Adding a normally-open relay and a voltmeter and a microcontroller should fix this. Relay won't close on startup unless the voltage is safe. Microcontroller will open the relay if the voltage gradually nears the limit. Should be solvable for <$5 in parts.
Dark start (when the batteries are flat w/o grid power) will be challenging. There will need to be a small battery to power the voltmeter and relay, or a high-voltage tolerant supply to power the microcontroller and relay temporarily. A 9V should likely be sufficient.
The standard answer for overvoltage protection is a crowbar circuit + fuse, and I think that's what I'd aim for rather than a relay. The problem with DIYing that is knowing the input capacitance of the Delta and finding out whether it has any other problems with its input being abruptly shorted.
It is because electronics work through magic so when you let the magic smoke out, they stop working.
It was almost a rite of passage to “let the smoke out” in that org. That job was actually great because as a software engineer I happily spent a lot of time with a fluke, a wrench, arm buried in the bowels of a vehicle fishing out sockets, etc. Writing the software was not the hardest part of those programs, but being one of the handful of folks that knew the entire electrical, cooling, mechanical, and software systems made us the most valuable folks on the program. We had to know all those things in order to write the software correctly.
“Did you know that computers actually run on magic smoke? Once the magic smoke comes out though, it stops working.”
This is proven by observation - the only thing you see charge is the smoke escaping.
https://www.researchgate.net/figure/Module-voltage-current-v...
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 illuminated in the morning. If you are close to the maximum voltage your MPPT charger can handle in normal circumstances, extreme cold can even damage things during the initial morning transient. You then have to do oddball things like use a crowbar system to prevent blowing up your MPPT system.
(see https://en.wikipedia.org/wiki/Maximum_power_point_tracking )
This is just like not upsizing wire gauge if you have a bunch that are loaded simultaneously buried together in a somewhat insulating wall. Without the burying under plaster, everything would be fine. But combine that with simultaneous loading during summer, and you fry/roast the PVC insulation.
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 sometimes 16A when it works in the cold.
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.
A 10A breaker breaks the circuit much faster than it takes for the wires to heat up, thus stopping the current flow.
Those things are normally built to handle a nominal 115 V assembly of panels. There's probably something on the manual about this, but when you put a giant label saying your device supports 150V, people are not going to read the manual.
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-rated MOSFETs? That's all too common in solid state relays from China.
Not seeing UL certification on this thing.
If we're going to have US protectionism against China, a good first step would be to require UL-type testing, carried out in the US, on all imported electrical devices that run on more than 12VDC or contain a battery chemistry capable of thermal runaway. Electrical safety is a solved problem if you can keep people from cheating.
[1] https://toshiba.semicon-storage.com/eu/semiconductor/design-...
Decades ago, when bipolar transistors were used, they were rated for 350 V, which is barely enough for 220 V + 10%.
When everybody started to design universal converters usable for 220/230/240 V, the ratings were increased to 400 V. The first power MOSFETs were also rated thus.
Then there were too many converters destroyed by random voltage spikes, so the standard ratings were increased to 500 V. That proved to still be not enough in many places over the world, so the ratings were increased to 600 V or 650 V, already many years ago, in order to make extremely unlikely the destruction of the transistors by voltage spikes much greater than the nominal mains voltage.
600 V or 650 V is used for converter topologies where the transistors see only the peak input voltage. For converter topologies that use fewer transistors, but those see peak-to-peak voltages, the rating of the transistors must be 1200 V.
For 650 V, gallium nitride FETs are the best available devices, while for 1200 V or higher voltages silicon carbide transistors are the best. Silicon transistors are the best only for ratings much lower than 100 V, but they may be preferred also at high voltages for being much cheaper.
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.
Yet so many people in this thread are so keen to blame the customer, it’s pure ego from them. “I’m too smart for that to happen, so it’s all their fault!” they sneer. Classic bad faith forum behaviour…
I need to actually look up why the extra flux increases voltage. Maybe it really doesn't but just moves the MPP to a higher voltage by having more current.
I don’t think this analogy works. The solar input works like Diesel or Gasoline in different temperature. It’s pretty unreasonable to assume the consumer knows when depending on temperature unless the explicitly state in the manual (I’m willing to bet good money majority of the people in US have never read their car manual either)
Diesel is blended differently for winter and summer in many countries. See this for instance https://www.crownoil.co.uk/guides/winter-blend-vs-summer-ble...
