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Solar panels + cold = A potential problem

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Re: Solar panels + cold = A potential problem

#61

Post by uyzstvqs »

taneq wrote: post #47
uyzstvqs wrote: post #43

Sounds to me like someone is misrepresenting their products. A solar panel's VoC should be its maximum possible output in ideal conditions (open circuit). If that's under your product's maximum input voltage, it should be no problem. Ever. Is EcoFlow advertising a higher input voltage than their products can actually take, assuming most people won't actually reach it due to temperature inefficiencies? That'd be false…

What does “maximum possible voltage” mean for a solar panel? Do you include things like cloud edge effect (which increases incident light beyond direct sunlight?) What about installs with a nearby window reflecting light onto the panel? Do you include ultra-cold environments (which will reduce the resistance and therefore often increase voltage, although admittedly not, I think, Voc)?

VoC is the maximum potential voltage a cell is physically capable of producing. It does not consider real-world conditions. Rather, real-world conditions cause the solar panel's output voltage to be somewhere between 0 and its VoC.

Re: Solar panels + cold = A potential problem

#62

Post by jimnotgym »

numpad0 wrote: post #55
_9ptr wrote: post #53

Earlier quoted context omitted.

Obviously you include everything, otherwise it wouldn't be a maximum. You can define a minimum temperature for this, of course, but the customer should know about it.

There's no theoretical maximum voltages for solar panels like there kind of is for batteries. They're just giant array of photodiodes and they just generate whatever voltage potentials proportionate to amount of lights received. You could produce a "max voltage flying low earth orbit over Gobi with no shadows from Starlinks" value, but that's just the value for circumstantial most absurd situation you happened to hav…

So it is doubly important that all equipment downstream has overvoltage protection?

In fact considering there is no theoretical maximum, it would be downright negligent not to have overvoltage protection

Re: Solar panels + cold = A potential problem

#63

Post by maccard »

nenenejej wrote: post #20

Why isn't there code/regulations for tbis. Why do you need blog advice. It is like using too thin wiring to your oven or something. Because you based it off how you typically use the oven not is max draw plus decent margin. Which is why you get a qualified electrician who knows or get qualified yourself.

> Why isn't there code/regulations for tbis. Why do you need blog advice.

On pretty much every other device (domestic for sure, I don't actually know abount commercial) there is.

> It is like using too thin wiring to your oven or something. Because you based it off how you typically use the oven not is max draw plus decent margin.

Sure, but with all other electrical labelling the numbers are correct. Imagine if Neff said "you only need an 13A rated socket" for their oven, and then when you want to bake bread it draws more. That's very different to Neff saying "you need 45A", and deciding to install it on a 13A socket yourself because you don't need to make bread. The former is what's happening in this case.

Re: Solar panels + cold = A potential problem

#65

Post by rzzzt »

numpad0 wrote: post #58
geocar wrote: post #29

Earlier quoted context omitted.

> Not everybody buying these has a Ph.D. in physics and if it says 148 V on the label and 150 V on the other label then it's your product that has a problem, not the customer. Idk. I don't have a PHD, but 220V sounds like 240V to me. I wouldn't do this. I feel like getting advice about how to wire up electronics should not be so hard. > Maybe they should just improve their product to make it more resiliant Adding "re…

> Idk. I don't have a PHD, but 220V sounds like 240V to me. I wouldn't do this. 220[Vrms] * 1.414 = 311[Vp-p] btw. HOW!?

AC wiggles and wobbles.

Re: Solar panels + cold = A potential problem

#66

Post by mazurnification »

numpad0 wrote: post #58
geocar wrote: post #29

Earlier quoted context omitted.

> Not everybody buying these has a Ph.D. in physics and if it says 148 V on the label and 150 V on the other label then it's your product that has a problem, not the customer. Idk. I don't have a PHD, but 220V sounds like 240V to me. I wouldn't do this. I feel like getting advice about how to wire up electronics should not be so hard. > Maybe they should just improve their product to make it more resiliant Adding "re…

> Idk. I don't have a PHD, but 220V sounds like 240V to me. I wouldn't do this. 220[Vrms] * 1.414 = 311[Vp-p] btw. HOW!?

So the issue is that 220V is nominal in China, 230V nominal in UE and 240V is UK/part of Australia. So if anyone is preparing product for global market (as most are doing now) more likely then not will support all of this voltages. Thus is kind of normal (but wrong) to assume 220V sounds like 240V.

Re: Solar panels + cold = A potential problem

#67

Post by adrian_b »

numpad0 wrote: post #58
geocar wrote: post #29

Earlier quoted context omitted.

> Not everybody buying these has a Ph.D. in physics and if it says 148 V on the label and 150 V on the other label then it's your product that has a problem, not the customer. Idk. I don't have a PHD, but 220V sounds like 240V to me. I wouldn't do this. I feel like getting advice about how to wire up electronics should not be so hard. > Maybe they should just improve their product to make it more resiliant Adding "re…

> Idk. I don't have a PHD, but 220V sounds like 240V to me. I wouldn't do this. 220[Vrms] * 1.414 = 311[Vp-p] btw. HOW!?

Besides the ratio between the peak and effective value, you must also account for the standard tolerance of the nominal value.

The actual maximum peak voltage for the European mains, is 230 V * 1.15 * sqrt(2), because of a 15% tolerance. That is about 375 V. With a small safety margin, the minimum voltage rating for components connected to 230 V a.k.a. 220 V is of 400 volt.

Re: Solar panels + cold = A potential problem

#69

Post by adrian_b »

mazurnification wrote: post #66
numpad0 wrote: post #58

Earlier quoted context omitted.

> Idk. I don't have a PHD, but 220V sounds like 240V to me. I wouldn't do this. 220[Vrms] * 1.414 = 311[Vp-p] btw. HOW!?

So the issue is that 220V is nominal in China, 230V nominal in UE and 240V is UK/part of Australia. So if anyone is preparing product for global market (as most are doing now) more likely then not will support all of this voltages. Thus is kind of normal (but wrong) to assume 220V sounds like 240V.

When the voltage was unified in UE, the nominal value was set to the median of 230 V, but its tolerance was raised from 10% to 15%, so that the new maximum peak value of 230V + 15% will match the old value of 240 V + 10%.

So now for all 220/230/240 V standards you have the same maximum voltage value that is used for electrical designs (about 265 V effective), so they are equivalent, regardless of the name.

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