B
billybee
so if its + or - 2% at 45'c should i expect to lose 10% thata 20x 0.53% ish over that temp range.
Today was a great day to see the temperature phenomenon.
It was about 20'C, no cooling benefit of any breeze and a mixture of sunny spells and cloud.
There were cloudy spells with generation being just a trickle, and when the sun came out power soared to 3.5kW. Then gradually the power output declined (as the panels got hotter) and settled around 3.0kW. Then a cloud would block the sun again, power would drop to 700W again, the panels cooled, the sun came out again and the power jumped back up to 3.5kW.
So I reckon that I was seeing a 15% loss of power output due to temperature.
The power-derating temperature coefficient of my panels is 0.43% per degree Celsius. So a rise of 35 degrees in panel temperature would explain the 15% drop in power output.
With ambient temperature around 20'C, the panels would appear to have been reaching 55'C after being in strong direct sun for many minutes.
well i agree there, the only other thing is on cold days i offtern get the same diffrence out of the last 21 days from 4 to 10kw production ive been out performed on 17 days by upto 23% but in saying that i have beaten him 4 times so even though were 10km apart weather could play some part may be cloudy here and raining there. thanks for the help anyway
the heat thing with what youve said above i can understand and agree with, cool down power up heat up power goes down and if that was happerning and mine was going up after some clould great, but mine never go back past the same output once it hits 2450 thats is best for that day (hot days) half an hour clould and it will drop but within minutes of clould clearing back to 2450 again and thats it.
or a dodgy panel?
to answer some questions
. but if its shading or faualty panels i would expect one string to be better than the other later in the day. after about 10am and for the times i get 2450 (hot days) both strings are on 8 amps and about 1200w. so if its a faulty panel there must be 2 one on each string.
thanks all
I've already explained in detail where your system is underperforming and what you can do about it.to answer some questions
roof pitch is ni on the same possibly a degree or two diffrent. according to what he told me we facing within a degree or two the same way. its not the drop thats my concirn its that it doesnt get high enough to drop (hot days) going of the inverter size and panel i'm loosing more like 20% of my peak and going of what the inverter and panels have peaked at could be over 25%. to get a drop you need a peak.
i do get a shadow i think early morning as the top string is always lower than the bottom for an hour or so. but if its shading or faualty panels i would expect one string to be better than the other later in the day. after about 10am and for the times i get 2450 (hot days) both strings are on 8 amps and about 1200w. so if its a faulty panel there must be 2 one on each string.
i know nothing about thermal camers, i'm changing the inverter next week and if that doesnt work will have to put a thermiter on the roof to check temps. sounds possibly heat is the problem. but its the way they react.
could we be looking at vaultage from the panels. mine is about 560v (inverter) and ive noticed a system with a sunnyboy inverter has much better outputs on hot days, sunny boys 700v also the eversolar i'm compairing with can run at 680v.
thanks all