Around the skiing season, many automotive magazines will remind diesel drivers to buy “winter diesel” or use additives if e.g. driving up to the Alps or similar cold places.
It’s not so black and white :)
Sometimes they can be ok pedagogical tools, but they're easily misused as tools of persuasion.
This is a common pet peeve of mine, people not understanding how analogies are supposed to work and getting distracted by the differences. They’re supposed to work like a light filter placed over a lens, something will be highlighted and focus on that, don’t focus on the fact that “but all the colours are different now!”, the only purpose of using the light filter was to highlight a specific part of the image, the fact that it also coloured everything wrong temporarily is supposed to be ignored.
You know, just to use an analogy to explain analogies. Gotta be as meta as possible.
(certain fuel systems components will be degraded by high ethanol gasoline)
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.
"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.
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.
More importantly, equipment shouldn’t self destruct in a dangerous fashion when pushed over the limit.
Great, guys, how about you go ahead and multiply those two numbers for me, since you're the ones writing the fucking spec sheet? It's like if car battery manufacturers only specified a cranking amps number, and told you to figure out cold cranking amps yourself.
No time. Busy writing blog posts blaming customers.
What are you going to fill in for the third number, though? With an open-circuit voltage of 37.10V at 25°C and a coefficient of -0.35%/°C it can theoretically go up to 75V at absolute zero. And that open-circuit voltage is with an irradiance of 1000 W/m2, should we also account for the possibility of someone building a heliostat around it?
There's no one-size-fits-all number they could possibly quote. It'll always depend on the environment, because that's just how the physics work. The best you can do is provide a figure for the standardized testing environment and the relevant coefficients - which is exactly what they are doing.
42-48 is not a big enough range to give up over. My impulse is to arbitrarily pick -40 and say the normal max voltage is 45.5 degrees. Now it's nice and obvious that you can only hook up 3 to a 150 volt input, and you'll have a 9% margin of error left over. On that "first cold and sunny day" you'll output 120 volts instead of 160.
And no don't worry about a heliostat.
And no matter what happens, customer support should help the customer, not blame them.
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.
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 encounter. I.e. they're either gonna waste power, or gouge their customers for extra hardware. Neither of that makes sense for an ecological product sold to a price-conscious customer base :).
"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.
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 "resilience" usually adds to the per-unit cost. I think making a web page adds some cost too, but at least that can be amortised.
> And no matter what happens, customer support should help the customer, not blame them.
I think that's happening here: Making a web page to educate future customers seems like a really good idea. I wouldn't have thought that necessary until I saw it, but I'm always excited to learn something new.
The existing customers who did dumb should consider this a relatively cheap education in electronics; cheaper than a PHD at least!
Also, whether the company also gave them rebates or credits we don't know here, but telling "customer support" they "should help the customer" is also telling them they're not helping the customer, and you don't know that.
I don't think this is an official website of ecoflow.
Other than that I agree. I don't think asking for a bit of knowledge from the customers is a bad thing. A warning in the manual about safety factors should be enough.
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.
I have all sorts of electronics that say everything from 208V - 240V that all go in the wall, so I think all those numbers are probably close to each other in whatever a volt is.
I think if I'm worried about a limit of some kind, being within 5% of that limit seems like I might as well be over-limit if the commonly seen distribution I see in my house is greater than 15%
The margins are generally lower for higher power devices because the electronics are more expensive. Thankfully these electronics in general are becoming cheaper which is one reason why they’re ending up in the hands of people inexperienced with them.
Also try to tell someone they need an extra 30% in margin and often they'll think they’re being upsold.
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 computers with a switch on the back to choose between 220v and 110v.
Plugging something that takes 110v into my house breaks the thing, so I've learned to check.
But I don't have anything that's 208v that can't go into the house. So I think whatever the situation is with volts, within 15% is "basically the same", so coming within 15% of the rated limit, is probably just like exceeding the limit by 15%.
And so this is why I would not expect something at 146V to be under the safety limit of 150V.
> Also try to tell someone they need an extra 30% in margin and often they'll think they’re being upsold.
Where do you get 30%?
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 for the matter at hand, the margin mentioned is needed on the solar systems, this is where the inverters can get expensive, which is why it can look like an unnecessary upsell to people who’ve never blown a device before.
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.
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)
220[Vrms] * 1.414 = 311[Vp-p] btw. HOW!?
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.
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.
- Mr MBA
What's most likely though is that the fuse is also internal, and externally the unit will appear bricked.
