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Good day all,

Just need some advice on my solar setup which was installed recently in the Pietermaritzburg Kzn region.

I have 6 panels (415w each) mounted on my north side roof and 6 panels (415w each) on the westerly side closer to north.

Now the issue I found is that I am not receiving the total possible production from this setup. In fact the total I noticed was 3.5kw which is a good 1.5kw roughly shy.

Is this seasonal related because the sun is shining well these days however the angle of the sun has altered itself as oppose to summer?

If you guys have some recommendations let me know. 

Thanks

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Do you have a single or dual MPPT inverter and are the two series of panels arranged on separate MPPTs if it's a dual MPPT.
If it's a single MPPT and all the panels are connected to that single MPPT then you will have to live with the degraded solar performance. 

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Posted (edited)

Thanks guys. Will send the pics later when I'm up there.

Yes its dual Mppt inverter (sunsynk 8kw) with each set on each. The panels are arranged in series on each.

Edited by Inzaghi
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I checked May last year and my production looks the same as this year. It look like solar irradiation is lowest for pietermaritzburg around May.

By September it goes back up. The sun's angle is very low I would have to cut down the forest around my house to gain very little. In summer I get good production from 7 am whereas now the sun hits the panels after 9.

 

Screenshot_20220506-151256_ShinePhone.jpg

Screenshot_20220506-151328_ShinePhone.jpg

Screenshot_20220506-151352_ShinePhone.jpg

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41 minutes ago, Buyeye said:

I checked May last year and my production looks the same as this year. It look like solar irradiation is lowest for pietermaritzburg around May.

By September it goes back up. The sun's angle is very low I would have to cut down the forest around my house to gain very little. In summer I get good production from 7 am whereas now the sun hits the panels after 9.

 

Screenshot_20220506-151256_ShinePhone.jpg

Screenshot_20220506-151328_ShinePhone.jpg

Screenshot_20220506-151352_ShinePhone.jpg

Thanks for this info.

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Posted (edited)

I'm in PMB midlands area, and yes, as @Buyeye says the sun is low, and not a good month for solar. The pitch of your roof looks like 19 to 25 Deg, and as we move to winter, that angle is not optimal. The easiest way to increase solar generation is to install more panels for the "bad" months and rainy days. You're SunSynk 8.8 kW Inverter can Generate 10.4 kW from solar, but some have installed between 12 and 13 kWp of panels to help with the "bad" months and rainy days. 👍

I currently only have 6.6 kWp of panels, but here is the output for today.

I have two strings, one at 290deg W and the other at 25deg NE.

image.png.1860ec0481080850ee89be9b8b0915dd.png

 

Welcome to the forum, and may you enjoy your new power independence. :)

Edited by TimCam
Wrong graph
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5 minutes ago, TimCam said:

I'm in PMB midlands area, and yes, as @Buyeye says the sun is low, and not a good month for solar. The pitch of your roof looks like 19 to 25 Deg, and as we move to winter, that angle is not optimal. The easiest way to increase solar generation is to install more panels for the "bad" months and rainy days. You're SunSynk 8.8 kW Inverter can Generate 10.4 kW from solar, but some have installed between 12 and 13 kWp of panels to help with the "bad" months and rainy days. 👍

Welcome to the forum, and may you enjoy your new power independence. :)

So you saying I can overspec on panels to compensate for the lower efficiency in my case?

Its such a pleasure to have full time power in this city which is constantly plagued with outages.

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Posted (edited)

Yes, you can overspec the panels to a certain amount (Power and Current), but NEVER overspec on Voltage. Try and get your strings to 425V, but NEVER go over 500V, this will destroy the inverter. Always use VOC (Voltage Open Circuit) for this calculation.

 

Edited by TimCam
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12 minutes ago, Inzaghi said:

Its such a pleasure to have full time power in this city which is constantly plagued with outages.

