When installing a photovoltaic system, have you ever wondered whether you need to install a battery? There are two types of home PV systems, one is off-grid, the other is on-grid.
In simple terms, off-grid is to store the electricity generated by a photovoltaic system in a battery, which is then converted by an inverter to power household appliances. on-grid means that it is connected to the mains electricity, directly converted into the voltage requirements of the national grid through the inverter, and prioritized for household use, and the surplus electricity is sold to the state.
Advantages and disadvantages of off-grid PV systems
1. The great advantage of an off-grid PV system with storage is that it can be installed almost anywhere that is off the grid but constantly in need of electricity, such as a mountain hut or a boat.
2. It can also be used as emergency power generation equipment in areas with frequent power outages.
1. Batteries account for 30-50 percent cost. And the service life of the battery is generally 3-5 years, after that it have to be replaced, which increases the use cost. In Germany, for example, the cost of purchasing a PV system for a typical single-family home is currently around €8,500 (average 5 kW P system). A 5 kW P system with a 5 kWh battery costs between 14,000 and 16,000 euros.
2. If there is not enough generation and storage to get the necessary power from the grid, your house will be left without power.
Advantages and disadvantages of on-grid PV systems
1. It does not need to use batteries, saving costs.
2. When solar system generates more electricity than your appliances can use, the excess is sent to the public grid, where you not only get paid for it, but also contribute to the energy transition.
If you have a 10-kilowatt photovoltaic system installed in your home, the EEG 2023 amendment allows you to get 8.6 euro cents per kilowatt-hour for excess electricity that goes into the public grid. Large systems also offer higher rates of return than before. Up to 40 kW (including 40 kW), raised to 7.50 euro cents per KWH. The portion up to 750 KWH still earns 6.20 euro cents per KWH. In an average household, about 35 percent, or 65 percent, of the electricity generated is put into the grid and paid for. A rough estimate is that a home PV power station pays for itself in about 10 years.
Photovoltaic system can't work when the public grid is cut off. However, if the on-grid inverter is replaced by an intelligent micro-grid inverter (on-grid and off-grid hybrid inverter), the power station can operate normally.
At present, many households choose to install on-grid photovoltaic systems. But this is not suitable for all families, it depends on specific circumstances and also needs to meet local policies.