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?
In fact, they can.
"Voc 37v @ 25*C"
Vs
"Voc 37v"
Edit: Isc is the same- max current.
E.g. choosing a random Jinko datasheet: https://jinkosolarcdn.shwebspace.com/uploads/JKM600-625N-66H...
V_OC is specified at both STC and NOTC, and the datasheet clearly states which environmental conditions accounted for in those test conditions.
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 reaction would be to remind people that they should hire an electrician to do the installation, if they don't have the necessary specialized knowledge themselves.
Though the lines are often blurred, because I guess most companies would like to sell directly to end customers, even if their product requires a professional to install.
Even IKEA does this. You can go in and buy an electric stove and oven, grab them from the warehouse and take them home with you right there. But it's a bit of an illusion: You're still supposed to call an electrician to actually connect the things.
You can do that by just reading the product page[1]. The delta pro, the equipment in question, looks like a plug-in appliance. It visually communicates that it is portable (by having a wheel and a handle) and by virtue of having a power lead connect to it it communicates that you can just plug it in. They further reinforce this by writing this: "Plug & Play home backup solution". "Easy installation with completely pre-wired Plug & play home backup solution" "The solution provides a convenient home battery system without rewiring or running dangerous extension cables through your home." "Plug directly into an AC wall outlet and make sure that the wall output current is more than 15A."
And on top of that the manual[2] makes no mention of needing an electrician.
In contrast an IKEA electric oven's product page[3] states this: "No plug is included. Installation to be carried out by a qualified installer." and then the manual[4] states "Installation, including water supply (if any) and electrical connections, and repairs must be carried out by a qualified technician."
But of course nobody reads the manual. The big difference is that one comes with a plug while the other doesn't.
1: https://us.ecoflow.com/products/delta-pro-portable-power-sta...
2: https://websiteoss.ecoflow.com/cms/upload/2022/10/12/1312845...
3: https://www.ikea.com/gb/en/p/mataelskare-forced-air-oven-ike...
4: https://www.ikea.com/in/en/manuals/matalskare-forced-air-ove...
This world is amazing anything runs at all. The slightest addition of complexity is causing everything to fail now.
Modern computers are less reliable than ever, some companies have decided to REMOVE the pinhole bios reset (that has been around for 30 years) at the same time as things are buggier now and dont boot again until you physically unplug the bios battery deep inside and hard to get to.
It works! OK, stop touching it. We don't want to break it.
Whether or not the company in this case shares some or most of the blame with novice users - the analogy is not a great one.
https://interestingengineering.com/videos/1950s-reanimating-...
Yeah, this sounds very much like "you're holding it wrong".
That is the issue is with the wrong labeling of things that are being plugged into this vendor's device, not the vendor's own labeling.
I agree the labeling is an issue here, but the solution must come from the wider industry or regulatory bodies; the alternative is for vendors to switch to their own pseudo-units to internalize the math, which would not be good for customers either - think "ACME Generator2000 accepts up to 4 Power Units of input; each ACME SuperEco Panel supplies 1 Power Unit, or 1.5 Power Units if you're in Canada...".
Saving users from having to do a little thinking to not brick their device is a tried-and-true excuse for vendor lock-in in our industry :).
Completely unhelpful to those that need the info.
Nobody seems to remember a bunch of companies receiving rather large fines for pulling known bull-crap "may contain sesame."
The label on the modules themselves tend to also provide these ratings at STC, e.g. this label from Jinko specifies the Open circuit voltage and also summarizes the conditions assumed for STC:
https://image.made-in-china.com/202f0j00LURcYuatWIqH/Jinko-M...
While I agree that the label could also add the temperature coefficient, I'm not sure if it's reasonable to expect that specialist electrical equipment details all of its operating parameters on an attached label without the expectation of consulting a datasheet or manual. For specific products that primarily target non-specialised consumers however, a different labelling approach may be warranted.
And even for amps where you see that 80% rule, that's for keeping the load smaller than the supply. Solar panels aren't a load and don't work that way.
Typical house wiring is required to handle 600v due to voltage transients and wear and tear.
So any component rated to 240V dc will fail immediately on AC, and even 400-500V DC is not a good idea.
I guess there is a reason there is a whole category of engineers for this kind of thing.
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 battery, or whatever else.
This is like how AA batteries have a nominal voltage of 1.5V but the actual open circuit voltage is 0.9V~1.65V depending on charge level, temperature, etc. If you connect an AA to something that’ll explode at a voltage of 1.55V, that’s on you.
