Generation of electricity from solar energy is called photovoltaic. In solar cells - usually made of silicon - positive and negative carriers are released, when they are irradiated with light (photo effect) So they produce direct current, which can directly drive motors or recharge batteries. If solar power should be used for normal operation of loads with 230 volts AC or fed into the public grid (sold), inverters are needed to generate AC power.
You need no permission to install a (private) solar system on your own roof, except for special architectural solutions or listed buildings. We recommend prior to check with your building department the existing rules. Check the statics of the roof: We advise an evaluation by a structural engineer of an impact of an additional load of up to 20kg/qm.
The advantages of photovoltaics are a clean, ecological power generation and the ability to supply consumers from the power grid (stand-alone solution), eg in the weekend house, in gardens and parks, or for lighting bus shelters.
PV systems are very durable even under extreme conditions. PV modules can last for decades under extreme conditions such as storms or salt water and they are used especially due to their economy as grid-connected plants or in combination as grid-connected and net metering.