MPPT Controllers
As I continue the learning curve, I'm finding the answers I get always lead to 2 more questions... funny how that is... I've been working backwards in developing my solar needs, going from panels t...
Forum Discussion
CA Traveler wrote:
What do over amped PWM controllers do? ie Instead of +25% oversized they are say -15% ? Zap = smoke?
They do the over-amps and get warmer and warmer until some component "fries". They get pretty warm at rated amps, but can handle that with good ventilation (same as MPPT there) per their manuals re installation.
Usual advice is to ensure staying under rated amps when your array might be over-performing such as in colder temps by leaving a margin compared with normal temps.
The percentages are confusing as often used.
Say the panel can do 20 amps max. The controller would be 20 x 1.25 by one rule. = 25 amps. That 5 amps over is 1/4 of the 20 but 1/5 of the 25. So the controller is 25% above panel, but the panel is 20% less than the controller.
This is where the other usual rule of 80% for electric loads gets mixed up in all this, where now you want the load to be 1/5 smaller than the supply. But you want the wires for that to be 1.25 more but the fuse for that wire to be under that so the wire is not the fuse. So what does that make the fuse size wrt the load? And so forth. Only the NEC knows for sure! :)
