04-20-2018, 04:23 AM
The big seller of the MPPT controller is it's ability to convert excess voltage into amperage.
Oversimplification of best use case.
MPPT allows your panel array to run at a different voltage than your batteries.
- smaller combiner boxes -- or none at all
- surplus panels with "weird Voc" work great
- reduced power loss and/or wiring expense for distant panels
- freedom to change battery voltage
Several years ago, I picked up some surplus panels that were custom-designed for a specific grid-tie application: they had a Voc of 25V -- useless with a PWM controller. With 3 in series (no combiner box!), an MPPT controller could charge batteries at 12V, 24V, or 48V; the high array voltage made for negligible loss over a long run of #10 wire. In this design, the "expensive" MPPT controller saved way more money than it cost -- and the system still charges (a little) when the panels are in the shade.
Oversimplification of best use case.
MPPT allows your panel array to run at a different voltage than your batteries.
- smaller combiner boxes -- or none at all
- surplus panels with "weird Voc" work great
- reduced power loss and/or wiring expense for distant panels
- freedom to change battery voltage
Several years ago, I picked up some surplus panels that were custom-designed for a specific grid-tie application: they had a Voc of 25V -- useless with a PWM controller. With 3 in series (no combiner box!), an MPPT controller could charge batteries at 12V, 24V, or 48V; the high array voltage made for negligible loss over a long run of #10 wire. In this design, the "expensive" MPPT controller saved way more money than it cost -- and the system still charges (a little) when the panels are in the shade.