MPPT Vs. PWM Cost Comparison -- Am I doing this right??

[jimindenver]

Bob,you might be right if someone was using 33 volt panels.However in the real world most off grid applications are with 12 volt panels.I think I've beat this dead horse enough.

RV systems are 12v, anything bigger and most off grid systems are 24 or 48v. 12v panels have been more popular due to the ease of use with 12v and availability but with the prices of GT panels dropping and MPPT controller options opening up, the big panels are getting more popular.

 

[akrvbob]

All solar panels are a nominal 12, 24 or 36 volt which means it's in name only, they aren't actually 12 volt. 12 volt panels are usually around 18 volt.

With a PWM controller all the power the panel produces above around 14 volts is lost forever. Most panels are around 18 volts so you lose a minimum of 4 volts or about 25% of the panels total production.

With higher voltage panels the percentage of loss goes up, but even 12 volt panels lose a minimum of 25%
Bob