It is possible to create an autonomous power supply system with solar panels of varying complexity. The simplest system has a low voltage DC output (usually 12 or 24V). Such systems are used to ensure the operation of lighting and a small DC load in the house – radio, TV, laptop, tape recorder, etc. You can use a variety of car accessories, up to refrigerators. It should be noted that this requires the laying of separate DC wiring with special sockets and plugs that exclude incorrect connection polarity. When connecting luminaires with DC lamps, you must also observe the polarity and ensure that when replacing the lamps, they have the same polarity as those previously used. Otherwise, your consumers may fail.
A typical diagram of such a system is shown in the figure on the right. Typically, such systems are used if the maximum distance from the battery to the farthest connected load does not exceed 10-15 m, and its power is no more than 100W. In this case, it is necessary to ensure that the voltage drop with all switched on consumers at the farthest point is within the permissible range (usually no more than 10%). For the correct choice of the wire cross-section, you can use the reference information on the selection of the wire cross-section based on the permissible voltage drop in the wiring section.
If your load exceeds the recommended maximum values, or your electrical consumers are at a considerable distance from the battery, you must add an inverter (low voltage DC / DC converter from batteries to 220 VAC) to the system. In this case, you can supply almost any household load with a total power not exceeding the power of the inverter. The power supply system of an autonomous house with an AC output based on a photovoltaic solar battery in this consists of practically the same components as in the previous case, plus an inverter, i.e.
To ensure a reliable power supply, a backup power supply is required (not shown in the figure). A small (2-6 kW) gasoline or diesel electric generator can be used as such a source. The introduction of such a backup source of electricity dramatically reduces the cost of a solar battery due to the absence of the need to rely on it for the worst possible conditions (several days without the sun, operation in winter, etc.)
In this case, a charger is also introduced into the system for fast charging (within several hours) of AB from a liquid-fuel electric generator. It is possible to use an uninterruptible power supply unit in which the battery charging function is already built-in.