Solar panels + cold = A potential problem • Hacker News Board

Re: Solar panels + cold = A potential problem

#121

Post by childintime » Sun, Sep 28, 2025, 3:10 PM UTC

fake-name wrote: post #8

franciscop wrote: post #7

I was going to comment on the manufacturer's safety margins, but then I found a graph [1] on the variability of voltage vs temperature and it seems to be a lot steeper than I thought/expected, to the point that I'm wondering how these do not require either training or a voltage regulator to install and operate properly: https://www.researchgate.net/figure/Module-voltage-current-v...

They do! Basically anything that consumes solar power incorporates what's called a "MPPT", or maximum power point tracker. Basically, it's a smart DC-DC converter that continually tracks the voltage/current output of a solar panel and adjusts the load to extract the maximum available power from the panel. It's not uncommon to have issues with extremely high panel voltages in snowy climates, when they're first illumin…

Note it would be sufficient to shut down (short-circuit) a single panel, which is safe, to lower the overall voltage.

Re: Solar panels + cold = A potential problem

#122

Post by Aurornis » Sun, Sep 28, 2025, 3:22 PM UTC

Animats wrote: post #11

Why doesn't this just produce a shutdown? Inverters have to track voltage and current on the input and outputs sides, and can turn themselves off. They shouldn't be that close to the absolute maximum voltage ratings on the components. Too much current is a heat dissipation problem, and you've got some time to deal with that, at least tens of milliseconds. Anyone have a teardown on these things? Are they using under-r…

> They shouldn't be that close to the absolute maximum voltage ratings on the components.

This appears to be a situation where the engineering team determined the absolute maximum input voltage and the marketing/product people put that number straight into the documentation.

Standard practice with electronic parts is to determine the absolute maximum rating, then to specify a recommended maximum that allows for some safety margin and variation.

Instead, this company determined the absolute maximum and then just shipped it.

Re: Solar panels + cold = A potential problem

#123

Post by Aurornis » Sun, Sep 28, 2025, 3:25 PM UTC

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.

Most household solar systems do require permitting and inspections before you can turn it on. There are some exceptions in a few states for very small systems now. Ecoflow provides equipment for these small legal unpermitted installs.

More importantly, equipment shouldn’t self destruct in a dangerous fashion when pushed over the limit.

Re: Solar panels + cold = A potential problem

#124

Post by namibj » Sun, Sep 28, 2025, 3:25 PM UTC

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.

Your converter doesn't need to like the voltage, it just can't break from it. In fact, if it's the type that shorts the panels for curtailing, it should be happy to just run them at the highest voltage it's comfortable with, loosing a few percent generation during exceptionally cold days.

Re: Solar panels + cold = A potential problem

#125

Post by hyperhello » Sun, Sep 28, 2025, 3:27 PM UTC

immibis wrote: post #97

cornholio wrote: post #36

Earlier quoted context omitted.

> Adding "resilience" usually adds to the per-unit cost. In this case, the cost is much less than a dollar (say, a varistor that blows the existing fuse) and it prevents a catastrophic failure.

But they want you to have to buy another one.

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

Re: Solar panels + cold = A potential problem

#126

Post by cornstalks » Sun, Sep 28, 2025, 3:27 PM UTC

A lot of people here are saying things are mislabeled, but every single solar panel comes with a datasheet that shows its Voc and temperature coefficient.

Solar panel manufactures can’t give you a hard maximum on voltage because temperature will make that vary. Anyone who is buying solar panels without understanding the temperature coefficient shouldn’t be buying solar panels. It’s not hard to understand and there are hundreds of guides out there explaining it if you just search for terms on the datasheet.

Re: Solar panels + cold = A potential problem

#127

Post by rini17 » Sun, Sep 28, 2025, 3:27 PM UTC

bob1029 wrote: post #35

I never tried the solar charging on my ecoflow so this fragility surprises me a bit. I've been able to run laundry in a machine with a 1/2hp motor using the inverter side on multiple occasions. No smoke or funny smells. My 2200w generator would trip out the instant the spin cycle tried to start.

The solar panel with inverter does not have any inertia so it can survive power spikes more easily, can lower the voltage till it's over. The generator on the other hand has physical rotating parts that could be damaged by sudden torque asked by increased load. Of course it could be mitigated with additional "soft start" circuitry on the motor but that's usually not included. Not capacitor alone please, you risk more damage.

Re: Solar panels + cold = A potential problem

#128

Post by phyzome » Sun, Sep 28, 2025, 3:29 PM UTC

EcommerceFlow wrote: post #116

Cool article. The real solution to this is have huge arrays in the desert and move the energy north, which is 100% possible.

I don't think that addresses the thing that the article is actually about...

Re: Solar panels + cold = A potential problem

#129

Post by namibj » Sun, Sep 28, 2025, 3:31 PM UTC

TeMPOraL wrote: post #83

leoedin wrote: post #28

Earlier quoted context omitted.

In both examples given you can have 2 panels in series. So given that in almost all use cases, you can have 2 panels in series, they should just say “max 2 panels in series”. Simple. A good product hides complexity from the user with sane defaults and optional advanced configuration. This feels like the same problem.

There's hiding complexity, and then there's creating fake reality for people. As it is, panels are gonna produce variable power depending on the weather. Putting interoperability with third-party panels aside, to get the simplicity of "max 2 panels in series", they'd have to either cap the max power on the panel/generator link and dump the excess, or set the limit based on the worst case a customer is likely to encou…

The problem is that you run higher voltages with the same hardware if your in Alaska than if you're in Florida. Substantially so.

"Wasting" those 5~10% during severe winter conditions isn't worth splurging on the voltage converter.

Though then selling units that suggest to not run a few hundred volt strings before paralleling instead does sound bad, as the string doesn't need separate fuses rated to many volts DC.

Re: Solar panels + cold = A potential problem

#130

Post by nanomonkey » Sun, Sep 28, 2025, 3:32 PM UTC

emn13 wrote: post #57

xg15 wrote: post #46

Earlier quoted context omitted.

This feels a bit like the logic behind "do not put hamster in microwave" warning labels. I think if you work with electrical or electronic systems in practice, you learn pretty quickly to respect tolerances and that data sheets are a map, not the territory. Also, electrical installations are usually seen as a field that should be done by trained personnel, not arbitrary laymen home owners. So I think the appropriate…

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-...