In series vs Parallel?

[rgleason]

Originally Posted by john61ct

To best handle partial shading, get a second 75/15 and go 1:1.

Originally Posted by rgleason

Agreed, for higher shaded efficienies, also consider Gensun mppt's too. If panel is too small with fewer cells use the booster version.

This may be a mis- post.

[noelex 77]

Originally Posted by mat jam

My so called inefficient PWM is via a company that has been in the industry for about 30 years and has an efficiency of 98.5% but the argument appears to be I have used an inefficient system.

The increase in potential production switching from a PWM controller to MPPT controller is not great (providing the panels are appropriate), but you are confusing controller efficiency with the more important system efficiency. Your PWM controller may be 98.5% efficient, but it is not 98.5% efficient in converting the available power from your solar panels into power that the battery can use. A typical MPPT controller will be less efficient, but the total system efficiency is higher.

Perhaps an analogy may help. Your car engine alone is more efficient than the engine plus the gearbox. The gearbox has some power loss. Nevertheless, the gearbox improves the overall efficiency (assuming ICE). Your car would have poor performance without the gearbox.

The voltage conversion inherent in MPPT works in many ways like a gearbox. It allows the solar panel voltage to appropriate, and different to the battery voltage. In the same way the cars gearbox allows the engine revolutions to be appropriate and different to the drive shaft revolutions.

Originally Posted by mat jam

Again I remind you that my Pwm can do in series. How is that possible when everyone states the Pwm's can not do in series.

Matt, you cannot connect your two “12v” panels in series with your PWM controller and a 12v battery without very poor efficiency. The output of the two panels would be not much more than would be obtained with a single panel. Parallel connection of your solar panels is the only practical option.

This does not mean your PWM controller cannot be used with series connection. If you had the same solar panels and a 24v battery system you would have to connect two panels in series, parallel connection would not work. PWM controllers do not have any voltage conversion so the arrays voltage has to be appropriate for the battery voltage.