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Solar panels + cold = A potential problem

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Re: Solar panels + cold = A potential problem

#191

Post by numpad0 »

adrian_b wrote: post #67
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!?

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.

Makes me wonder if that was how EV DCFC quickly settled with 400VDC. The voltage makes sense if it was somehow known that engineers has intuitions with safe designs for 400Vp-p systems.

Re: Solar panels + cold = A potential problem

#192

Post by necovek »

cameronh90 wrote: post #148
teiferer wrote: post #25

Maybe they should just improve their product to make it more resiliant, rather than blaming customers for thinking that 148 V is below 150 V? 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. And no matter what happens, customer support should help the customer, not blame them.

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…

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).

Re: Solar panels + cold = A potential problem

#193

Post by geocar »

cjbgkagh wrote: post #173
geocar wrote: post #154

Earlier quoted context omitted.

> I have a lot of electronics that accept 100-240v doesn’t mean I think they’re close together, just that they have compensating mechanisms to handle such voltages. I bet you also have a lot of electronics that don't though, and those that do probably say so. My kitchen mixers, dishwasher, washing machine, driers, rice cooker, refrigerators, sauna, and pool pump aren't that tolerant by a long shot. I've got a few com…

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 different voltages, so I think voltages within that range are roughly equivalent.

Furthermore, British have such a very special relationship with tea, such it would be entirely understandable that a Brit would take their kettle with them and often become quite annoyed that they cannot get an adapter to use it when holidaying amongst the yanks.

Re: Solar panels + cold = A potential problem

#194

Post by necovek »

numpad0 wrote: post #191
adrian_b wrote: post #67

Earlier quoted context omitted.

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.

Makes me wonder if that was how EV DCFC quickly settled with 400VDC. The voltage makes sense if it was somehow known that engineers has intuitions with safe designs for 400Vp-p systems.

I would be wary of relating any DC constraints to AC constraints and behaviour.

Re: Solar panels + cold = A potential problem

#195

Post by jama211 »

majorchord wrote: post #139
hyperhello wrote: post #125

Earlier quoted context omitted.

Why does this kind of comment get downvoted that pinpoints the actual motivation? We just pretend that planned obsolescence is history.

At least in parent's case, probably because the vast majority of their comments are black-and-white hot takes that are always downvoted regardless. And they basically never respond when asked for any sources.

Yeah bad faith commenter then

Re: Solar panels + cold = A potential problem

#196

Post by necovek »

shepherdjerred wrote: post #179
syntaxing wrote: post #150

Earlier quoted context omitted.

> There's a reason people don't install electric equipment without training. I’m not sure if I follow that logic and if your analogy follows. I would argue this is closer plugging in an appliance rather than running wires. If I run a 15A appliance on a 10A breaker, a normal person without training would expect the breaker to trip. This is like running a 10A appliance and the 15A breaker trips because the appliance is…

> If I run a 15A appliance on a 10A breaker, a normal person without training would expect the breaker to trip. Would the breaker trip in this case? I thought in this case it'd be more likely to start a fire. Edit: thinking about this more, I think I'm wrong. A fire would start if your wires were too thin for a given amperage. Breakers detect current flowing.

Yeah, you were wrong: 15A on thin wires would heat them up too much and could cause a fire after prolonged runtime.

A 10A breaker breaks the circuit much faster than it takes for the wires to heat up, thus stopping the current flow.

Re: Solar panels + cold = A potential problem

#197

Post by hyghjiyhu »

londons_explore wrote: post #184
londons_explore wrote: post #183

Solar inverters could be designed smarter. Today's inverters have a volt limit and an amp limit and you must stay within both. But physics doesn't require that - you could instead design a solar inverter where you could stay within either ! It would work by detecting when one limit (volts or amps) was about to be exceeded, and pushing the operational point away from there. Remember that for solar there are two zero p…

Worth noting that the physics of electricity has an odd symmetry between voltage, power and current which means almost any circuit can be redesigned to effectively switch around all V's and I's and still work. It is mere convention that we have decided that V should usually be regulated and constant and a property of the supply whilst I is variable and determined by the load.

Chemical batteries naturally supply a fixed voltage. You can have a fixed voltage over an open circuit without losing energy.

Re: Solar panels + cold = A potential problem

#198

Post by immibis »

jama211 wrote: post #195
majorchord wrote: post #139

Earlier quoted context omitted.

At least in parent's case, probably because the vast majority of their comments are black-and-white hot takes that are always downvoted regardless. And they basically never respond when asked for any sources.

Yeah bad faith commenter then

Voting based on ad hominem is against HN guidelines.

Re: Solar panels + cold = A potential problem

#199

Post by Faaak »

namibj wrote: post #143
Faaak wrote: post #85

Last year, I did yet another PV install at a friends house. While plugging the SMA inverter to the solar field (600V), I fucked up and inverted plus & minus. Nothing happened. I read the manual and realised that SMA inverters are protected against reverse polarity. Yeah, a bit more expensive, but well worth it

I'm more surprised you managed to plug them in reversed; did you have good reason to avoid the polarized semi-pwrmanently-latching connects that most panels ship with?

Because panels are on the roof, the inverter is on the basement, so you have to run your own cables and crimp the mc4 connectors on them. If you swap them around they get mixed up ;-)

Re: Solar panels + cold = A potential problem

#200

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...

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