How can the photovoltaic effect can be put to practical use in a commercial building?

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The Answer is
The photovoltaic effect can be put to practical use by supplying a commercial building with some or all of the electrical power it needs to operate. System sizes range from 2 kW to 1 mW and larger. The photovoltaic modules in the array produce direct current electricity when exposed to sunlight. Direct current from the modules supplies an inverter that converts the dc into alternating current (ac)synchronized with utility electricity.
The electrical energy produced by a photovoltaic system can be stored through the use of batteries that then supply the buildings electrical needs at night or on overcast days. A large enough system like this would not even need a utility supply of electricity.

How Can the Photovoltaic Effect Can Be Put to Practical