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--- electrical:solar:panels [2020/05/12 20:40]
frater_secessus [Solar panels]
+++ electrical:solar:panels [2020/11/03 13:31]
frater_secessus [panel voltage]
@@ Line 28: / Line 28: @@
     * most expensive to produce
     * slightly worse than poly in partial shading
+    * ill-suited to [[electrical:solar:charge_controller#pwm|PWM]]/[[electrical:solar:charge_controller#shunt|shunt]] controllers because of their higher voltage (and lower current)
@@ Line 110: / Line 111: @@
-  * **Nominal 12v panels** have 36 cells.  They will generally have max power (Vmp) around 17v and open circuit (Voc) around 21v.((https://www.altestore.com/howto/solar-panels-pv-and-voltages-a98/))  These are commonly found on mobile and portable installations.
+  * **Nominal 12v panels** have 36 cells.  They will generally have max power (Vmp) around 18v and open circuit (Voc) around 21v.((https://www.altestore.com/howto/solar-panels-pv-and-voltages-a98/))  These are commonly found on mobile and portable installations.
-  * **Nominal 20v panels** have 60 cells.  They will generally have max power (Vmp) around 29v and open circuit (Voc) around 36v.((https://www.altestore.com/howto/solar-panels-pv-and-voltages-a98/))  These are commonly found in residential rooftop installations.
+  * **Nominal 20v panels** have 60 cells.  They will generally have max power (Vmp) around 30v and open circuit (Voc) around 36v.((https://www.altestore.com/howto/solar-panels-pv-and-voltages-a98/))  These are commonly found in residential rooftop installations.
-  * **Nominal 24v panels** have 72 cells.  They will generally have max power (Vmp) around 35v and open circuit (Voc) around 42v.((https://www.altestore.com/howto/solar-panels-pv-and-voltages-a98/))  These are commonly found in commercial or residential ground level installations.  Due to internal construction (actually 2 36-cell segments in parallel)((https://youtu.be/ofo1HQyGG8s?t=1m22s)) they can be more resistant to partial shading.
+  * **Nominal 24v panels** have 72 cells.  They will generally have max power (Vmp) around 36v and open circuit (Voc) around 42v.((https://www.altestore.com/howto/solar-panels-pv-and-voltages-a98/))  These are commonly found in commercial or residential ground level installations.  Due to internal construction (actually 2 36-cell segments in parallel)((https://youtu.be/ofo1HQyGG8s?t=1m22s)) they can be more resistant to partial shading.
@@ Line 124: / Line 125: @@
 Higher voltage panels can reduce wire costs; amps are cut in half for the same amount of wattage.
 They more likely to stay above charging setpoints in poor insolation or high heat.
+===== efficiency =====
+Higher efficiency doesn't mean the panel makes more power;  it means it makes more power from a given area.  100w is 100w, but you might be able to fit a 110w panel high-efficiency panel in the same space as a regular-efficiency panel.
+In general, mono has higher efficiency than poly, and poly has higher efficiency than thin film.
+The cost of higher efficiency panels typically outstrips the increase power, so unless you are tight for space they typically aren't a good value for money.  If you are tight for space and need the power then pony up the cash and enjoy the premium product.

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