You check the app late in the evening or at night. The battery still shows 30 or 40 percent, the house is using very little, and yet the grid is supplying it. Nothing looks wrong with the battery, so why is it not being used?

Your inverter needs power to run itself. That consumption stays roughly the same whether it delivers 100 watts or 3 kilowatts.

So when your house is only drawing a very small amount, running the inverter costs a large share of what it delivers. Below a certain output it is better to leave the battery alone and let the grid supply those few watts. The inverter decides this for itself.

For the Sofar HYD series, the manufacturer states a standby consumption below 15 W and a battery charge and discharge efficiency of 97.8%. That efficiency applies at normal load. At a very low output the fixed consumption of the inverter stays the same while the delivered power shrinks, so the share lost to running the inverter grows quickly.

The amounts involved are small. On an installation we measured for this, the grid supplied roughly 4.7 kWh this way across two months. That is a few cents per week.

What is described above is normal. Let us know if you see something different:

If you can give us the dates and roughly the times, we can look at those exact moments. Your quarter-hourly Fluvius data alongside our own measurements is the fastest way to get to the bottom of it.

Still not clear? Get in touch through our contact page.