Solar Panel Spec - Can Someone Please 'Splain?

[xzyHollyxyz]

I was looking again at the specs on my new flexible solar panel:

21.7 Open Circuit Voltage
6.10A Short Circuit Current
19.9% Cells Efficiency
5.70A Optimum Operating Current
17.7V Optimum Operating Voltage

Could someone please explain what the 19.9% Cells Efficiency means?

Thanks!

[Almot]

Solar bike or a tiny trike car have no other choice but flexible panel. Installing a rigid panel on it would be difficult and affect the aerodynamic properties. A flexible panel without glass also means 15 lbs weight savings, important thing for a bicycle.

[Heap64]

I came so close to using those for my solar project. I was concerned about heat build up and if I really wanted to glue or stick them directly down on my roof. But they sure look like they have potential. I saw an electric bike/car that is using the same type of panel on their roof for a small commuter vehicle.

[Almot]

Most panels have around 14% efficiency, so yours at 19.9% are 20/14=1.4 times smaller per same wattage. This is important if you roof area is not big enough for solar wattage that you want. If roof is big enough, then this is not important.

Efficiency drops by 1% a year for rigid panels. In flexible panels like yours I would expect it to drop faster, because there is no protective glass layer and clear plastic degrades sooner. So, in a few years the efficiency of this particular panel could match the efficiency of rigid panels, and then it will become lower. But again, if you have enough total wattage after this aging degradation, this doesn't matter. This has been said on this forum many times already: if you can get more solar wattage, - do it.

[westend]

That module ought to get your Grp 27 recharged in a day of full sun.

[xzyHollyxyz]

NinerBikes wrote:
You did buy it to charge your batteries, didn't you?

Yes, I got it to charge the trailer battery (single Group 27) and then on a long trip, I will carry a Group 24 in the bed of my truck for whatever...

I got the Renogy 100W flex panel ($199). I put the 2 long sides on a piece of small PVC as framing. It has not had any real world use yet.

[mrkoje]

Did you get the Go Power flex panels? If so please tell me how you like them - I am about to get those myself.

[NinerBikes]

It's a 12V system. What is important, for battery charging purposes, is how to get 14.8V to your battery out of your charge controller, and keeping it flowing the near maximum amount of amps it is capable of, near 6 amps is what it looks like, for as long as possible, until your battery reachs a full charge.

You did buy it to charge your batteries, didn't you?

[WyoTraveler]

mitch5252 wrote:
So, is 19.9% a good number?

There is a formula for that.

efficiency % equals power output divided by incident radiation flux times area of collector

If I recall 40% is common. Newer ones higher. Suspect soft type less efficient. JMHO

[time2roll]

Yes 19.9 is fine. Still the wattage rating is what it is.

If efficiency could move from 20% to 40% you would have double the output for the same size panel. So far that stuff is still just in the lab and not available.

[mdamerell]

Today's commercially available PV modules have efficiency ranging anywhere from 6 to 21%

So yes, 19% is pretty good

[pianotuna]

Hi Mitch,

Yes, it is a good number.

[xzyHollyxyz]

So, is 19.9% a good number?

[pianotuna]

Hi,

It means 19.9% of the light energy may, under ideal conditions, be converted to electricity. State of the art (which we can't afford) is about 27%. Older panels were often 13 to 14% efficient.

The number will drop over time with a 25 year working life for most panels.

[12thgenusa]

It means a one square meter panel will produce 199 watts of power. The higher the efficiency the smaller the panel for the same power output.