Solar Panel efficiency spec

[ffrree]

What does that mean ?
E.g. a Solar Panel rated at max. power output of 300W with a efficiency spec. of 20%, does it mean the maximum I can get out of it is 25% of 300W, which is really 60W ?

Or it really means, it can convert 20% of sun energy impacting on it, and can deliver to a maximum of 300W, so for that to happen, it needs 1500W of sun energy reaching it? Assume everything else being within spec. e.g. temperature etc.

 

[RCinFLA]

It is efficiency for full standard sun intensity of 1000 watts/m2 and temperature specified, usually either 25 degs C or 40 degs C.

20% is 200 watts output per square meter of PV panel area. A 300 watt panel will be 1.5 sq meters in area size.

Depending on ambient temp and sun intensity a panel may get up to or even above 60 degs C. This drops its efficiency.

 

[Mattb4]

It is important to understand this since there are many dodgy solar panels out there that makes claim to wattage they can not deliver. I see many 300w claimed panels for sale right now that are less than a meter squared in size. Simply not possible based on STC and efficiency.

A good write up about how panels are rated. https://solarmazd.com/stc-ptc-noct-what-do-they-mean-and-how-to-use-them/

 

[HRTKD]

Since this is a generic question not related to a specific vendor, I moved the thread to the "Solar Panels" subforum.

 

[jeff164]

i found this site to be quite useful. living in South East Asia on the 13th parallel north is typically very hard on PV panels.

Temperature and PV Performance Optimization | AE 868: Commercial Solar Electric Systems