Is it not possible to use a photovoltaic system with a battery autonomously?

Hello everyone,

Until recently, I assumed that with a photovoltaic system on the roof and a corresponding battery, you have a certain independence from the public power grid. My idea was that

[*]the photovoltaic system charges the battery
[*]the electricity for all devices in the house comes from the battery
[*]and the battery is connected to the public grid to feed in excess electricity or to recharge the battery when there is little sunshine

I recently heard from acquaintances that unfortunately you cannot use a photovoltaic system with a battery like that. The battery is indeed charged by the photovoltaic system, but if I want to use the electricity, I still have to take electricity from the public grid. At the same time, electricity from the battery is fed into the public grid, but I still depend completely on the energy supplier.

Is that really true? That would be completely absurd. That means that even with a fully charged battery, I would still experience every power outage (strangely at least once a year here)!?

No, the consumers in the house already use the electricity from the battery. Nevertheless, it is not possible without a grid connection, as the battery is not large enough and the photovoltaics produce too little in winter. In winter, the battery just sits empty and even requires maintenance charging from the public power grid.

Hmm, so it is just as I thought? Strange, supposedly the energy consultant from the municipal utilities had explained to my acquaintance that it wouldn't be possible...

Grund: Vollzitat entfernt

Theoretically yes. But then you need a system that also produces enough even in winter and possibly several days with little sunshine to cover several days’ consumption. Such a large system usually does not fit on a single-family house roof. And the battery would not only have to compensate for evening and night but also for the poor yield days. Economically senseless.

PS: Charging the battery from the public grid is doubly nonsense. Then you pay for the electricity plus conversion losses plus storage losses plus battery wear. The kWh easily costs more than twice as much.

In addition, many systems require the public grid in order for the battery and photovoltaics to actually supply power.

The grid dictates the oscillation. No power from the grid, no power from the photovoltaics or the battery.

However, there are also technologies that can supply power at least temporarily during a power outage (as long as the sun is shining or the battery can still deliver).

That's how it is. Many systems cannot operate without the grid simply because they cannot supply the necessary high short-circuit currents in the event of a fault.