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opinion:frater_secessus:panelsizesforinsolation [2020/06/24 18:23]
frater_secessus [Amount of solar wattage required per 100Ah of Pb]
opinion:frater_secessus:panelsizesforinsolation [2024/03/20 00:01] (current)
frater_secessus [Amount of solar wattage required per 100Ah of Pb]
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 This page is a rough attempt to show how geographical location and meteorological conditions affect the amount of solar wattage one needs.  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.  Historical weather info is also used to calculate FSE, so good/bad weather is already baked into the average.+**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.  
  
  
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 ===== Amount of solar wattage required per 100Ah of Pb ===== ===== Amount of solar wattage required per 100Ah of Pb =====
    
-These figures have [[electrical:solar:output#panel_temperature|temperature-related derating]] baked in, then are rounded off to usable numbers+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.  
  
-Assumptions:  +^ 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]] 
-  * battery is discharged to [[electrical:depth_of_discharge|50% DoD]] nightly+| Seattle - avg  | 280w                                                   | 329w                                                 | 140w                                       | 103w                                                                           | 
 +| Seattle - Dec  | 921w                                                   | 1056w                                                | 528w                                       | 388w                                                                           | 
 +| Seattle - Jul  | 163w                                                   | 192w                                                 | 82w                                        | 60w                                                                            | 
 +|                |                                                        |                                                      |                                            |                                                                                | 
 +| SLC - avg      | 238w                                                   | 281w                                                 | 119w                                       | 88w                                                                            | 
 +| SLC - Dec      | 473w                                                   | 556w                                                 | 236w                                       | 174w                                                                           | 
 +| SLC - Jul      | 156w                                                   | 183w                                                 | 78w                                        | 57w                                                                            | 
 +|                |                                                        |                                                      |                                            |                                                                                | 
 +| Phoenix - avg  | 200w                                                   | 235w                                                 | 100w                                       | 73w                                                                            | 
 +| Phoenix - Dec  | 369w                                                   | 434w                                                 | 184w                                       | 135w                                                                           | 
 +| Phoenix - Jul  | 149w                                                   | 175w                                                 | 74w                                        | 55w                                                                            | 
 + 
 +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.  Charging efficiency 90%.
   * MPPT controller is 95% efficient   * 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]].   * 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]].
-  * isolator charging is done in early morning, and discontinued when alternator no longer raises voltage.  At this point ~70% of charging will be done.  +  * [[electrical:12v:alternator|isolator charging]] is done in early morning, //every// morning, at ~[[electrical:12v:battery_capacity|C]]/3((~33A, AGM max charging current)), and discontinued when alternator no longer raises voltage.((~14.4v?))  The chart assumes at that point [[opinion:frater_secessus:charging_faster|~50% of charging will be done]].  
-  * DC-DC (or generator) charging is is done in early morning, and discontinued when Vabs is achieved.  At this point 85% of charging will be done.   +  * [[electrical:12v:b2b|DC-DC]] (or [[electrical:generator|generator]]) charging is is done in early morning //every// morning, at C/3,((~33A, AGM max charging current)) and discontinued when Vabs is achieved((!4.7v)).  We assume at this point 63.3%% of charging will be done.  The practical difference between alternator charging and DC-DC or generator charging is the latter will charge all the way to Absorption voltage.  
-  * wattage listed as ''any'means "any amount over 100w"+  * [[electrical:solar:output#panel_temperature|temperature-related derating]] baked in based on monthly average high temperatures 
-  * solar-only charging the same number of amps into lithium would require about 15% less panel than lead.  Lithium can be charged successfully off alternator/generator only so no panel would be required. +  * 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 wattageLikewise, 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 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 =====
  
-^ 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]] +  * factors affecting [[electrical:solar:output|solar harvest]]
-| Seattle - avg  | 250w       | 300w      | any         | any                           | +
-| Seattle - Dec  | 950w       | 1100w     | 275w        | 150w                          | +
-| Seattle - Jul  | 150w       | 175w      | any         | any                           | +
-|                |            |                                                     | +
-| SLC - avg      | 200w       | 250w      | any         | any                           | +
-| SLC - Dec      | 425w       | 500w      | 125w        | any                           | +
-| SLC - Jul      | 150w       | 175w      | any         | any                           | +
-|                |            |                                                     | +
-| Phoenix - avg  | 175w       | 200w      | any         | any                           | +
-| Phoenix - Dec  | 325w       | 400w      | any         | any                           | +
-| Phoenix - Jul  | 125w       | 150w      | any         | any                           |+
opinion/frater_secessus/panelsizesforinsolation.1593037438.txt.gz · Last modified: 2020/10/11 19:48 (external edit)