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 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.
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 will take to burn out for any given current and ambient temperature. You may find at 20C, it will not even burn out at a continuous load of 25A, and at 30A it might take 2 hours. So if you're buying a fuse to protect a sensitive downstream circuit, you need to take that into account and use a fuse that's nominally smaller than the load you're running.
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.
Got it, thanks for diving deeper!
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 sacrificial fuse or equivalent go first in these scenarios, whether it was a product aimed at professionals or not. It’s just dumb.
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.