Does solar panel efficiency really matter much?

[Silver_Is_Money]

I wasn't sure where to properly post this on the forum, but: If panel A is 19% efficient, and panel B is 15% efficient, and they both have STC ratings of 260 Watts, and they both have PTC ratings of 233 Watts, and if panel B costs far less than panel A, what incentives (other than space savings) are there to help one decide to go with panel A as opposed to settling upon panel B and saving money?

And as merely a passing sidelight comment to this query, it seems that monocrystalline panels in general have higher efficiency, but more often than not polycrystalline panels with equal STC Watt output have a bit better PTC Watt output.

[russ]

Size as you noted.

[J.P.M.]

I wasn't sure where to properly post this on the forum, but: If panel A is 19% efficient, and panel B is 15% efficient, and they both have STC ratings of 260 Watts, and they both have PTC ratings of 233 Watts, and if panel B costs far less than panel A, what incentives (other than space savings) are there to help one decide to go with panel A as opposed to settling upon panel B and saving money?

And as merely a passing sidelight comment to this query, it seems that monocrystalline panels in general have higher efficiency, but more often than not polycrystalline panels with equal STC Watt output have a bit better PTC Watt output.

All other things being equal, panel B will likely be more cost effective but will have a larger footprint.

If you're space limited, reduce your use and thus reduce the required system electrical (and physical) size, then consider going with the more cost effective panel B and really save money.

While that's a big part of the story, there are other considerations. However, those other considerations are often magnified out of proportion to their real-life importance by those who want to profit from consumer's solar ignorance. Caveat Emptor.

For the most part, equal electrical sized systems in the same location, orientation and service initially produce about equal annual output. Some panels MAY be worth a SLIGHT up front premium for a lower annual output degradation rate, but probably no more than about 5% or so when considered over 25 yrs., and less for shorter time spans.

Claims of superior warranties may be valid, but are perhaps a bit overstated (REALLY read the fine print), and IMO, and in most cases, overkill. Usually and most often, things fail quickly or not at all, making 25 yr. warranty vs. 10 yrs. or so irrelevant. Also, I'd bet in 10 yrs. a lot of today's whiz-bang stuff will be in dinosaur mode like a Commodore 64 computer, replaced by better, cheaper, faster and more cost effective stuff.

[Sunking]

Efficiency only deals with the physical size of the panels. A 20% 200 wat panel will be 1 square meter. A 10% 200 watt panel will be 2 square meters. It al revolves 1 square meter. A 1 square meter 100% efficient panel would be 1000 watts.

[ZoNiE]

Efficiency only deals with the physical size of the panels. A 20% 200 wat panel will be 1 square meter. A 10% 200 watt panel will be 2 square meters. It al revolves 1 square meter. A 1 square meter 100% efficient panel would be 1000 watts.

Thank you for this. Answered a question that I have been pondering: What is the datum for the efficiency rating. Makes perfect sense now.

[Naptown]

All other things being equal, panel B will likely be more cost effective but will have a larger footprint.

If you're space limited, reduce your use and thus reduce the required system electrical (and physical) size, then consider going with the more cost effective panel B and really save money.

While that's a big part of the story, there are other considerations. However, those other considerations are often magnified out of proportion to their real-life importance by those who want to profit from consumer's solar ignorance. Caveat Emptor.

For the most part, equal electrical sized systems in the same location, orientation and service initially produce about equal annual output. Some panels MAY be worth a SLIGHT up front premium for a lower annual output degradation rate, but probably no more than about 5% or so when considered over 25 yrs., and less for shorter time spans.

Claims of superior warranties may be valid, but are perhaps a bit overstated (REALLY read the fine print), and IMO, and in most cases, overkill. Usually and most often, things fail quickly or not at all, making 25 yr. warranty vs. 10 yrs. or so irrelevant. Also, I'd bet in 10 yrs. a lot of today's whiz-bang stuff will be in dinosaur mode like a Commodore 64 computer, replaced by better, cheaper, faster and more cost effective stuff.

Says the man who bought the most efficient panels on the planet at the time.
But his assessment is correct.
Lower degradation over time may lead to overall production gains during the time allotted.
The choice is one of environment, temperature coefficients , and finally what the system will produce over it's expected life vs the initial cost to install
All depends on wether you want a Toyota or a Ferrari
In the long Run the Toyota will
Probably be a Better investment

[navajosolarguy]

Thank you for this. Answered a question that I have been pondering: What is the datum for the efficiency rating. Makes perfect sense now.

Not true. A high efficiency panel will produce more electricity than a std efficiency panel. Usually the same size or smaller..

[J.P.M.]

Not true. A high efficiency panel will produce more electricity than a std efficiency panel. Usually the same size or smaller..

You're not true in not correct. More output /area, not necessarily more output per nameplate Watt. Perhaps S.P. might be necessary if roof or ground space is small or if you place a high value on your roof real estate. Better yet, reduce your elec. load to reduce required system size and then use less expensive panels that fit the smaller space.

Systems of the same nameplate Wattage will produce nearly identical annual output in the same orientation, location and duty. S.P.'s lower annual degradation rate might allow a 5% up front premium over 25 years, less for shorter time frame.

The latest version PVWatts estimates S.P."premium" panels will produce a bit more than about 2%/year over non S.P. stuff in terms of annual output, and most of that seems due to the lower S.P. temp. coeff. See the latest PVWatts version as of 09/08/2012. The new PVWatts seems to agree with SAM and stuff I've written as well. In Fact, FWIW, SAM annual output/nameplate Watt for the LG 300 exceeds that of the S.P. 327 in Zip 92026 by a few %. I suspect colder climates may not fare quite so well, but close.

Further, check PVoutput.org for geographically similar systems of just about any size and mfr. You'll find very similar daily output per installed kW for most geographically close systems of similar orientation, S.P. or other mfr., no matter. It would take more collusion than I'm willing to accept as possible for that to happen as much as is reported.

Paying 15-25% more $$'s for what is essentially equal annual output doesn't seem cost effective to me. S.P's great stuff, but from a cost or LCOE standpoint, other quality equipment is more cost effective. Also, IMO, the S.P. warranty, while good, is overkill and still not bulletproof or worth that much of a premium. Read it carefully. Besides, if the stuff is that good, why is such a great (?) warranty needed in the first place ?

It's a free country. Just walk in with your eyes and mind open and be aware that with S.P. stuff, while good, you're paying a premium. It's similar to buying a Mercedes to haul groceries and paying for bragging rights when a Ford or Toyota is equal to the task.

Solar electricity, like your HVAC equipment or water heater is an appliance and a commodity, not a lifestyle.

[russ]

Not true. A high efficiency panel will produce more electricity than a std efficiency panel. Usually the same size or smaller..

A lot better to use numbers rather than standard and high which are only confusing terms. SP may well claim a 19% efficient panel is standard.

[englert123]

The efficiency of the solar panel is depend on the type and design of the roof as if you are using the metal roof then you have many advantages. As metal roof is the perfect platform for photovoltaic solar collection systems.

Mod note - link removed - next time will lead to being banned.

---Mod note: He was warned already: http://www.solarpaneltalk.com/showth...l=1#post133940 He is now banned.

[Sunking]

The efficiency of the solar panel is depend on the type and design of the roof as if you are using the metal roof then you have many advantages. As metal roof is the perfect platform for photovoltaic solar collection systems.

Mod note - link removed - next time will lead to being banned.

Completely useless reply for a scum bag spammer.