What you can do about clouds slashing your solar power

Hanno Labuschagne

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What you can do about clouds slashing your solar power

Research shows that a small amount of cloud cover can have a dramatic impact on the amount of power a solar panel produces. Solar Advice director Neil Berrow says there are ways to compensate for South Africa’s cloudy days.

According to research published in Sustainability, solar panels that are 25% shaded produce 33.7% less power, while those shaded 75% produce 96.2% less power.

MyBroadband approached Neil Berrow of Solar Advice, who proposed solutions to mitigate the impact of weather instability on solar power generation.
 
Just remember that clouds can also dramatically spike the intensity of the the photon stream hitting the panels, causing a surge in energy production, sometimes for just a few seconds.

I've occasionally seen the cloud edge effect (as it's called) cause nearly a 40% surge on my 9-year-old solar PV system.
 
Just remember that clouds can also dramatically spike the intensity of the the photon stream hitting the panels, causing a surge in energy production, sometimes for just a few seconds.

I've occasionally seen the cloud edge effect (as it's called) cause nearly a 40% surge on my 9-year-old solar PV system.
True, and this is exactly what the article should be addressing: The risk of maximising (over speccing) your array to the extent that it blows the MPPT controllers due to excessively high voltage. An expensive mistake and one that takes very careful planning to avoid.
 
True, and this is exactly what the article should be addressing: The risk of maximising (over speccing) your array to the extent that it blows the MPPT controllers due to excessively high voltage. An expensive mistake and one that takes very careful planning to avoid.
I think the cloud edge effect increases the current and voltage is not affected so the mppt, at least in the sunsynk, should clip the amps during these events. Voltage is affected by temp and increases at lower temperatures.

Was cloudy today in Cape Town and seen mine go from 3kw to over 10kw in a matter of seconds.

Voltage vs current graphs from today. No spikes in voltage due to cloud edge but definitely spikes on the current. Still below the rating of the MPPT. Will see what cloudy summer days brings. Screenshot_20210919-200155_SOLARMAN%20Business.jpgScreenshot_20210919-200118_SOLARMAN%20Business.jpg
 
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True, and this is exactly what the article should be addressing: The risk of maximising (over speccing) your array to the extent that it blows the MPPT controllers due to excessively high voltage. An expensive mistake and one that takes very careful planning to avoid.

One of the reasons you build the array under the maximum Open Circuit voltage.
Thats the maximum voltage you'll get from a panel, even under cloud effect.

No careful planning needed, just basic math.
 
As for the article "What you can do about clouds slashing your solar power"

Simple, add more panels (and inverter(s) if needed).

Panels are still the cheapest part of the system. Batteries cost more. Ideally you'd have 3-4 days battery, but its more cost effective to just buy more generation.

In a couple of years that will change (assuming the rand doesn't repeatedly devalue), but currently (haha), it makes more sense to supplement generation vs storage.

Its what I have done anyway. I have roughly 13KW of panels now, which is far more than I will need, even in the depths of winter, and 1-2 hours of nominal generation a day.
 
As for the article "What you can do about clouds slashing your solar power"

Simple, add more panels (and inverter(s) if needed).

Panels are still the cheapest part of the system. Batteries cost more. Ideally you'd have 3-4 days battery, but its more cost effective to just buy more generation.

In a couple of years that will change (assuming the rand doesn't repeatedly devalue), but currently (haha), it makes more sense to supplement generation vs storage.

Its what I have done anyway. I have roughly 13KW of panels now, which is far more than I will need, even in the depths of winter, and 1-2 hours of nominal generation a day.
You have 13kWp? Wow. What is your MPPT controller rated at?
 
You have 13kWp? Wow. What is your MPPT controller rated at?
I have the 8.8Kw Sunsync w/9.5KW of panels + 3KW Victron Multisync with 3.3KWish of panels.
The Victron has the Sunsync as (fake) "grid" backup.

2 different houses (same plot).

Still have room to double up on panels on both houses if needed in future.

If you look closely you'll see both houses (white roof on the larger one, with no windows at the moment!) almost top left.

1632081771405.jpg
 
I thought the obvious solution was to install a coal burning furnace at the back of the house.
 
Pffft amateurs. My cloud seeding canon and fan system takes care of this. Clouds dissipate in no time.
 
"Berrow’s solution is to enlarge the panel and battery system to produce extra energy stores that will cater to cloudy days with low production."

This guys a genius, why didn't i think of this!
I received the email from MyBroadband asking my opinion, I mentioned one obvious way to tackle this, there was a quite a bit more that I said too which wasn’t added. I also said that I would be interested in hearing other potential ways of handling this.

Bit more context for you.
 
I received the email from MyBroadband asking my opinion, I mentioned one obvious way to tackle this, there was a quite a bit more that I said too which wasn’t added. I also said that I would be interested in hearing other potential ways of handling this.

Bit more context for you.
No worries man, I was only joking, hence the italics.

Very nice website by the way. :thumbsup:
 
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Just remember that clouds can also dramatically spike the intensity of the the photon stream hitting the panels, causing a surge in energy production, sometimes for just a few seconds.

I've occasionally seen the cloud edge effect (as it's called) cause nearly a 40% surge on my 9-year-old solar PV system.
Ja. People think knife-edge diffraction and Fresnel zone theory only apply to radio waves. Meanwhile, it is a phenomenon of the total electromagnetic spectrum.
 
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