Thoughts on B-grade panels?

[zzrider]

So I'm shopping for approx 5KW of PV for an off-grid home we're building, looking for panels in the 460-530w range. I found a local seller who has a variety of "B-grade" Heliene panels which he says are unused, straight from the factory but have cosmetic blemishes and no factory warranty.

He's local and I can pick them up myself which is appealing, and his price is very reasonable, but I'm leery of the no warranty. This is going to be our primary power source for this off-grid house.

Does anyone have any first-hand, long term experience with new Grade B modules? Are they reliable and do they actually produce to spec?

 

[PreppenWolf]

I'm not sure on the grading, but I have panels with broken glass I bought from a recycle plant that still produce 80-85% of rated output with no issues. Solar panels are pretty durable even after damage.

 

[Hedges]

What price per watt?

There are also used and new excess deals. The used in particular will be more like half the size you're considering, but that does make them easier to manhandle.

You want a brand known or durability.
If the price is right, warranty becomes even less important.

 

[SamDeleted]

Really depends on exactly how cheap the panels are

 

[Millennium]

Anyone living in hot climates, like Arizona, need to seriously consider the Power Temperature Coefficient of the panels they buy.
Most installers don't know this, but the really good panels will have a Temperature Coefficients of Power of -0.24.
A temp. coef. of Pwr of -0.29 is good and -0.34 is acceptable.

I've seen panels with a Temp Coef. of Pwr of -0.44, which is really poor.
During Arizona summers, these panels produce about 55% of the rated power and on 115-degree days they produce about 36% of their rated power.

 

[Solarcabin Channel]

Check around and contact panel dealers and ask for a bulk discount and you might find a better deal and have A grade panels with a warranty.

If you buy all your equipment from the same dealer they are usually happy to give you a discount

 

[KITROBASKIN]

How about asking to purchase one or a few units and test them yourself? Seems like their initial performance should reveal their future performance.