Similarly if you buy a 470 ohm resistor, you will find in on the data sheet that’s usually at 20°C. To know what it’ll be at any other temperature, you’ll need to use the temperature coefficient to calculate it.
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 sacrificial fuse or equivalent go first in these scenarios, whether it was a product aimed at professionals or not. It’s just dumb.
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.
Essentially the "nominal" behaviour is not the actual behaviour, it's just a quick way of summarising the characteristics in a way that someone familiar with the class of item will be able to understand what they're buying. Another similar situation is timber sizing, where a 2" by 4" is actually 1.5" x 3.5".
In the case of electronic components, the actual behaviour will be either documented in a datasheet or just common knowledge in the industry. For example if you're buying a standard li-ion battery with no active circuitry, you'll often find the datasheet quite lacking in details because you are expected to just know the characteristics of the li-ion chemistry provided the basic parameters are provided.
So say, the input is rated for 150V, spec the components to sustain 180V, and trigger the MOSFETs to disconnect the panels at > 160V.
And maybe also add a big ass buffer capacitor, that can be used to soak up a bit more energy in the case of an inrush spike before the MOSFETs actually disconnect.
DC starts getting really nasty to deal with somewhere between 36-52v, with 150v of panels not being something joe-blow should be able to buy on amazon. Designing these systems to be safe is difficult.
Lesson learned: don't skimp on Li-ion battery packs!
Also, I have a question about this article. Don't EcoFlow battery packs have a circuit that checks the incoming voltage and automatically shuts off charging if the voltage is too high? I would also expect a loud alert.
`Solar Panels + Cold = A Potential Problem`
[1] https://theconversation.com/conclave-the-chemistry-behind-th...
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.
I wonder if such a capacitor could even be retrofitted.
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.
There are 'home batteries' that store power for practical reasons up to a day, maybe two. They are useful for sunny/cloudy conditions to maximize the amount of power locally consumed. But battery storage and retrieval isn't free and so far - at least, for my installation - this does not make economic sense. But another factor of two in price drop for my preferred chemistry and it definitely would make sense and then I would probably install about 20KWh worth of capacity. The trick then becomes to balance power sent to the grid and sent to the battery so that you maximize the utility of the grid in order not to wear out the battery prematurely. That means cycling the battery between 70 and 90% state-of-charge for Lithium-Ion. I'd much rather have Lithium Titanate so that is what I'll be holding out for, they are already available, but still too expensive. But they're much safer and have far better charge/discharge curves and life-span.
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 marketing, and it'd make this article manipulative, false blaming of the customer.
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 have come up with, not a guaranteed theoretical maximum.
In fact considering there is no theoretical maximum, it would be downright negligent not to have overvoltage protection
The open-circuit voltage depends mostly on the structure of the solar cells and on the temperature. It has only a very weak (logarithmic) dependence on the amount of light received.
The voltage that you measure at the output depends on the open-circuit voltage, on the amount of light received and on the amount of current that you draw from the panel.
The maximum open circuit voltage for a solar cell is easy to estimate, because it happens at the minimum temperature for which it is designed and the maximum solar illumination. It can be exceeded only using a light concentrator that projects on the panel light collected from a much greater area.
Of course if you want to extract maximum power you have to balance the higher worth of the current you take against the loss of current to the diode forward conduction.
Temperature Coefficient Specifications
TKPower -(0.39±0.02)%/k
TKVoltage -(0.33±0.03)%/k
TKCurrent +(0.06±0.015)%/k
STC ("standard testing conditions" for solar panels) is 25C so if it's freezing 0C you have 25 multiplied by 0.33 Volt = 8.25 Volt more than STC in open circuit situation.
Unfortunately inverter manufacturers seldom document how many Volt will destroy the MPPT and up to how many Volt the MPPT will safely turn off by itself before breaking.
Solar panels are current sources that waste their power into a long string of silicon PIN diodes that eventually reach their forward voltage and begin to eat up all that juicy current. You can just take the current and keep the voltage as low as you want, just make sure to take all the current or it's voltage will rise to let the diodes take the current you aren't using.
I think this is where the confusion arises - what do you mean by ideal conditions? Ideal conditions for solar generation are not necessarily at the same time as the highest voltage operating conditions. VoC tends to be specified at Standard Test Conditions which has light-levels representative of a sunny day (1000 W/m2) and a cell temperature (not ambient) of 25 degrees C, which is already a lot cooler than most panels would typically be at that level of irradiance. So really, the label is already specifying a voltage higher than what you would typically experience during times of max generation.
