Comment by margalabargala
8 hours ago
That doesn't make sense to me. On a cheap RV inverter maybe, but on solar for a house? The inverters should be rated to continuously output whatever the panel is generating. It shouldn't care whether the 2kW is going back on the grid or into your water kettle, it should be doing that all day every day.
Typical hybrid inverters have an output rating around half the theoretical max input of the panels. This is due to theoretical max of panel input being very rare or even impossible in normal earth conditions, the presence of an attached battery to soak up part of the input, and the general cost benefit trade off of solar equipment (more throughput means more heat, means bigger heatsinks, means heavier and more expensive).
You can definitely get equipment that can do symmetrical input/output, but if you actually model out the supply and demand curves on the system it's not usually going to be worth the extra up front expense since peak input is a small portion of the day and that extra hardware will mostly sit idle.
For that matter people often design systems where peak input can't even be accepted by the inverter and the extra power is just wasted, because it's more valuable to have a steady input over a long period than to maximize the daily peak.
Yes, my grid-tied system is like this. The panels are ~410W and each one has a microinverter with ~390W maximum or something. The more expensive inverters were not worth capturing the peak. You’re better off putting that money into more panels.
In the US, most home solar installations do not have a in-home battery. It is not uncommon for rooftop solar to be producing >90% of nominal max, for hours at a time.
I know multiple people with solar and have discussed their specs with them extensively. Zero of them have inverters or microinverters sized below the theoretical max of their array.
Are you thinking of a purely off-grid setup without actually saying so?
Nope but in a different market so makes sense, those are probably pure grid tie inverters, which I don't have a lot of experience with because it's not commonly used here. I do see the EG4 hybrid has a similar ratio (we have the same tech here under the Luxpowertek brand).
Even without a battery people usually choose hybrid, which can function on and off grid.
Also to be honest I'm mostly looking at larger inverters so maybe that colors it. Not many users here need 24,000 watts continuous outside a commercial context, for instance, so an inverter with that as an input but 12,000 watts continuous AC output doesn't seem weird since part of the 24,000 watts DC can be sent to the battery.
3 replies →