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electrical:solar:panels [2022/01/15 02:51] princess_fluffypants |
electrical:solar:panels [2024/01/04 16:54] (current) frater_secessus [STC and NOCT] compare |
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To avoid overcharging, | To avoid overcharging, | ||
- | [[electrical: | + | [[electrical: |
There are several types of PV widely available on the market, and many more in research stages. | There are several types of PV widely available on the market, and many more in research stages. | ||
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* slightly better than poly in uniform low light | * slightly better than poly in uniform low light | ||
* theoretically greater longevity than poly, much better longevity than thin film | * theoretically greater longevity than poly, much better longevity than thin film | ||
- | * slightly higher [[electrical: | + | * slightly higher [[electrical: |
* slightly better performance in higher temps than poly, possibly due to higher Vmp | * slightly better performance in higher temps than poly, possibly due to higher Vmp | ||
* CON | * CON | ||
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* semi-flexible so it can be applied to curved shapes | * semi-flexible so it can be applied to curved shapes | ||
* least affected by high temps | * least affected by high temps | ||
- | * least affected by shading | + | * least affected by shading |
+ | * least affected by cloudy/hazy conditions, due to increased sensitivity at the blue end of the light spectrum((https:// | ||
* very light | * very light | ||
* CON | * CON | ||
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* lower Vmp | * lower Vmp | ||
- | ===== Portable | + | ==== Portable ==== |
While most panels are hard mounted horizontally on the roof of the van, portable folding portable solar panels have dropped in price and have some advantages. | While most panels are hard mounted horizontally on the roof of the van, portable folding portable solar panels have dropped in price and have some advantages. | ||
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* can collect sunlight while the camper stays in the shade | * can collect sunlight while the camper stays in the shade | ||
* Can be angled and moved follow the sun and collect maximum power | * Can be angled and moved follow the sun and collect maximum power | ||
- | * Sometimes have USB charging ports directly on the back of them | + | * Sometimes have USB charging ports directly on the back of them, allowing charging of small devices directly without the use of a charge controller and battery setup. |
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- | ---- | + | ==== half-cut ==== |
+ | |||
+ | Some panels are "half-cut" which means the cells are cut in half and wired to make 2x as many cells. | ||
+ | |||
+ | {Secessus reminds us we should avoid [[electrical: | ||
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- | * **Nominal 12v panels** have 36 cells. | + | * **Nominal 12v panels** have 36 cells. |
* **Nominal 20v panels** have 60 cells. | * **Nominal 20v panels** have 60 cells. | ||
- | * **Nominal 24v panels** have 72 cells. | + | * **Nominal 24v panels** have 72 cells. |
+ | * even higher | ||
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higher voltage panels are more common on the used market, as people upgrade residential/ | higher voltage panels are more common on the used market, as people upgrade residential/ | ||
- | MPPT [[electrical: | + | MPPT [[electrical: |
Higher voltage panels can reduce wire costs; amps are cut in half for the same amount of wattage. | 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. | + | They are more likely to stay above charging setpoints in poor insolation or high heat. |
Panel voltage((more precisely, the relationship between panel voltage and battery voltage)) is an important factor when [[electrical: | Panel voltage((more precisely, the relationship between panel voltage and battery voltage)) is an important factor when [[electrical: | ||
- | ===== Efficiency | + | |
+ | |||
+ | ===== efficiency | ||
+ | |||
+ | The formula for panel efficiency is simply rated watts / square meter. | ||
Higher efficiency doesn' | Higher efficiency doesn' | ||
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In general, mono has higher efficiency than poly, and poly has higher efficiency than thin film. | 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. | + | 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. |
+ | |||
+ | |||
+ | |||
+ | ===== longevity ===== | ||
+ | |||
+ | Framed panels are often warranted to make 80% of their rated output for 25+ years. | ||
+ | There is [[https:// | ||
- | > At zenith, sunlight provides an irradiance of just over 1 kilowatt per square meter at sea level. Of this energy, 527 watts is infrared radiation, **445 watts is visible light**, and 32 watts is ultraviolet radiation. -- [[https:// | ||
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PV are generally rated by several criteria((http:// | PV are generally rated by several criteria((http:// | ||
- | * **Power (W)**: 190 Watts. | + | * **Power (W, or Pmax)**: 190 Watts. |
* **Open Circuit Voltage (Voc)**: | * **Open Circuit Voltage (Voc)**: | ||
* **Short Circuit Current (Isc)**: | * **Short Circuit Current (Isc)**: | ||
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While NOCT may be useful for gauging normal harvests, STC is used for system component((like controllers)) sizing because the panels really can make STC power((or even more)) in some real world conditions. | While NOCT may be useful for gauging normal harvests, STC is used for system component((like controllers)) sizing because the panels really can make STC power((or even more)) in some real world conditions. | ||
+ | >> NOCT is useful for comparing two panels **[that have] the same STC rating**. A panel with a higher rated power at NOCT for example, will generally result in a higher performing panel.((https:// | ||
+ | |||
+ | **PTC** ([[https:// | ||
===== Diodes ===== | ===== Diodes ===== | ||