However, the max voltage could exceed this rating at times when there are cold ambient temperatures with enough light for the module to function, but not enough sun to meaningfully heat the cells. So in this scenario you may have maximum voltage, but you're far from maximum power nor at 'ideal conditions'.
https://www.sciencedirect.com/science/article/pii/S258900422...
https://www.pv-magazine.com/2025/01/13/daytime-radiative-coo...
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..?
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
If a panel can hold down the voltage of others, their device should be able to do the same.
Sounds like a corner case their software can't handle. Even so, the hardware should not go up in smoke.
Back when Home Power magazine started up, the panels were super expensive, and squeezing out every watt was important. Since high temperatures decrease voltage and output, keeping the panels cool (while baking in the sun!) was top-of-mind for every installation. And right along with learning that critical consideration, everyone also learned the caveat that in the bitter cold, that very same phenomenon means they can produce significantly more. Temperature coefficient was simply something "everyone knew".
Now they're so cheap nobody cares. The magazine shut down because "alternative power" and EVs aren't exactly alternative anymore, you can buy one off the dealer's lot, it's nuts. And the panels are crazy cheap now. If you lose 10% because the panels are hot, it's likely cheaper to just buy 10% more panels, than to redesign your support brackets to allow better airflow. But nobody highlights the phenomenon behind the efficiency loss.
"Everybody knew" that the ratings on the panel are at Standard Test Conditions: 25°C and 1000W/m². That's almost never the conditions in the real world, but it establishes a legal baseline whereby panels can be compared apples-to-apples and advertising kept honest (if anyone cared), but deviate from STC and output will go down, or up. Again, ask today's consumer what the ratings on the label mean, and most of 'em have never heard of STC nor could define how the nameplate wattage is just one point on a curve.
Is this the panel manufacturer's fault? They're labeling things precisely the same as they've labeled them for 40-plus years. (Perhaps there's even more data on the panel label now, as Vmp and Imp are typically specified now, and they weren't always universal.)
Edit to add: The label doesn't typically specify the temperature coefficient, but for every panel I've checked, it is in the datasheet. But who reads datasheets?
Is it the inverter manufacturer's fault? They're labeling things precisely the same as they've labeled them for 40-plus years. The input max is a hard limit where the silicon can take no more, and there's a certain amount of headroom required between that and the panels' max, after compensating for temperature coefficient. Of course you calculate your panel voltage for your local conditions before comparing it to the inverter input, duh!
Everyone knows that! Except now they don't.
I think one of the main reasons why installers tend to overprovision voltage wise is that they count on the inverters switching off the whole string every now and then versus being able to make more power without a lot of additional wiring under normal conditions. The net effect of that is positive.
Low quality inverters (the ones without the ability to disconnect the HV side autonomously) should be avoided like the plague anyway, those are simply unsafe and as far as I am concerned should not be allowed for re-sale at all.
My own system can make 17KW on a very good day in March at 1 pm or so, but normally it is closer to 12KW even in the summer. So those peaks are actually substantially over the normal output. Over a given day the average is about 5 KW or so from sunrise to sundown, and those first and last hours hardly contribute.
Here's one in Tromsø Norway, well north of the Arctic Circle.
https://cleantechnica.com/2025/09/27/bifacial-rooftop-vertic...
But then it goes all Black Mirror, with manufacturers restricting solar-panel operation to approved devices only, and UIDs being used to enhance shareholder value through recurring subscription revenue.
(Technically the current source in question is _within_ the diode's junction capacitance.)
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.
Ok, that is a very bad answer. Diesel fuel contains more amounts of energy per drop as gasoline, but that doesn't mean engine damage will result. Diesel fuel will not damage an engine if you were stupid enough to get it wrong at the pump. It will simply refuse to cycle until the diesel fuel is pumped out and the correct fuel is pumped in.
The other way around is possible. You can fill a diesel tank with gasoline. Whether it destroys the engine or not depends on how much gasoline you put in. A gallon or two that is then diluted by filling the rest of the tank with diesel is not likely to cause any lasting damage. If you fill a tank 3/4 of the way with gasoline and try running it in a diesel you are probably going to need a new engine.
So yeah, the analogy is not good. Slightly exceeding the rated voltage and breaking the whole thing is usually not the same as putting a little gasoline in your diesel tank.
