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--- electrical:solar:mppt_design [2021/07/19 23:35]
frater_secessus [MPPT integration]
+++ electrical:solar:mppt_design [2023/01/22 15:35] (current)
frater_secessus [input voltage]
@@ Line 1: / Line 1: @@
 ====== MPPT integration ======
-There are benefits from using [[electrical:solar:panels#panel_voltage|higher voltage panels]] that can be realized when a system is designed for an MPPT controller.
+There are benefits from using [[electrical:solar:panels#panel_voltage|higher voltage panels]] that can be realized when a system is designed for an MPPT controller.  $/watt ratios can become quite favorable with large, used panels and [[electrical:solar:overpaneling|overpaneled]] controllers.
-The downside is that MPPT //requires// some amount of excess panel voltage over charging voltage to do its work (see below).  MPPT advantage may be minimal or nonexistant when nominal panel voltage matches nominal battery bank voltage (12v panels and 12v battery, for example).
+The downside is that MPPT //requires// some amount of excess panel voltage over charging voltage to do its work (see below).  MPPT advantage may be minimal or nonexistant when nominal panel voltage matches nominal battery bank voltage (12v panels and 12v battery, for example).  Consider this worst-case scenario:
-Worst case scenario:
+  * 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)
-  * poly panel with 17v Vmp
-  * 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 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.
+In this situation the controller **can't do MPPT charging above 12.66v**;  we have effectively wasted our money on that expensive MPPT.  So make sure there is sufficient (voltage) headroom for the MPPT to operate.  This can be done with higher-Vmp panels((like high-efficiency mono panels)), higher-voltage panels((20-24v)), or panels in series.  Example:  2x 12v panels in series is nominal 24v, a great fit for charging a 12v battery bank.
-An MPPT controller can also be the centerpiece of [[electrical:converter#diy_converters|a DIY converter]].
@@ Line 29: / Line 24: @@
   * SNA (grid tied): Vpanel = desired output * 1.4142((https://www.researchgate.net/profile/Aalok_Bhatt/post/How_to_select_MPPT_Range_of_Solar_Inverter/attachment/59d624496cda7b8083a1f834/AS%3A377507284045824%401467016158673/download/SMA+Datasheet.pdf))
   * EpEver:  Vpanel >= Vbatt +2v to start MPPT.((https://www.epsolarpv.com/upload/cert/file/1811/Tracer-AN(50-100A)-SMS-EL-V1.1.pdf))
+  * Midnite requires Vbatt+30%((https://www.midnitesolar.com/sizingTool/index.php))
   * generic rule of thumb:  Vpanel >= maximum Vbatt + 30%
   * 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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