Yip, as I type now we have a power failure. Load-shedding is only at 18H00, but we just carry on with batteries now. 😄

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44 minutes ago, TimCam said:

I'm in PMB midlands area, and yes, as @Buyeye says the sun is low, and not a good month for solar. The pitch of your roof looks like 19 to 25 Deg, and as we move to winter, that angle is not optimal. The easiest way to increase solar generation is to install more panels for the "bad" months and rainy days. You're SunSynk 8.8 kW Inverter can Generate 10.4 kW from solar, but some have installed between 12 and 13 kWp of panels to help with the "bad" months and rainy days. 👍

I currently only have 6.6 kWp of panels, but here is the output for today.

I have two strings, one at 290deg W and the other at 25deg NE.

image.png.1860ec0481080850ee89be9b8b0915dd.png

 

Welcome to the forum, and may you enjoy your new power independence. :)

Thanks. Now I don't feel so bad. Your maximum efficiency is close to mines as well.

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If it is only 1 or 2 panels with shading problems, wouldn't a "solar optimizer" work in your circumstance? 

How good are these optimizers, does anybody have any firsthand experience with it?

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On 2022/05/08 at 8:49 PM, Vaal said:

If it is only 1 or 2 panels with shading problems, wouldn't a "solar optimizer" work in your circumstance? 

How good are these optimizers, does anybody have any firsthand experience with it?

Never heard of a solar optimizer.

I'm planning on adding more panels to compensate for this low production in winter.

With regards to the sunsynk 8kw inverter, what happens when you exceed the Ac load? My installer never add my geyser (150l with 3kw element) to the inverter fearing that I may damage the inverter. How true is this? 

Also has anybody tried mounting those solar trackers (single or dual axis type) for better solar efficiency? I have some concrete roof which I think this may work well with. Any thoughts?

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16 hours ago, Inzaghi said:

Never heard of a solar optimizer.

I'm planning on adding more panels to compensate for this low production in winter.

With regards to the sunsynk 8kw inverter, what happens when you exceed the Ac load? My installer never add my geyser (150l with 3kw element) to the inverter fearing that I may damage the inverter. How true is this? 

Also has anybody tried mounting those solar trackers (single or dual axis type) for better solar efficiency? I have some concrete roof which I think this may work well with. Any thoughts?

It is not great to have a 3kw element on the inverter unless you have a big battery bank. The geyser is normally on the rest of the house non essentials circuits to at least power those loads from PV during the day.

I doubt that the geyser would damage the unit. I think the bypass current while the grid is on is something like 43A. A 150L geyser at 20 deg would need 7kwh to heat to 60 degrees. You would not want to do this during LS when no sun from batteries.

Trackers can add 25% to output but the enormous cost to have it professionally designed and approved is not worth it. More panels just much more cost effective.

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7 hours ago, Scorp007 said:

It is not great to have a 3kw element on the inverter unless you have a big battery bank. The geyser is normally on the rest of the house non essentials circuits to at least power those loads from PV during the day.

I doubt that the geyser would damage the unit. I think the bypass current while the grid is on is something like 43A. A 150L geyser at 20 deg would need 7kwh to heat to 60 degrees. You would not want to do this during LS when no sun from batteries.

Trackers can add 25% to output but the enormous cost to have it professionally designed and approved is not worth it. More panels just much more cost effective.

Thanks buddy,

I forgot to add one more thing. 

I'm in the process of adding more panels and need some info in terms of how this will impact mppt performance.

I currently have 6 panels on the north side (string 1 mppt 1) and 6 panels on on north west side (string 3 mppt 2). These are 415w panels. 

I managed to source 460w panels and plan to shift the current string 3 to string 2 so that the 415w panels are on the same mppt. Likewise the 460w will be split into 5s in string 3 and 4 each.

How will this impact the performace of mppt 1 that has string 1 and 2 facing different directions or is it not an issue? Similarly with string 3 and 4. 

 

Thanks

 

 

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44 minutes ago, Inzaghi said:

Thanks buddy,

I forgot to add one more thing. 

I'm in the process of adding more panels and need some info in terms of how this will impact mppt performance.

I currently have 6 panels on the north side (string 1 mppt 1) and 6 panels on on north west side (string 3 mppt 2). These are 415w panels. 

I managed to source 460w panels and plan to shift the current string 3 to string 2 so that the 415w panels are on the same mppt. Likewise the 460w will be split into 5s in string 3 and 4 each.

