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electrical:solar:panels [2023/05/04 20:06] frater_secessus [Panel voltage] |
electrical:solar:panels [2024/05/28 22:01] (current) frater_secessus [efficiency] |
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To avoid overcharging, | To avoid overcharging, | ||
- | [[electrical: | + | [[electrical: |
- | + | ||
- | **As a general rule, expect panels to put out 60% of their rating** | + | |
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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==== Portable ==== | ==== Portable ==== | ||
- | While most panels are hard mounted horizontally on the roof of the van, portable folding | + | While most panels are hard mounted horizontally on the roof of the van, portable solar panels((folding, briefcase, framed or otherwise)) may have some advantages. |
[[https:// | [[https:// | ||
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* Questions exist about long-term durability | * Questions exist about long-term durability | ||
* Possibility of panels getting stolen | * Possibility of panels getting stolen | ||
+ | * not all portables are weatherproof | ||
+ | * can be blown over by wind | ||
+ | Note that regular framed panels can also be carried as portables. | ||
==== half-cut ==== | ==== half-cut ==== | ||
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- | ===== Efficiency | + | ===== efficiency |
+ | |||
+ | The formula for panel efficiency is simply [ rated kW / square meter ]. A 20% efficient panel will make 200w per square meter under lab conditions, ie, 20% of the lab's 1000w standard. (0.20kW per 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. |
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+ | ===== 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:// | ||
- | Mono panels can capture about 15-20% of this visible light energy. | ||
===== Specifications ===== | ===== Specifications ===== | ||
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* **Maximum Power Voltage (Vmp)**: | * **Maximum Power Voltage (Vmp)**: | ||
* **Maximum Power Current (Imp)**: | * **Maximum Power Current (Imp)**: | ||
+ | * **Temperature coefficient**; | ||
Note that in this example the Power (W) rating is 190, which is the Vmp x Imp (28.60 x 6.64 = 189.904W). | Note that in this example the Power (W) rating is 190, which is the Vmp x Imp (28.60 x 6.64 = 189.904W). | ||
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In real world conditions [[electrical: | In real world conditions [[electrical: | ||
- | Panels | + | ==== temperature coefficient ==== |
+ | |||
+ | Panel voltage // | ||
+ | |||
+ | - since panels are rated by Vmp x Imp, anything that reduces voltage will reduce power.((PWM are generally not affected since they are not using that higher voltage anyhow)) | ||
+ | - the Vmp your MPPT controller finds in human-comfortable temps will likely be lower than rated Vmp | ||
+ | |||
+ | Example: | ||
+ | |||
+ | The actual amount of drop is dictated by the **temperature coefficient**, | ||
+ | |||
+ | This coeffcient ranges from 0.3% to -0.5%. | ||
+ | |||
+ | Let's consider three different panels in 80F ambients: | ||
+ | |||
+ | * 100w mono, rated 19Vmp, -0.445%/ | ||
+ | * 100w poly, rated 18Vmp, -0.440%/ºC == **14.48w** lost @ 15.39Vmp | ||
+ | * 100w CIGS((not really, trying for apples-to-apples here)), rated 18.66Vmp, -0.36%/ºC == **11.85w** lost @ 16.45Vmp | ||
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+ | |||
+ | |||
==== STC and NOCT ==== | ==== STC and NOCT ==== | ||
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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:// | **PTC** ([[https:// |