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--- electrical:solar:mppt_design [2021/07/19 23:35]
frater_secessus [MPPT integration]
+++ electrical:solar:mppt_design [2021/07/19 23:40]
frater_secessus [input voltage]
@@ Line 7: / Line 7: @@
 Worst case scenario:
-  * poly panel with 17v Vmp
+  * low Vmp 12v panel, like a poly panel with Vmp of 17v
-  * 90F ambient temps which derates panel by 18% (Vmp is now 13.94)
+  * 90F ambient temps,  which derates panel by 18% (Vmp is now 13.94)
   * wiring losses of 2% (panel voltage entering controller is now 13.66v)
-  * a controller that requires Vbatt + 1v to do MPPT
+  * a controller that requires Vbatt + 1v to maintain MPPT operation
+...means the controller can't do MPPT charging above 12.66v;  we have effectively wasted our money on that $$ MPPT controller.  So make sure there is sufficient (voltage) headroom for the MPPT to operate:
+  * higher-Vmp panels
+  * higher-voltage panels
+  * panels in series
-...means the controller can't do MPPT charging above 12.66v;  we have effectively wasted our money on that $$ MPPT controller.  So make sure you have sufficent (voltage) headroom for the MPPT to operate.  Higher-voltage panels will work, as will panels with higher Vmp specs.  Some high-efficiency 12v mono panels Vmp > 19v.  In our worst-case situation above that would keep us in MPPT up to 14.26v.
-An MPPT controller can also be the centerpiece of [[electrical:converter#diy_converters|a DIY converter]].
@@ Line 32: / Line 36: @@
   * generic rule of thumb:  Vpanel <= maximum Vbatt * 2.((https://www.homepower.com/input-voltage-controller-efficiency))((https://forum.solar-electric.com/discussion/351037/recomended-mppt-input-voltage-for-a-48-volt-system)).
+===== other uses =====
+An MPPT controller can also be the centerpiece of [[electrical:converter#diy_converters|a DIY converter]].

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