December 21, 20232 yr I've discovered that when the sun is really bright in the early morning, my panels perform much worse. Must have something to do with casting "hard shadows" on the panels. I live in Johannesburg and on Wed 20 Dec, 8am, was getting 2kw out of the panels. On Thur 21 Dec at 8am, getting 0.8kw. Anyone else experience this? I guess the mitigation is cutting some branches from the tree
December 21, 20232 yr 34 minutes ago, RichardZA said: I've discovered that when the sun is really bright in the early morning, my panels perform much worse. Must have something to do with casting "hard shadows" on the panels. I live in Johannesburg and on Wed 20 Dec, 8am, was getting 2kw out of the panels. On Thur 21 Dec at 8am, getting 0.8kw. Anyone else experience this? I guess the mitigation is cutting some branches from the tree The angle of the sun wouldn't have changed much between Wednesday and Thursday. So the shadows would also be in the same direction. My experience is opposite to yours. NB! I have half my panels facing East. Wednesday there was a lot of cloud and production was quite variable. At 8:00 I was getting about 700 watts. This morning it's very clear and by 8:00 I have 1.9 kW.
December 22, 20232 yr On 2023/12/21 at 8:10 AM, RichardZA said: I've discovered that when the sun is really bright in the early morning, my panels perform much worse. Must have something to do with casting "hard shadows" on the panels. I live in Johannesburg and on Wed 20 Dec, 8am, was getting 2kw out of the panels. On Thur 21 Dec at 8am, getting 0.8kw. Anyone else experience this? I guess the mitigation is cutting some branches from the tree I am not based in Johannesburg, cannot comment on what would be normal for your array size at that time of the morning. During overcast conditions nearly all of the solar irradiance is diffused and the irradiance is uniformly distributed in the sky. On a clear day all of the solar irradiance is in the form of direct irradiance (direct sunlight on the panels) If conditions are perfect (ito no to much cloud cover) the diffused irradiance can temporarily alleviate the impact of shadows on panels. Edited December 23, 20232 yr by I84RiS
December 22, 20232 yr Full sun in summer on the Highveld heats up the panels by a huge margin. Hot panels drop in efficiency.
December 22, 20232 yr On 2023/12/21 at 8:10 AM, RichardZA said: I've discovered that when the sun is really bright in the early morning, my panels perform much worse. Must have something to do with casting "hard shadows" on the panels. I live in Johannesburg and on Wed 20 Dec, 8am, was getting 2kw out of the panels. On Thur 21 Dec at 8am, getting 0.8kw. Anyone else experience this? I guess the mitigation is cutting some branches from the tree Thursday we had clear skies up to around 12h. On Wednesday you could get up to 3 times more say 15min apart. There were lots of clouds and many times did we experience cloud edge that produced very high spikes for less than a minute.
December 23, 20232 yr Author I'm still thinking that a very dark shadow cast by a chimney or tree branch cast cuts out my panels more than diffused light in overcast conditions, where you can't get a heavy, dark shadow. Or am I on completely the wrong track?
December 23, 20232 yr 1 hour ago, RichardZA said: I'm still thinking that a very dark shadow cast by a chimney or tree branch cast cuts out my panels more than diffused light in overcast conditions, where you can't get a heavy, dark shadow. Or am I on completely the wrong track? Diffused irradiance should lesson the impact of shadows on the panels, so in some conditions you should get higher yields compared to direct irradiance conditions.
December 23, 20232 yr On 2023/12/21 at 8:10 AM, RichardZA said: I've discovered that when the sun is really bright in the early morning, my panels perform much worse. Must have something to do with casting "hard shadows" on the panels. I live in Johannesburg and on Wed 20 Dec, 8am, was getting 2kw out of the panels. On Thur 21 Dec at 8am, getting 0.8kw. Anyone else experience this? I guess the mitigation is cutting some branches from the tree The inverter will only draw as much as the load + battery need. If your battery is 100% at 8am, then the 0.8kW is the load of the house. I've also noticed that sometimes when it's cloudy, the panels generate more electricity for bursts - not sure of the reason. This is JHB South, On Wed with clouds at ~8am there was 2.9kW peak, the next day, it was clear and steady ~2kW Edited December 23, 20232 yr by system32
December 23, 20232 yr 2 hours ago, RichardZA said: I'm still thinking that a very dark shadow cast by a chimney or tree branch cast cuts out my panels more than diffused light in overcast conditions, where you can't get a heavy, dark shadow. Or am I on completely the wrong track? Like @Bobster. mentioned these shadows will not make such a big difference on 2 days in succession. We know for sure the 2 days in question one had lots of cloud and the other not within the time frame mentioned. If the SOC of battery was the same and you know you had the same load then it seems clouds are the most likely cause. On the gragh of @system32 we can see the 2.8kW peak. If the reading was taken 5min earlier or later the value would have been about 1.25kW. This was the day with clouds. His output matches mine. Edited December 23, 20232 yr by Scorp007
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