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Weird dip/spike in generation in good sunshine
Hi all,
This is my first post and visit. I wasn’t quite sure how to word this (or what to search for from other posts). Hopefully this makes sense and I can tap into your collective wisdom :-).
I’ve had a PV system for nearly a year now and I’ve noticed a weird pattern on days of good constant sunshine.
There is a smooth ramp up of generation from sunrise till about 10:30 am when there is a dip of about 30%. It then remains constant at that level until the sun moves into shade. Up till then, there is no shadow on the panels.
The panels are facing 130 degrees, south east, so catch the early morning sun. The roof is 38 degrees. At my latitude at 10:30am today, the sun is at 140 degrees and 24.5 degrees altitude. (though I notice the same behaviour throughout the year).
On a second string, the opposite behaviour happens, fairly constant/level generation until it takes a sudden jump up by about 50% at about 14:30, then gradually reduces as the sun sets.
Do you know what creates that behaviour?
Hope you can help me.
Many thanks!
Richard
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2 Replies
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So I had the chance to speak to the company that installed my system. They said that because the inverter is 3.6Kw, that what’s happening is that the generation is being limited by the inverter.
Why it allows the generation to go over the limit for so long is a bit of a mystery (it’s over 3.6kw for nearly an hour). Indeed, if I look back through the data, there are many occasions where generation goes over 3.6kw temporarily. So I’m wondering is there a tolerance that kicks in after maybe 45 minutes or something so it allows bursts of over 3.6kw but not sustained?
So I guess the new question this raises for me – if the panels are generating well over 3.6kw on a good day (I’ve seen bursts of over 6.5kw), and the inverter is restricting it to 3.6kw, where does the excess power go?? It’s basically being wasted I guess?
Is it possible to get an inverter at a higher capacity? I guess that requires a different grid connection and probably a larger battery too, as perhaps the grid wouldn’t let me send back more than 3.6kw?
Thanks!
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Hi Richard,
It’s a good question, hopefully someone with better knowledge than me can answer you mate!
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