Thephotovoltaic systems,on a descriptive level, they can be divided into three large families; we thus have facilitiesgrid connect(plants directly connected to the electricity distribution network), independent systems(not connected to any distribution network because they supply energy directly to the house) and hybrid systems, which remain connected to the distribution network but use solar energy mainly through accumulators.
Other names to indicate the type ofindependent photovoltaic system:
off grid photovoltaic system,stand alone photovoltaic system, stand alone photovoltaic system.
Hybrid photovoltaic system
In the last year, in Italy, thephotovoltaic systemshybridsfor home use. Users who have chosen a photovoltaic system with an inverter integrated withaccumulatorhave the ability to store the energy produced and not consumed instantly in order to use it at night. With hybrid systems only the energy surplus is forwarded to the electricity grid while the family has the opportunity to make the most of their photovoltaic system.
Aindependent photovoltaic system, also saidstand alone photovoltaic, it is very useful for those electrical users isolated from the national electricity grid; in common use aindependent photovoltaic systemit can be useful in a mountain cabin, on boats, on campers and in all those particular circumstances where a connection to the electricity grid is not possible.
What does an independent photovoltaic system consist of?
A stand alone photovoltaic system is usually composed of classic photovoltaic modules, storage batteries, a charge controller, an inverter and sometimes a management unit.
- Photovoltaic modules
Technically called "photovoltaic field". This is the surface made up of solar cells designed to capture the rays for electrical production. The photovoltaic field must be properly arranged so as to receive maximum solar exposure. In some cases, thephotovoltaic headit can be equipped with a solar tracker, a technology that adjusts the position of the panel making it always favorable to the sun.
- Storage battery
Similarly to what was said for thehybrid photovoltaic systems, also anindependent solar systemit needs accumulators for energy storage. The accumulator is usually made up of one or more rechargeable batteries connected in series or parallel to preserve the electric charge generated by the solar cells. The accumulators allow a deferred use of the electricity produced by the electrical appliances.
- Control unit
A rear-type control unit can optimize the use of self-produced clean energy and increase the lifespan of the accumulators. The control units are particularly useful in case of severalstand alone systems:if in addition tostand-alone photovoltaic system there is also a small device domestic wind off grid, the control unit allows you to automatically switch the energy between the two renewables passing from one or the other source or obtaining energy from storage batteries.
- Charge controller
The charge controller has a role that can be understood from its name: it is responsible for stabilizing the electricity collected and managing it within the system according to the various verifiable situations (if the user consumes the energy produced instantly, he sends the surplus into accumulator, if during the operation of the panel the user needs more energy than the solar panel is supplying instantly, then it takes some from the batteries ... and so on).
The inverter is essential in any type ofphotovoltaic system. It is a DC / AC converter and its role is to convert the direct voltage output from the solar panel (usually 12 or 24/48 volts) into alternating voltage, higher, generally 110 or 230 volts for systems with a total power. contained or at 400 volts in the case of systems with power exceeding 5 kW.