clayswen
New Member
Is there a good rule of thumb on overpaneling? Maybe by 10% or 20%? I won't have a battery right now and I'll be grid tied and net metering. What does the inverter do with anything over the max wattage per mppt?
Overpanel
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MisterSandals
Participation Medalist
The SCC pulls the current it can use, up to the max that the array can supply.
What SCC and array are you considering?
Consider plugging a 2W nightlight into a 15A receptacle. What does the nightlight do with anything over the max that the receptacle can supply? Nothing, it pulls what it can use (2W).
clayswen
New Member
How close to the advertised wattage do you get out of your solar array on a good day (sunny all day)? If you have a 9kw solar array does it ever put out that amount or are the panels overstated? I know temp has alot to do with panel peak performance.
I'm thinking about under paneling going forward. The idea is to maximize the panels and not the SCC. SCCs are cheap enough now I can worry about available panel area and get maximum from the panels.
I use to think over paneling was a good idea, now I have second thoughts....lol
I use to think over paneling was a good idea, now I have second thoughts....lol
hwy17
Anti-Solar Enthusiast
Overpaneling makes less sense when you're exporting, because the lost production is lost export credits. Up to 1.2 doesn't lose much, beyond that you'd be better of looking at getting more inverter.
For off grid and zero export systems, overpaneling makes a lot of sense, cause at a certain point you're just trying to drag up poor days production good days are going to waste either way.
For off grid and zero export systems, overpaneling makes a lot of sense, cause at a certain point you're just trying to drag up poor days production good days are going to waste either way.
clayswen
New Member
That makes sense. I will leave it at 9.2kw array since it is 9kw max output. I do have another grid tie inverter that I can AC couple when I do the other array.
timselectric
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The most that I have overpaneled is 400%.
It was a bit wasteful. lol
It was a bit wasteful. lol
clayswen
New Member
Wow. Sounds impressive though.
timselectric
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I hit peak production soon after sunrise. And kept it at peak until sunset.
But there was a large hump of production in the middle that was clipped.
It was the most I could get from a single MPPT each day. But a lot of wasted potential production in the middle of the day.
Winter was the same as summer. lol
JWLV
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Hehe I bet you were having a good time when it rained for 2 weeks straight!
timselectric
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Didn't phase it at all. lol
JWLV
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Solar panels have gotten so cheap that you can overpanel as much as you have physical space for it. I've only used about 1/10 of my backyard so far with my 6kw array. So I could actually go as much as a 60kw array
With that I can make my own supercharger at home for my Tesla.
Thats the thing though, if your trying to capture more on poor days, how does over paneling really help? Trying to wrap my head around it.
Example;
If we have 1200w of panel and 1000w of SCC we are over paneled but the SCC will see more time at max power and be better utilized.
If we have 1200w of panel and 1500w of SCC capacity, we are not getting the most use of the SCC but we will never loose the extra 200w of solar panel capacity.
In low light, as long as your string is setup correctly, how does over paneling help the panels capture more in low light? Is this an issue with large MPPT and voltage range? Is this an SCC capability issue?
My strings start pulling in at about 1-2w and climb from there. I have both over and under paneled. Doesn't seem to make much difference on the lower end.
What am I missing here?
clayswen
New Member
I know this. The more I read the more I look in the mirror and look like Forrest Gump….”I am not a smart man Jenny”
timselectric
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In low light conditions, panels may only produce 50% of the rated output. Twice as many panels will double the production in low light conditions.
Exactly
So if I double my number of panels but I am not maxing out my SCC, I get the best of both worlds? Max at low light and max at high light?
So if I understand it correctly, we really just need to add more SCC? SCCs are cheap enough, why not?
hwy17
Anti-Solar Enthusiast
Nothing wrong with doing so.
In systems where that would mean crossing over the 100, 200, 300, amp threshold it might be easier to not have to be prepared for the higher amperage though.
Add that with the expectation that the extra power won't be used, and then the result can be prefer not to have that much SCC.
timselectric
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That's not overpaneling.
Better option, if you can.
Overpaneling is a great option if you have enough production on sunny days. But not enough in low light conditions.
But if you need more production all of the time. You need more SCC's.
MisterSandals
Participation Medalist
Using SCCs implies having batteries and batteries have max charging rates. So that is one "why not?"; there is a limit to just adding more.
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