A power supply that is as self-sufficient as possible does not work without solar power storage sytem. Retrofitting therefore also makes sense for older PV systems.
Good for the climate: That's why it's worth retrofitting a solar power storage system for photovoltaics.
The solar battery storage system stores surplus electricity so that you can use it later. In combination with a PV system, you can also provide your house with solar power at night or when the sun barely shines.
Economics aside, it's always a smart thing to add a solar storage system to your PV. With a battery storage unit, you'll be less dependent on your energy supplier, electricity price increases will affect you much less, and your personal CO2 footprint will be smaller. An 8 kilowatt-hour (kWh) battery storage unit in an average single-family home can save the environment about 12.5 tons of CO2 over its lifetime.
But buying a solar storage system is often worth it from an economic perspective as well. Over the years, the feed-in tariff for self-generated solar electricity has fallen to the point where it is now lower than the price offered. Therefore, it is no longer possible to make money in this way with photovoltaic systems. For this reason, the trend is also to self-consume as much as possible. Solar power storage systems help to achieve this goal. In the absence of storage, the share of electricity self-consumption is about 30%. With electricity storage, a share of up to 80% is possible.
When it comes to battery storage systems, there are AC battery systems and DC battery systems. The abbreviation AC stands for "alternating current" and DC means "direct current". Basically, both solar storage systems are suitable for photovoltaic systems. However, there are differences. For newly installed solar power systems, battery storage systems with DC connection are increasingly used because they are said to be more effective. They are also usually less expensive to install. However, DC storage systems are connected directly behind the photovoltaic modules, i.e. before the inverter. If this system is to be used for retrofitting, the existing inverter must be replaced. In addition, the storage capacity must be adapted to the power of the photovoltaic system.
AC battery systems are therefore far more suitable for storage retrofitting because they are connected behind the inverter. Equipped with the right battery inverter, the power size of the PV system is then rather insignificant. Thus, AC systems are easier to integrate into existing photovoltaic systems and into the household grid. In addition, small combined heat and power plants or small wind turbines can be integrated into an AC system without any problems. This is advantageous, for example, for achieving the greatest possible energy self-sufficiency.
The size of the solar storage solutions is of course individually different. Decisive factors are the annual demand for electricity and the output of the existing photovoltaic system. But also the motivation why the storage should be installed plays a role. If you are mainly concerned with the economic efficiency of your electricity production and storage, then you should calculate the storage capacity as follows: for 1,000 kilowatt hours of annual electricity consumption, one kilowatt hour of usable capacity for the electricity storage.
This is only a guideline, because in principle, the smaller the solar storage system is designed, the more economical it is. Therefore, in any case, let the expert calculate exactly. If, however, the self-sufficient supply with electricity is in the foreground, the electricity storage can be dimensioned considerably larger, regardless of the costs. For a small single-family home with an annual electricity consumption of 4,000 kilowatt hours, the decision for a system with a net capacity of 4 kilowatt hours is just right. The gains in self-sufficiency from a larger design are rather marginal and out of proportion to the higher costs.
A compact solar power storage unit is often no larger than a refrigerator with freezer compartments or than a gas boiler. Depending on the manufacturer, the home battery system are also suitable for hanging on the wall, For example, BLSBATT solar wall battery, Tesla Powerwall. Of course, there are also solar battery storage that require more space.
The place of installation should be dry, frost-free and ventilated. Make sure that the ambient temperature is between 15 and 25 degrees Celsius. Ideal locations are the basement and the utility room. As for the weight, of course, there are also big differences. The batteries for a 5 kWh batetry storage unit alone already weigh around 50 kilos, i.e. without the housing and battery management system.
Lithium ion solar batteries have won out over lead batteries. They are clearly superior to lead batteries in terms of efficiency, charge cycles and life expectancy. Lead batteries achieve 300 to 2000 full charge cycles and live a maximum of 5 to 10 years. Usable capacity ranges from 60 to 80 percent. Lithium solar power storage, on the other hand, achieves approximately 5,000 to 7,000 full charge cycles. The service life is up to 20 years. Usable capacity ranges from 80 to 100 %.