How will this impact the performace of mppt 1 that has string 1 and 2 facing different directions or is it not an issue? Similarly with string 3 and 4. 

 

Thanks

 

 

I am not sure which direction the 10 x new panels would face(string 3 and 4).  As string 1 on MPPT1 6 X 415w will face north and string 2 6 X 415W on MPPT1 facing west towards North will be summed the MPPT might have difficulty in getting the max power point when 1 is stronger than the other. Strings in parallel will cause the weaker string to pull the stronger string to it's voltage. The effect will be that the string 1 will be reduced a lot.

It is best to provide the Voc of the 415W and 460W panels as well as their Imp current. Rather indicate the size and direction for each of the strings 1 to 4. Strings 1 and 2 on MPPT1 and strings 3 and 4 on MPPT2.

Edited by Scorp007
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40 minutes ago, Scorp007 said:

I am not sure which direction the 10 x new panels would face(string 3 and 4).  As string 1 on MPPT1 6 X 415w will face north and string 2 6 X 415W on MPPT1 facing west towards North will be summed the MPPT might have difficulty in getting the max power point when 1 is stronger than the other. Strings in parallel will cause the weaker string to pull the stronger string to it's voltage. The effect will be that the string 1 will be reduced a lot.

It is best to provide the Voc of the 415W and 460W panels as well as their Imp current. Rather indicate the size and direction for each of the strings 1 to 4. Strings 1 and 2 on MPPT1 and strings 3 and 4 on MPPT2.

String 1 (north) 6x415w (Voc 47.8v Imp 10.56A)

String 2 (northerly Western direction) 6× 415 w (same as above)

String 3 (northerly Western direction) 5 x 460w (Voc 49.5v Imp 11.05A)

String 4 (Same as string 3). There is also an option for the panels on this string to fit a small section on the northern section towards east (nne 10 deg)

 

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If you can fit 12 panels on the northerly/Western direction then fit 6x410 on string 3. Fit 6x410 on string 4. Fit the new 460w panels as 5 on string 1 and 5 on string 2. It is never a good thing to have different size panels on the same MPPT. Better if each MPPT has different size panels. If you fitted 6x410 on string one you will loose the power of 1 of them due to the 5x460 in parallel having about a 40V lower voltage. 

If the northerly/Western can take only 10 panels then it becomes 5x410 in each of string 3 and 4. Again we will have the same panels in each of the 2 strings.

This is how I see it but let's see what other's suggest.

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On 2022/05/14 at 5:41 PM, Inzaghi said:

Never heard of a solar optimizer.

I'm planning on adding more panels to compensate for this low production in winter.

With regards to the sunsynk 8kw inverter, what happens when you exceed the Ac load? My installer never add my geyser (150l with 3kw element) to the inverter fearing that I may damage the inverter. How true is this? 

Also has anybody tried mounting those solar trackers (single or dual axis type) for better solar efficiency? I have some concrete roof which I think this may work well with. Any thoughts?

To the best of my knowledge, it wouldn't help a lot to add more panels to a string which have got shading problems because the shaded panels will pull the whole string down. 

Problem with trackers are that they are very wind sensitive  and expensive. If you have space rather spend money on extra panels rather than a tracking system. If possible you can manually adjust the tilt angle of the panels for better winter production. Have you played around a bit on this site? https://pvwatts.nrel.gov/pvwatts.php

The question is still, how many panel/s have shading problems?

How early in the morning are your batteries fully charged?

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6 hours ago, Vaal said:

To the best of my knowledge, it wouldn't help a lot to add more panels to a string which have got shading problems because the shaded panels will pull the whole string down. 

Problem with trackers are that they are very wind sensitive  and expensive. If you have space rather spend money on extra panels rather than a tracking system. If possible you can manually adjust the tilt angle of the panels for better winter production. Have you played around a bit on this site? https://pvwatts.nrel.gov/pvwatts.php

The question is still, how many panel/s have shading problems?

How early in the morning are your batteries fully charged?

4 panels in North have shade till about midday. The problem is my building is on a slope lower than my neighbors so the only option i have is to move them upwards which will solved it.

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