What module parameter indicates its low light efficiency?
I don’t think that there is anything on a module data sheet that specifies this as far as I know.
I think the only way to know is from the technology being used. It’s a good question @BrownBird, I hope someone else has more info.
Low light efficiency seems to be more of a marketing term. The amount of energy produced by a solar panel is directly proportional to the amount of solar irradiance measured in W/m2 (sunlight). I don’t know of any actual physics or properties of a solar cell which would make them more efficient under low light conditions.
Lower light W/m2 = lower power ouput. It’s very linear for all solar cells.
Thanks for the graph design it make us more clearer
Lower ling W/m2
Interesting graph, it seems 37-39 volts achieves optimum power output.
Did a bit more research on academic sites. It comes down to the PV module components, “The low light behaviour of a solar panel is mainly dependent on the shunt resistance and series resistance of the cells”. All of which seems to relate to quality & cost of circuits, resistors, individual cell material used in a PV module and consistency/quality of material used by manufacturer. Apparently standardised testing is conducted in laboratories with software analysis of PV Module performance.
Thus it seems, cheap PV modules are unlikely to be low light power producers, mid range ones are anyones guess and expensive ones might produce 10% more power over their life. Based in techniques and materials used today to manufacture PV modules.
I thought some thin film modules used to perform better in low light (shaded) conditions, compared to mono silicon?
Yes @Marty, I think the now mostly obsolete thin-film modules performed quite well in low light conditions but since their overall efficiency was very low (approx 10 to 12%) then they still didn’t come close monocrystalline modules with efficiencies of 15 to 17% at the time.
From what I know the main reason they were popular back in 2010 and earlier was due to the low price compared to monocrystalline panels.
@BrownBird, Interesting insight but considering almost all the major manufactures now use the same mono PERC P-type cells in a half-cut configuration there is really minimal difference - I would say 1-2% at most. I have 8 different panels with module-level Tigo optimisers and monitoring and I can see virtually no difference between the same size panels under cloudy conditions.
The thickness of solar cells is less than four strands of human hair. Since each cell is small, it can only typically create 1 or 2 watts of energy. They are linked together like chains to make large blocks called panels or modules so that the power output can be boosted.
The amount of sunlight the panel gets and the location are the power output determiners.
If there’s a shade such as clouds or anything that covers a portion of the whole module, it can lessen the generated power of the panels. Since there is a change in the sun’s position, there’s also less output during the summer and spring compared to fall and winter.