TomC4306
Solar Obsessive
Solar panels don't work particularly well in the shade...
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Proposal from solar vendor - 200% overpaneling?
- Thread starter plutoz
- Start date
TomC4306
Solar Obsessive
Dude, rumor and innuendo.
Do YOU personally KNOW anything that would be helpful to this conversation?
The sol Ark 12k can handle 13k of pv. It clips at 12k. I regularly produce 12k of pv with mine.You are correct, I went back and read his email (it was a few months ago) and he told me they are under warranty but he still has to pay a local company to go up on the roof to replace them each time they fail, at a rate of 1 or 2 per year. I had read somewhere else that they tend to start failing more often at the 10 year mark which is roughly the age of his system.
The second quote I received was for 22 x 460 (10.1kW) panels with a SolArk 12kW inverter which has a max PV input of 9kW so a slight (10%) overpaneling.
Couldn't you avoid those few panels facing a different direction limiting the output of the array by putting them on a separate string and combining them before they go to the inverter? My previous system had two strings of 9 panels each with a combiner box. Unfortunately the installers of that system put the combiner box on the roof and I periodically had to go replace fuses in the combiner box which was fun...
I get this but why not just up the size the inverter so I can use more of that power? It seems like trying to fill a rain barrel with a fire hose. Sure you'll fill the rain barrel but a lot of that water just ends up on the ground all around it... poor analogy perhaps but best I could come up with
DougfromdaUP
Solar Enthusiast
You've got to decide the relative value of components, based on your needs.get this but why not just up the size the inverter so I can use more of that power? It seems like trying to fill a rain barrel with a fire hose. Sure you'll fill the rain barrel but a lot of that water just ends up on the ground all around it... poor analogy perhaps but best I could come up with
I have two main goals: reliable backup power, and to lower my electric bill. My 9kW inverter (a sol-Ark 12k) is powered by a 10.1 kW pv array. In the summer I produce all the power I need, with 30kWh extra available most days. But now, I'm lucky to produce 3 or 4 kWh on these cloudy, cold days.
Adding panels would give me more power to use in the winter, when I need it, at a relatively modest spending level. Adding another inverter to use the extra power after I charge my battery in July would be almost senseless.
I'd recommend looking at modeling like PVWatts, or some of the others, to learn what amount of power an array really produces throughout the year, and trying to define your goals before you accept any bids.
You accuse the contractors of "overpaneling;" I accuse them of under-educating. You should discuss your needs with them and have them re-bid.
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OzSolar
Whatever you did, that's what you planned.
I'd be curious to see what sort annual kWH/KWp the contractors are modelings. ~1500 is an ideal site.
FilterGuy
Solar Engineering Consultant - EG4 and Consumers
That is possible, but may be less than ideal. The strings that have full sun will pretty much be the only ones producing at any given time.
However, since the proposal is to use optimizers, it is kinda like having a separate controller at each panel... and that will maximize the output of each.
It is a cost tradeoff thing. Overpaneling allows better performance with clouds and in winter without the cost of a larger controller.
Mike 134
Solar Enthusiast
That is the beauty of the misinfonet. Anyone of any level of experience/information can put a posting online and the next reader thinks it has some level of accuracy.
"Better to be uninformed than to read the internet and be misinformed" Tom Jefferson, Mark Twain
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Mike 134
Solar Enthusiast
Is North in this picture straight up? So all those panels on the west side gable are +270 degrees?
pollenface
Solar Addict
Yes, I have noticed that.
I have at my disposal a 1140w array I can connect to an Epever 2210AN on a 12v system. The 2210AN has a max charging power of 260w @ 12v. I get home in a few days, if I get some extra motivation I might do some experimenting and see what happens.....
Not in these words, Epever state in the manual that over paneling greater than 1.5x could be a waste of PV & money even if safe Voc limits are maintained.
I think on a cloudy day, it would be priceless
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MajicDiver
Solar Enthusiast
1) size inverter for how much a/c you need and how much battery you need to charge. With some margin.
2) Add at least 2x panels over that for the following reasons:
A: remember in 20 years you will be at about 80%
B: Shading, cloudy days
C: Hot weather you will lose capacity- varies with panel manufacturer but all of then go down at temp goes up.
D. You will get dust, dirt, bird poop and everything else on them, heavy rain cleans good but you will not want to clean them often manually.
E. Your angle will never be correct, even if you adjust a couple times per year.
F. If you actually have more than you need you can disconnect one or more if one fails and have no problems. In a few years it could be hard to find a good match for a failed panel and it’s a lot cheaper usually to purchase panels in bulk than one at a time.
IMO, panels are the cheapest part of the system, don’t undersize the cheapest part.
MajicDiver
Solar Enthusiast
B
By the way, earlier in the year I had 6-8 turkeys that liked to walk all over one of my ground mount arrays- it’s 7 feet above ground on the low side
FilterGuy
Solar Engineering Consultant - EG4 and Consumers
Most charge controllers have a limit on how much they can be over-paneled. The limit is usually stated as "Max PV wattage" or "Max Isc" for the array. The limit is often a LOT less than 200% so check very closely.
MajicDiver
Solar Enthusiast
Mine allow 2x rated power, many do. I would not buy one that didn’t
FilterGuy
Solar Engineering Consultant - EG4 and Consumers
What kind do you have?
MajicDiver
Solar Enthusiast
Two Growatt MIN-TL-XH-US
OzSolar
Whatever you did, that's what you planned.
That's a rather silly statement
MajicDiver
Solar Enthusiast
Whatever you say
OzSolar
Whatever you did, that's what you planned.
Feel free to take this time to educate rather than make generic statements that are meant to be abrasive. EG: share the specs of at least 3 charge controllers that state they are happy about being 200% over paneled. Oh.. and show us your calculations. I'll be right here waiting.
Hedges
I See Electromagnetic Fields!
- Joined
- Mar 28, 2020
- Messages
- 21,272
Solar Edge - an installer's blog
Came across the following blog. It includes the company's installed system numbers and failure rates for SolarEdge, Fronius, Enphase. Also, information on limitations and best use of optimizers. https://www.mcelectrical.com.au/solaredge-inverter-optimiser-review/
diysolarforum.com
Some people have said a newer model was more reliable. But another named same model as having a high failure rate.
MajicDiver
Solar Enthusiast
I gave you the model numbers for the ones I’m using, you can download the spec sheets yourself. Why don’t YOU explain why you think the statement is silly?Feel free to take this time to educate rather than make generic statements that are meant to be abrasive. EG: share the specs of at least 3 charge controllers that state they are happy about being 200% over paneled. Oh.. and show us your calculations. I'll be right here waiting.
