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opinion:solar:sizing [2023/10/22 11:04] frater_secessus [solar panels] |
opinion:solar:sizing [2023/12/26 11:54] frater_secessus [battery bank] |
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* if you have undersized solar | * if you have undersized solar | ||
* you have lead-chemistry battery bank | * you have lead-chemistry battery bank | ||
+ | * if charging is time-limited and you want maximal harvest from the alternator, shore, or other high-current charging source. | ||
You will need **somewhat less Ah capacity** | You will need **somewhat less Ah capacity** | ||
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You will **need somewhat more solar** | You will **need somewhat more solar** | ||
- | * if you live in an area with relatively little sun, like the American Northwest. | + | * if you live in an area with relatively little sun, like the American Northwest, Northern Europe, etc. |
* if you want to run more [[electrical: | * if you want to run more [[electrical: | ||
* if you live offgrid full time (FT) or spend long periods [[camping: | * if you live offgrid full time (FT) or spend long periods [[camping: | ||
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* the Ah/Wh to be replaced | * the Ah/Wh to be replaced | ||
- | * the charging efficiency of the battery chemistry (Effectively 100% for Lithium. | + | * the charging efficiency of the battery chemistry (We might ballpark, 99% for Lithium, |
* overall efficiency of the solar setup (we can ballpark 85% for MPPT setups, 70% for PWM) | * overall efficiency of the solar setup (we can ballpark 85% for MPPT setups, 70% for PWM) | ||
- | * [[electrical: | + | * [[electrical: |
- | * minimum charging current requirements, | + | * the contribution of any other charging sources |
+ | * minimum charging current requirements, | ||
Let's assume a 200Ah AGM bank depleted to 50% SoC, wintering in [[camping: | Let's assume a 200Ah AGM bank depleted to 50% SoC, wintering in [[camping: | ||
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- battery charging efficiency of 90% means we need **1333.33Wh of actual charging power** to replace the 1200Wh (1200Wh / 0.90) | - battery charging efficiency of 90% means we need **1333.33Wh of actual charging power** to replace the 1200Wh (1200Wh / 0.90) | ||
- the solar install operates at a 85% efficiency, so we need **1568.63Wh of harvestable sun** power landing on the panels (1333.33Wh / 0.85) | - the solar install operates at a 85% efficiency, so we need **1568.63Wh of harvestable sun** power landing on the panels (1333.33Wh / 0.85) | ||
- | - [[electrical: | + | - [[electrical: |
- So we need **590W of panel** (1568.63Wh / 3.08 hours) | - So we need **590W of panel** (1568.63Wh / 3.08 hours) | ||
- | You may find it easier in the long-term to model this kind of thing in a spreadsheet. | + | In practice you probably won't be drawing your bank to the lowest allowed level each day; substitute your [[electrical: |
+ | **Note**: | ||
==== solar charge controller ==== | ==== solar charge controller ==== | ||