System size confusion

[ButchDeal]

Ref:Butchdeal
My decision to go with LG 365 was two fold.
1. They are the neon 2 panels
2. Limited roof space

so I need to get the max output from the least number of panels.
size wise from specs I was given are the same so why not go with get 365w instead of 280w or 300w in the same space.
i just signed the contract for site inspection and have asked to max out the roof space with whatever can fit, which as per calculation is max of 21 panels. Which is very close to my 100% electricity usage.
site inspection will be the final decision as to how many can fit on the roof.

efficiency basically comes down to the ratio of watts to size. The lg 365 is the older version In 72 cell.

365w 72 cell is 18.6%. Neon 2
400w 72 cell is 19.3% neon 2
360w 60 cell is 20.8%. Neon R
335w 60 cell is 19.6% neon 2

note that the cells are the same size so the 72 cells are proportionally larger. So you will be able to fit more watts using the 60 cell version.

http://www.lg.com/us/business/solar-panel/products

http://www.lg.com/us/lgcombiz4/compa...l/all-products

[mbster]

I have read good things about SolarWorld panels, but I would be concerned that the warranty on my system depends on a company whose German parent has declared insolvency and whose US division is on the verge of bankruptcy.

Not sure if this would alleviate your concerns regarding SolarWorld, but I have heard that SolarWorld USA is close to procuring insurance backing on their warranties so that if they're gone, the warranty would still be good.

[brucet9]

[QUOTE=mbster;n351918]

[brucet9]

EWP, as you do your due diligence studying, pay attention to the spec sheet for temperature coefficient Pmax. Every panel manufacturer rates output at STC, which is a laboratory test by a brief flash of light under controlled temperature. Under real world conditions, the panels will be generating current and heat, running about 36 degF hotter than ambient air temp. Temperature coefficient Pmax tells you what percent of power output the panel loses per degree above 25 degC. Panasonic HIT high-end panels drop production only 0.258%/degC, SunPower high-end panels drop 0.38%/degC and Canadian Solar panels drop 0.41%/degC; some panels do much worse. In Florida, your panels are likely to be running at 32 degC above STC when ambient temp is 100degF, so you will be running 13% under specification; your 295s will become 256W panels.

A quick way to compare temperature performance of panels is to use PTC ratings (tested under operating conditions at 68degF ambient) instead of STC, but you still have to factor in LID

Now subtract another 2.5% of power due to permanent light induced degradation (LID) that occurs during the first several days of use, and your Canadian panels are down to about 250W on a hot day. Check specs of the other panels under consideration to see how they stack up.

BTW, annual permanent degradation of industry-best Panasonic HIT and SunPower E-series panels run 0.26% and 0.25% respectively, with less than 0.5% LID, so those panels maintain more than 90% of output at 25 years, but they are more expensive.

[sensij]

EWP, as you do your due diligence studying, pay attention to the spec sheet for temperature coefficient Pmax. Every panel manufacturer rates output at STC, which is a laboratory test by a brief flash of light under controlled temperature. Under real world conditions, the panels will be generating current and heat, running about 36 degF hotter than ambient air temp. Temperature coefficient Pmax tells you what percent of power output the panel loses per degree above 25 degC. Panasonic HIT high-end panels drop production only 0.258%/degC, SunPower high-end panels drop 0.38%/degC and Canadian Solar panels drop 0.41%/degC; some panels do much worse. In Florida, your panels are likely to be running at 32 degC above STC when ambient temp is 100degF, so you will be running 13% under specification; your 295s will become 256W panels.

A quick way to compare temperature performance of panels is to use PTC ratings (tested under operating conditions at 68degF ambient) instead of STC, but you still have to factor in LID

Now subtract another 2.5% of power due to permanent light induced degradation (LID) that occurs during the first several days of use, and your Canadian panels are down to about 250W on a hot day. Check specs of the other panels under consideration to see how they stack up.

BTW, annual permanent degradation of industry-best Panasonic HIT and SunPower E-series panels run 0.26% and 0.25% respectively, with less than 0.5% LID, so those panels maintain more than 90% of output at 25 years, but they are more expensive.

The difference between PTC and STC power for the panasonic modules is 94.3%. For recent Canadian Solar panels, it is about 91.3%. Are you suggesting that the extra 3% that the panasonic modules might produce relative to their STC rating is worth the (substantial) premium you'd pay for them? Personally, I'd just buy an extra Canadian Solar panel and still come out ahead.

Where efficiency matters is in space limited applications. When the roof size is limiting the size of the array, and even fully populated,100% energy offset can not be reached, the more expensive panels can start to make sense.

[brucet9]

The difference between PTC and STC power for the panasonic modules is 94.3%. For recent Canadian Solar panels, it is about 91.3%. Are you suggesting that the extra 3% that the panasonic modules might produce relative to their STC rating is worth the (substantial) premium you'd pay for them? Personally, I'd just buy an extra Canadian Solar panel and still come out ahead.

Nope. Not advocating, just posting information to show how close Canadian panels are to the industry top performers.

[mbster]

Not sure if this would alleviate your concerns regarding SolarWorld, but I have heard that SolarWorld USA is close to procuring insurance backing on their warranties so that if they're gone, the warranty would still be good.

They've just announced the policy! See http://www.solarworld-usa.com/produc...rance-program/

[Six4KilowWatt]

The cheaper system is better...That's a lot of money more for so few watts.