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--- opinion:frater_secessus:panelsizesforinsolation [2022/05/08 10:41]
frater_secessus [Solar panel sizing for different geographical areas]
+++ opinion:frater_secessus:panelsizesforinsolation [2024/03/20 00:01] (current)
frater_secessus [Amount of solar wattage required per 100Ah of Pb]
@@ Line 10: / Line 10: @@
 This page is a rough attempt to show how geographical location and meteorological conditions affect the amount of solar wattage one needs.
-**Reminder:**  available sunlight ([[electrical:solar:output#insolation|insolation]]) is expressed in Hours of Full Sun Equivalent (FSE) compared to lab conditions.  So an entire cloudy day might provide only 2 hours of FSE, meaning it would be the same amount of sunlight as 2 hours of full sunlight under lab conditions (1000w/sq meter).  Therefore **2 hours of FSE = 2kWh**.((and 7.2MJ (megajoules) for our metric friends))  Multiply [FSE for the time/place] x [rated panel wattage] to see what see how many watts your system would harvest on average if it were perfectly efficient.((hint:  it's not)).  Example:  4 hours of FSE x 200w = 800Wh, or 0.8kWh, before various losses.((see Assumptions section at bottom for typical losses))
+**Reminder:**  available sunlight ([[electrical:solar:output#insolation|insolation]]) is expressed in Hours of **Full Sun Equivalent (FSE)** compared to lab conditions.  So an entire cloudy day might provide only 2 hours of FSE, meaning it would be the same amount of sunlight as 2 hours of full sunlight under lab conditions (1000w/sq meter).  Therefore **2 hours of FSE = 2kWh**.((and 7.2MJ (megajoules) for our metric friends))  Multiply [FSE for the time/place] x [rated panel wattage] to see what see how many watts your system would harvest on average if it were perfectly efficient.((hint:  it's not)).  Example:  4 hours of FSE x 200w = 800Wh, or 0.8kWh, before various losses.((see Assumptions section at bottom for typical losses))
 Historical weather info is also used to calculate FSE, so good/bad weather is already baked into the average.
-Ambient temperatures also affect panel output, and that is silently factored into the bottom table.
@@ Line 41: / Line 41: @@
 These are crude estimates about the panel wattage required to fully charge 100Ah of AGM from 50% DoD each day.  See the list of assumptions below the chart.
-^ Location       ^ [[electrical:solar:charge_controller#mppt|MPPT]] only  ^ [[electrical:solar:charge_controller#pwm|PWM]] only  ^ w/ [[electrical:12v:alternator|isolator]]  ^ w/ [[electrical:12v:b2b|DC-DC charger]] or [[electrical:generator|generator]]  ^
+^ Location       ^ [[electrical:solar:charge_controller#mppt|MPPT]] only  ^ [[electrical:solar:charge_controller#pwm|PWM]] only  ^ w/ [[electrical:12v:alternator|"isolator"]]  ^ w/ [[electrical:12v:b2b|DC-DC charger]] or [[electrical:generator|generator]]  ^
 | Seattle - avg  | 280w                                                   | 329w                                                 | 140w                                       | 103w                                                                           |
 | Seattle - Dec  | 921w                                                   | 1056w                                                | 528w                                       | 388w                                                                           |
@@ Line 56: / Line 56: @@
 Assumptions:
+  * panel output is temperature-derated according to daily average high at each time/place
   * **no other loads** other than charging are present
-  * AGM deep cycle battery is discharged to [[electrical:depth_of_discharge|50% DoD]] nightly and [[electrical:12v:charging|fully charged]] the next day
+  * AGM deep cycle battery is discharged to [[electrical:depth_of_discharge|50% DoD]] nightly and [[electrical:12v:charging|fully charged]] the next day.  Charging efficiency 90%.
   * MPPT controller is 95% efficient
   * PWM yields, overall, 85% of MPPT yield.  PWM yields will be quite close to MPPT yields when other forms of charging is present, as PWM will no longer be [[electrical:solar:pwm_tweaking|hamstrung by low Vbatt]].
@@ Line 64: / Line 65: @@
   * [[electrical:solar:output#panel_temperature|temperature-related derating]] baked in based on monthly average high temperatures
   * due to lower internal resistance **lithium will accept more charge from alternator/generator** than AGM by the time it reaches the charging source's voltage setpoint, thereby requiring somewhat less panel wattage. Likewise, flooded batteries will accept //less// than AGM and then require more panel.
-  * solar-only charging the same number of amps into lithium would require about 15% less panel than lead due to better charging efficiency.  Lithium can be charged successfully off alternator/generator only so no panel would be required.
+  * solar-only charging the same number of amps into lithium would require about 10% less panel than AGM due to better charging efficiency.  Lithium can be charged successfully off alternator/generator only so [[electrical:12v:mandatory_solar|no panel would be required]].
+===== further reading =====
+  * factors affecting [[electrical:solar:output|solar harvest]]

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