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--- electrical:solar:panels [2020/01/14 16:23]
frater_secessus [flexible]
+++ electrical:solar:panels [2020/06/16 16:06]
frater_secessus [panel voltage]
@@ Line 3: / Line 3: @@
 Solar panels, also called photovoltaic (PV) panels, produce DC power from sunlight to charge batteries and provide electrical power.  The panels can be used single or in [[electrical:solar:series vs parallel|series or parallel]] arrays.
-Since PV necessarily run at higher voltages than the batteries they charge, a [[electrical:solar:charge controller|charge controller]] is placed between the PV and the battery bank.
+To avoid overcharging,((a bit of an oversimplification, admittedly)) a [[electrical:solar:charge controller|charge controller]] is placed between the PV and the battery bank.
 [[electrical:solar:output|Many factors]] will affect output; and panels will rarely generate power equal to their laboratory rating.
@@ 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 56: / Line 57: @@
-Flex panel started out as thin film (see below) but has moved to crystalline cells since 2018.
+The other challenge is to make solar cells that can slightly flex.
 === crystalline ===
-While the flex panel market has largely gone to poly/mono crystalline, there are obvious issues related to making flexible objects out of brittle silicon crystals.  Handle with care, and bend as little as possible.
+While the flex panel market has largely gone to poly/mono crystalline, there are obvious issues related to making flexible objects out of brittle silicon crystals.  It is not clear why the market went that direction.
+Handle with care, and bend as little as possible.
 === thin film ===
@@ Line 122: / 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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