Photovoltaic Solar Systems Types & Germany practice

The most developed method to generate electricity from renewable energy sources is photovoltaic solar systems.
There are two types of photovoltaic systems:
(1) Stand Alone System: at this type the total electricity generated from the solar photovoltaic panels should meet the demand at all times during the day. But this is impossible since we haven’t sun at the nigh, So PV systems should be supported by either two means:
First: by additional electricity power source like wind turbine, diesel generator or cogeneration engine. This type is called photovoltaic stand alone hybrid system.
Second: by a storage systems (batteries). This type is called photovoltaic stand alone with storage system.
(2) Grid connected system: at this system PV panels work in parallel with the public electricity grid in the condition that in case of grid electricity outage, PV panels will automatically switched of until the electricity of the public grid is returned back.
Germany Experience:
Germany consider as a leading country in using PV systems. Most of PV systems present in Germany are of the type grid connected system which present all over residential, commercial and industrial sectors due to the premium feed-in tariff  as all the energy generated is fed to the public electricity grid . Germany government predicts that after 30 year one third of electricity power supply will be generated from photovoltaic systems.
We hope that all countries will do like Germany government does in order to meet the increasing demand of electricity.