Cheap China Solar Controller Failure
For a couple days been noticing higher than the 14.6 voltage,.....going to 15, and even 15.5,....I knew something was not right. The next day it was showing 16, then quickly went to 17+.......I quickl...
Forum Discussion
mena661 wrote:
I'd like to see BFL do his testing using a higher end MPPT controller (or controllers preferably) to see if there is any real world performance difference between those and the cheap one's. Everyone here is basing their MPPT performance conclusions on ONE controller. They may not all perform the same.
I doubt the more expensive controllers are any "better" but one big thing is the efficiency curve and where you are on it.
I am near to maxing my Eco-W for panel watts, which puts it at the low end of its efficiency curve. Somebody with a $600 controller but operating with fewer watts of array wrt the controller's rating would get "better" results by being in a "sweet spot" on the efficiency curve. Plus there is more than one efficiency curve! Array watts per controller rating, temperature, maybe others.
So you would have to set up the contest allowing for that kind of thing too.
It is simple. Panel voltage and watts go down with higher temps while Isc goes up. MPPT needs that voltage and watts to get amps out, while PWM uses the Isc amps which stay up. At some higher temp the MPPT amps from the 24v panel become less than the total Isc amps would be from two 12s at the same wattage, and that's what I have seen when and where. Somebody else somewhere else at some other time of year may not get the same thing happen. Can't help there!
