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Solar panels + cold = A potential problem

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Re: Solar panels + cold = A potential problem

#221

Post by cameronh90 »

jama211 wrote: post #163
cameronh90 wrote: post #148

Earlier quoted context omitted.

I don’t know about the components they’re selling, but with electronic components, it’s on the buyer to properly read the data sheet and understand what the quoted nominal specs mean. Unless it’s safety critical, you usually don’t want a system with a bunch of active electronics to prevent someone wiring it up wrong, because those components will interfere with whatever you’re hooking it up to, such as the MPPT, the…

This isn’t electronic components, this is sold as a consumer level gadget that anyone can use. No one expects a standard consumer to understand data sheets like that. You started off by saying you don’t know about the components they’re selling - but that turns out to be absolutely critical to understanding the context here. Either way, I can’t believe they just let it fry the main board instead of having a sacrifici…

I don't know how this would be perceived in the US, but in UK/Europe this wouldn't be seen as or regulated as a "consumer level gadget".

It's a main-voltage electrical system. I'm not even sure it would be legal for an electrician without the appropriate qualifications to commercially commission one of these systems. Their website even says installations should be performed by "a licensed electrician or a qualified professional."

In practice, every single solar system I've seen is exactly the same as this one.

A fuse wouldn't help here because they're current protection devices but we're talking about voltages here. Voltages are harder to generically protect against with a sacrificial device, and also over-voltage protection devices themselves have a habit of catching fire even when the voltage is within limits so you probably don't want one right next to your lithium batteries anyway. You'll even find most consumer devices don't have much in the way of continuous overvoltage protection.

It's typical when commissioning solar to just "protect" from panel overvoltage by ensuring your panel outputs are well within the margin of your MPPT (this device appears to be an a combined MPPT, inverter and battery) on a worst case cold day. Really there's just no reason to run your panels right up against the MPPT max voltage.

Given how easy it is to protect against design overvoltage by designing your panel circuits suitably, and how overvoltage protection devices are themselves a point of (potentially catastrophic) failure, I think it's pretty hard to make the case for including one as standard, which is why nobody does.

But leaving this particular issue aside, these devices are totally not suitable for consumer installations unless you like fires.

Re: Solar panels + cold = A potential problem

#222

Post by necovek »

cameronh90 wrote: post #220
necovek wrote: post #192

Earlier quoted context omitted.

In your AA batteries analogy, this is like saying that you do not need to state that the device exploding at 1.55V would do so, not about battery declarations (panels in this case).

It wasn't meant to be a direct analogy, just a simple example of how you get similar situations in general with electronic components, or really any kind of non-standalone component in most industries. Another example is fuses: a fuse rated at 20A will not immediately protect the downstream once load exceeds 20A, but rather, there will be a curve defined with respect to its nominal rating which defines how long it wi…

Got it, thanks for diving deeper!

Re: Solar panels + cold = A potential problem

#223

Post by mazurnification »

adrian_b wrote: post #69
mazurnification wrote: post #66

Earlier quoted context omitted.

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.

True, however there is also old equipment. For example I have heard that light bulbs designed for 220V will last for noticeably shorter period of time ar 230V nominal circuit. That is why it is worth to check supported voltage. But you are right - newer equipment will suport all voltages.

Re: Solar panels + cold = A potential problem

#225

Post by pfdietz »

gsf_emergency_2 wrote: post #188
pfdietz wrote: post #103

Earlier quoted context omitted.

https://web.stanford.edu/group/fan/publication/Li_ACSPhotoni...

Ah yes, a paper from Fan Shanhui's group at Stanford, which kicked off the whole business. Should have linked that instead! This is 5.7 deg (using metasurfaces to selectively reflect reflect absorb different wavelengths) compared to a less fancy 4.9 deg from their seminal paper (2014) https://www.nature.com/articles/nature13883 Maybe comparable cooling can be achieved with even cheaper techniques..?

The interesting implication is that PV has more upside growth potential than nuclear, against the ultimate limit of global thermal pollution.

Re: Solar panels + cold = A potential problem

#226

Post by necovek »

unglaublich wrote: post #44
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.

Okay, but the oven tells you: use at least 8mm^2 wire, and then it goes up in flames because hey sometime you actually need 10mm^2...

Quote from the internet in reference to 10mm2 wire gauge:

"This metric wire size is common in industrial settings for high-power devices and main circuits where thicker conductors are needed for safety and efficiency."

That would be quite some oven.

Re: Solar panels + cold = A potential problem

#228

Post by namibj »

dotancohen wrote: post #147
namibj wrote: post #137

Earlier quoted context omitted.

Don't bother; at that point just plug them into 200~300 V DC right to the battery (with just fuse and meter between, no need for any conversion, the washer motor controller that'd be needed to utilize a capacitor for smoothing these spikes would do just fine on a reasonable battery charge/discharge voltage spread.

Do any home battery systems, or home appliances, actually support this?

Most electronic power supplies for computers and similar devices (like e.g. modern TV) have zero complaints about being fed such DC.

Sadly only those that try to sell to Alirack applications (i.e., Chinese server PSU's like for example Lenovo Servers) bother testing in QA and doing enough design review to officially claim that support on their data plate.

You can tear down a sacrifice from a series of identical consumer PSUs though, and reverse engineer the front end schematic to check that the AC side of the active power factor correction design that you'd find in e.g. a decent gaming PSU doesn't do anything that would react badly to a lack of AC.

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