Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Solar panels + cold = A potential problem

linspyre.com

Post reply on HN
Print view View original

201–210 of 228 posts

Re: Solar panels + cold = A potential problem

#201

Post by lazide »

rcxdude wrote: post #185
lazide wrote: post #119

Earlier quoted context omitted.

The idea of safety margins has died under the more pressing type - profit margins.

While in general most parts will work beyond their ratings to at least some degree, this isn't really a safety margin. A safety margin is known, rated, and validated, and usually a property of a system as opposed to just one part within it.

That’s what I said?

Usually a system would have a safety margin of at least 1.5x, or 3x or the like.

In this case the design safety margin appears to be…. 1x? Exactly?

Re: Solar panels + cold = A potential problem

#202

Post by quickthrowman »

saghm wrote: post #41
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…

To me, 220 sounds 20 like lower than 240. I have a hunch that this might be a common perception.

US appliances using single-phase power work between 208V and 240V so they work on both residential and commercial electrical systems.

Line-to-line voltage on a three-phase 208V system is 208V, line-to-line on 240V single-phase system is 240V.

Most commercial lighting products are rated for 120V-277V so they work on both residential and commercial (480/277V line-to-neutral single phase voltage is 277V)

Re: Solar panels + cold = A potential problem

#203

Post by [deleted] »

Animats wrote: post #37
quailfarmer wrote: post #22

Earlier quoted context omitted.

High voltage, low RDSON FETs are (slightly) more expensive, and these products are cheap. A better design would use a higher-voltage rated input switch with poor (slow) switching performance, like an IGBT. Don’t design critical infrastructure around EcoFlow hardware.

Fujitsu, which sells MOSFETs for this application, writes: "Firstly devices should be rated at 600V or 650V, as this will generally provide more than adequate protection against the threat of high voltage transients."[1] That's a nice big safety margin. It should hold until the voltage monitoring shuts the whole thing off. Not seeing UL certification on this thing. If we're going to have US protectionism against Chin…

[deleted]

Re: Solar panels + cold = A potential problem

#204

Post by emn13 »

nanomonkey wrote: post #130
emn13 wrote: post #57

Earlier quoted context omitted.

So on the one hand we have a product which isn't even remotely designed for the use case (hamsters), and during normal use shows obvious behaviour (cooking) that should imply risk to said hamsters. On the other side, we have a product designed to be installed in an electrical system, and shows no signs during normal use that it's installed unsafely, and where the advertised specs are not actually safe for normal usag…

Microwaves were originally specifically invented to microwave frozen hamsters: https://interestingengineering.com/videos/1950s-reanimating-...

Hyper amusing, thanks for sharing! Doesn't really improve the analogy, but fun quirk of history :-D.

Re: Solar panels + cold = A potential problem

#205

Post by krageon »

lostlogin wrote: post #157
marcosdumay wrote: post #117

Earlier quoted context omitted.

The entire industry has standardized in having "typical" and "maximum" values decades ago. That problem there is completely self-imposed.

The flip side of this is also dumb labelling. ‘Product may contain traces of nuts’. Completely unhelpful to those that need the info.

That is in fact useful information to someone that needs that info, because it means they should never eat it. I think this is a bad example, because I have no idea what you're talking about.

Re: Solar panels + cold = A potential problem

#206

Post by cjbgkagh »

geocar wrote: post #193
cjbgkagh wrote: post #173

Earlier quoted context omitted.

You’re listing things that are high powered and or old. Modern PSUs don’t have that switch. While it’s in the early stages I expect more white goods to switch to BLDC motors which will likely use voltage transformers that’ll support the 110-240v. People generally are not lugging white goods internationally, the average persons experience with different voltages is for laptop and phone chargers when they travel. But f…

> You’re listing things that are high powered and or old. Sure. I have high-powered and old things, and I bet you've seen stuff like that too. I'm explaining why I, as a non-expert, would not put 146V into something that says it can't take more than 150V. > People generally are not lugging white goods internationally Travel doesn't enter into it; My appliances came from Europe, they're just labelled a bunch of differ…

Not sure what I expected from someone who thinks 208V and 240V are close together from some labels they saw on some devices.

Re: Solar panels + cold = A potential problem

#207

Post by privatelypublic »

rcxdude wrote: post #98
Zanfa wrote: post #34

Earlier quoted context omitted.

This is 100% on the manufacturer if they intentionally chose to highlight the "best case" 150V, rather than the 120V lower end. Especially without any additional safety mechanisms.

The article presents it oddly, it's not that the converter maximum input gets lower, it's the solar panel output that gets higher from the nominal quoted value (which is not a maximum, and not really intended to be used as such). Derating your converter is equivalent for the purposes of ensuring margins, but it implies the issue is in the wrong place.

Open circuit voltage is _very much_ widely considered to be the maximum. If its not spec'd openly as " at temp X" then it's reasonable to expect it to be invariant.

"Voc 37v @ 25*C"

Vs

"Voc 37v"

Edit: Isc is the same- max current.

Re: Solar panels + cold = A potential problem

#208

Post by privatelypublic »

krageon wrote: post #205
lostlogin wrote: post #157

Earlier quoted context omitted.

The flip side of this is also dumb labelling. ‘Product may contain traces of nuts’. Completely unhelpful to those that need the info.

That is in fact useful information to someone that needs that info, because it means they should never eat it. I think this is a bad example, because I have no idea what you're talking about.

Likely a reference to the recent addition of sesame to the allergen disclosure legislation in the US, and the subsequent rampant over labeling.

Nobody seems to remember a bunch of companies receiving rather large fines for pulling known bull-crap "may contain sesame."

Re: Solar panels + cold = A potential problem

#209

Post by privatelypublic »

lazide wrote: post #201
rcxdude wrote: post #185

Earlier quoted context omitted.

While in general most parts will work beyond their ratings to at least some degree, this isn't really a safety margin. A safety margin is known, rated, and validated, and usually a property of a system as opposed to just one part within it.

That’s what I said? Usually a system would have a safety margin of at least 1.5x, or 3x or the like. In this case the design safety margin appears to be…. 1x? Exactly?

Suspiciously so. I'd love to see somebody(or somebodies) with an established reputation reverse the controller software & hardware.
Post reply on HN