Differences

This shows you the differences between two versions of the page.

--- electrical:solar:charge_controller [2023/09/06 12:05]
frater_secessus [MPPT]
+++ electrical:solar:charge_controller [2023/09/06 12:18]
frater_secessus [PWM]
@@ Line 56: / Line 56: @@
 [[https://diysolarforum.com/threads/why-is-mppt-better-than-pwm.24892/post-295861|For technical reasons]] PWM can deliver more current than the panels' Imp, even nearing Isc.
+=== panel selection for PWM ===
+PWM makes the most power when coupled with panels whose operating [[electrical:solar:panels#specifications|Vmp]] is very close to the controller's Absorption ("boost") voltage [[electrical:solar:charge_controller_setpoints|setpoint]].  Since [[electrical:solar:output#panel_temperature|ambient temperatures affect operating Vmp]] the panel's Vmp spec on the label should be about 10% higher than Absorption voltage.
+Examples:
+  * 16.28v Vmp panel spec would be optimal for 14.8v Absorption, as we might use for flooded lead acid.  14.8v x 1.1 = 16.28v.
+  * 15.62v Vmp panel spec would be optimal for 14.2v Absorption, as we might use for Gel or LiFePO4.
+Some [[electrical:solar:panels#thin_film|thin-film]] panels have Vmp in that range but most panels are much higher.  So we find the lowest Vmp practical.  17Vmp panels would perform better on PWM than 18v or 19v.
 ==== MPPT ====
 [[http://amzn.to/2iD3WKf|{{ https://images-na.ssl-images-amazon.com/images/I/51bi9IjcsRL._AC_US160_.jpg}}]]

RV and vandwellers wiki