Hi Nick,
I have a question that may not be entirely related to the main topic. Quite often, when browsing this forum, I read that it is not an official support channel, but rather a group of enthusiasts trying to help one another. However, from time to time a more serious question comes up, and then the argument is often made that since this is the official forum, we should only promote official solutions.
To be honest, that feels a bit contradictory to me. Either we are a group of enthusiasts who try to push the equipment to its limits, or we are an official body that is not allowed to do so. Everyone consistently points out that such actions are not covered by the manufacturer’s warranty — and I fully understand that. In this particular thread, no one even asked whether these actions would be covered by the warranty. Let’s be realistic: if we use equipment in a way that is not intended, we do so at our own risk.
That said, once the equipment has been purchased, it becomes the property of the buyer, and how it is used is ultimately up to them. I must admit, however, that I perceive your response as an official prohibition of such use.
So how should we understand this?
@alexpescaru
Alex, could you please explain why you are assuming from the outset that a short circuit will occur at the MPPT input? I have read many times on this forum that this is supposedly how MPPT operates — by shorting the PV panel input in order to find the maximum power point.
As it happens, my personal experience with Victron SmartSolar charge controllers contradicts that claim. If they actually behaved the way you describe, none of my installations — where I use them as buffer power supplies — would function properly. In practice, the situation appears to be quite the opposite. The MPPT increases current draw only until it satisfies the configured output settings. Once that point is reached, nothing further happens. The fuses I use on the input side have never tripped.
Since we are already discussing fuses, you are probably familiar with ultra-fast semiconductor protection fuses. In our standards, their characteristics are described as aR or gR. These types of fuses were specifically developed to protect sensitive electronics from damage.
If we are truly so concerned about a potential short circuit and its consequences, it is enough to connect ordinary incandescent light bulbs of the appropriate voltage in series in the main circuit — the classic filament type. If a short circuit occurs in the tested setup, the only effect will be that the protective bulb lights up. This is a time-honored technique, used by electronics engineers for decades when testing various kinds of equipment.
, that uses this site and may come across a topic like this. For that it is important we clearly spell out some of the risk so the official position is known.