64-202 Voltage of solar photovoltaic systems (see Appendix B)
1) The maximum photovoltaic source and output circuit voltage shall be the rated open-circuit voltage of the photovoltaic power source multiplied by 125%.
2) Notwithstanding Subrule 1), the maximum photovoltaic source and output circuit voltage shall be permitted to be calculated using a) the rated open-circuit voltage of the photovoltaic power source; b) the difference between 25 °C and the lowest expected daily minimum temperature; and c) the voltage temperature coefficient as specified by the manufacturer.
I think what Delta needs to do here is accept that the standards mean all Solar will be sold this way and appropriately oversize the inverter so that it can cope with -10C sunny days. Yes its annoying for them but the reality is devices sold to people who don't know how all this works need to compensate for lack of expert knowledge in its user base.
It is still well within the 'engineering reserve'. Solar panels produce the most power in mid March, when they are cooled very well by the ambient air but the sun is already lining up nicely with the panels at mid-day. But those conditions are pretty rare, and most inverters will handle this gracefully by simply dumping some of the excess power as heat - or in the better ones, by simply chopping the input voltage at a high frequency. This allows for very fine control over the average power and will help to keep the voltage under the isolation break down voltage (which usually is a very large factor over the voltages that you see in practice).
My own system is 50 panels, 1000V maximum on panels that nominally produce up to 100V, so I never have more than 8 of them in series. That leaves 200V to play with and I've never seen it get close to that 1000V. The inverters are easily capable of dealing with this and if the strings were to ever exceed 1000V then the inverters would simply disconnect those strings with their internal disconnect relays.
So, in closing: don't run your system 'on the limit' or rare conditions will push it over the limit. But even if you do: inverters are fairly bullet proof nowadays and if you over-volt the input the vast majority of the ones that you can normally buy are going to just switch off and move to an error state that will require you to power them down before they will be usable again.
This is what MPPT controllers do, as this maximum power setpoint will change as environmental conditions change.
Covered in snow over the winter and generate little power November-February but rest of the year we have fine power output, with peaks May-July (obviously).
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 power - ie safe - points. I=0 is the usual one, but V=0 (ie short circuit) is equally safe for solar panels.
So this hypothetical inverter would operate between one of the safe points and the max power point.
Obviously whilst installing the system and humans unplugging wires, the V=0, huge current safe point is impractical. But that's why you have breakers.
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.
BobbyTables2•4mo ago
Sure, diode forward voltages change a little but seems like something else is going on…
AgentK20•4mo ago
mindslight•4mo ago
bobjordan•4mo ago
objectcode•4mo ago
Let's say with certain current there is 0.687V. If two diodes are connected in series i.e. (point a) → diode 1 → diode 2 → (point b), and each has a 0.687V voltage across, that's 0.687 + 0.687 = 1.374 V between point b and point a.
For the solar diodes, the "current" depends on how "strong" the sun is. If at a certain "current", across each diode is 0.687V, you'll need 216 diodes in series (between two points) to get 0.687×216≈148.4 V.
If there is 0.002 V increase per diode per 1°C decrease, with 216 diodes, that's a 0.002×216=0.432V increase per °C decrease, so with a 4°C decrease it exceeds the MPPT's limit.
Another thing about solar that differs from how diodes are "normally" used in circuits is that the "true" voltage depends on the max current achievable with the how bright the sun is right now, instead of the "true" current. When the "true" current is 0 A, the voltage across each diode might be 0.687 V. When the "true" current is 0.5 A, maybe 0.65 V. 1A, maybe 0.6V. 2A, maybe 0.3V. Try to get more "true" current, the "true" voltage drops. Try to get more "true" voltage, the "true" current drops. Power is voltage × current so when full speed charging, the MPPT uses an algorithm to find the (possibly) best minimum (not maximum) input voltage based on the temperature etc and trades voltage for current at the output. If there is no minimum input voltage restriction, solar will follow the battery's terminal voltage + cable drop instead, and instead of something like 111V, there could for example be a ~4x less powerful 25.5V (if the battery is a "24 V") with just 10% more current.
At the MPPTed min input voltage for full speed charging, maybe 111V, all might seem well even with low temperatures, but when the battery is full and there is approximately nothing using electricity from solar, the real input current will be ~0 A, so there will no voltage "sag", so the solar will realize the full voltage corresponding to the temperature and the illumination, potentially >150 V...
namibj•4mo ago