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electrical:solar:overpaneling [2018/05/10 22:06] frater_secessus [clipping is relatively uncommon] |
electrical:solar:overpaneling [2023/11/22 10:31] frater_secessus [vs. charge controller] |
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**Overpaneling** has two related meanings; | **Overpaneling** has two related meanings; | ||
- | * [[# | + | * Most common meaning: |
- | * [[# | + | * Less common meaning: |
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The overpaneled system' | The overpaneled system' | ||
- | **Example: | + | With appropriate overpaneling the clipping is relatively minor. |
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+ | >> Generally total energy harvested from a 130% panel oversizing results in less than 1% annual energy loss. -- [[https:// | ||
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+ | ==== theory ==== | ||
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+ | Consider the image to the right.((The image is that of a different PV-related configuration but it works for our purposes.)) The smaller/ | ||
The larger/ | The larger/ | ||
The striped area is the peak power " | The striped area is the peak power " | ||
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* you want to get deeply cycled batteries charging as early as possible in the morning | * you want to get deeply cycled batteries charging as early as possible in the morning | ||
* you spend most of your time in areas with [[electrical: | * you spend most of your time in areas with [[electrical: | ||
+ | * you spend time in partial shade | ||
* you want to use a smaller controller instead of jumping up to the next size. Example, 43A max output and your choices are 40A or 60A controllers. | * you want to use a smaller controller instead of jumping up to the next size. Example, 43A max output and your choices are 40A or 60A controllers. | ||
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+ | ==== example ==== | ||
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+ | Let's say you want to adhere to Victron' | ||
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+ | * 500w / 14.2v = 35.2A. | ||
+ | * 35.2A on a 30A MPPT is 17.3% overpaneled: | ||
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- when there is very little load being used | - when there is very little load being used | ||
- | This occurs because the PPT controller moves Vpanel toward Voc to reduce current when less is needed but battery voltage is high, as in late Absorption . | + | This occurs because the PPT controller moves Vpanel toward Voc to reduce current when less is needed but battery voltage is high, as in late Absorption. |
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[This section is based on [[https:// | [This section is based on [[https:// | ||
- | Perhaps counterintuiitively, | + | Perhaps counterintuiitively, |
- Overpaneled systems start collecting usable power earlier in marginal light. | - Overpaneled systems start collecting usable power earlier in marginal light. | ||
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The heavy vertical black line((also added by secessus)) comes down from that intersection at 21v.((It also crosses at ~11v but most MPPT downconvert rather than boost, so 11v is not useful.)) | The heavy vertical black line((also added by secessus)) comes down from that intersection at 21v.((It also crosses at ~11v but most MPPT downconvert rather than boost, so 11v is not useful.)) | ||
- | In this case the controller wants to limit panel output to 65w So it runs the panel at 21v. Then it downconverts the excess voltage to amps: it charges the battery((or runs loads)) 5A @ 13v.((this | + | In this case the controller wants to limit panel output to 65w So it runs the panel at 21v, which is a far cry from Vmp. Then it downconverts the excess voltage to amps: it charges the battery((or runs loads)) 5A @ 13v. |
=== corollaries === | === corollaries === | ||
If you have the curve and Vpanel you can derive the power output. \\ | If you have the curve and Vpanel you can derive the power output. \\ | ||
If you have the curve and you know Wpanel you can derive Vpanel. \\ | If you have the curve and you know Wpanel you can derive Vpanel. \\ | ||
- | If you have a lot of time and patience, you can plot Vpanel and Wpanel to draw the curve yourself. | + | If you have a lot of time and patience, you can plot Vpanel and Wpanel to draw the curve yourself. |
- | + | An MPPT controller is //always// **T**racking and using powerpoints, | |
===== vs. battery bank ===== | ===== vs. battery bank ===== | ||
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- | Overpaneling the bank gets lead-acid batteries charged faster and keeps them charged longer than other approaches. | + | Overpaneling the bank gets lead-acid batteries charged faster((faster/ |
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* you want your lead-chemistry batteries to stay as charged as much as possible | * you want your lead-chemistry batteries to stay as charged as much as possible | ||
+ | * you are in an area with relatively little sunshine | ||
* you want to save battery weight | * you want to save battery weight | ||
* you want to reduce battery investment and complexity | * you want to reduce battery investment and complexity | ||
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Since the underbanked system has less capacity will reduce your actual [[electrical: | Since the underbanked system has less capacity will reduce your actual [[electrical: | ||
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+ | Further reading: | ||
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+ | * [[electrical: | ||