zone A in Parallel - as each panel maxes out at 13A - inverter can handle 26A. Or should I rather push the Voltage higher with 8 panels in Series? Advice please.

 

A and C in parallel could work. Definitely not in series, that will make shading worse. You will have to experiment. It also looks like you could potentially add one extra panel to B at the north side. If B is getting heavy shading from just one panel it might be worthwhile disconnecting that panel or moving it to a spot where it is not shaded.
 

20 hours ago, ErwinB said:

Thanks Hendrik for the reply.

Is this what you are looking for? 

Section B on my roof is PV-1.

 

Kind Regards, 

 

B is 

The charts confirm you are easily hitting minimum voltages and that shading is your biggest issue.

Thank You to HendrikBigChief, and GreenFields. 

Looks like the path to better solar generation is a chainsaw and some "trimming".
Thanks again for the help.

Regards, 

  

10 hours ago, HendrikBigChief said:

The charts confirm you are easily hitting minimum voltages and that shading is your biggest issue.

Too few panels in series is the larger reason the voltages are on the low end... however

1 hour ago, ErwinB said:

Looks like the path to better solar generation is a chainsaw and some "trimming".

with partially shaded strings the Voltage will be better, but the current flow will still be limiting the power produced... if you look at the Voltage and Current graphs for PV1, which is a string of 9 X JA Solar 280W panels in series, this time of year they are in shade until around 09:00, but if you look at the Voltage, its pretty high from around sunrise, even though the panels are in shade...