I do have a solar system with a batterysystem installed. The guarantee from the company is 20 years, but with maintenance periods of 5 years. The gurantee is for >80% of battery energy after 20 years.
However, part of the contract is the replacment of battery packs, if they show lower capacity than expected. Usually this is after 10 years.
The battery usually loads during the day and powers the complete house during the dark hours. It also has a module that takes over as soon as external power is down.
This is all very nice, but there are many issues to keep in mind. The most important is the size and that depends completely on what power consumption your house has. This will tell you what amount of solar panels you really need and of what size the battery must be.
If your battery is too small you will not have much time before it shuts down, if it is too big you invest too much money and get no return of investment. So start with some investigation of your current power consumption, ideally for several month and different times of the year. For example during the summer you don’t need heating, but probably air conditioning, during the winter the opposite. So how much do these systems need.
Depending on the part of the world where you are there are different systems for energy and different requirements for integrating your own energy generation.
So what is needed in such a system. Solar panels produce DC power, your house needs AC power. The most important module here is a electrical inverter, that converts the DC into AC power and connects to your house and the battery. How this is done depends on many technical factors and the type of hardware, including the battery types.
On top of the solar panels and the battery is a module between your battery and the external power connection. In case of a failure the cable from the outside needs to be disconnected automatically (within some subseconds) to avoid your internal system to send power back to the outside world. This would be extremely dangerous for the technicians working on the street, because they expect to have no power on the cable and now you stream your energy back. This kind of module is something that your electrician needs to integrate, make sure you find someone who clearly knows what he is doing.
Nobody here can give you concrete numbers, that is impossible. You really need to talk to companies that build such systems and let them calculate your needs. If you are not able to follow all the tech talk try to find some person you trust and has the knowledge and let them join the talks.
No idea if this helps you in any way, but I thought it might be a small start.
