Stand-alone inverters

There has been a considerable increase in the number of requests for inverters to be installed on photovoltaic solar plants which supply power to isolated users.

The principal reason is the users' desire to maintain the same level of comfort they have in their main residence (in the case of mountain chalets).

Square wave inverters

• simple technology
• risk of generating odd harmonics --> problems
• no regulation of outgoing voltage (varies with charge and incoming voltage)

Modified sine wave inverter

• better efficiency
• fewer harmonics than square wave inverters
• precise regulation of voltage
• appropriate for powering many devices (televisions, engines, table saws)

Sine wave inverter

• technique similar to inverters used for connecting to grid, but with simpler circuits and no protection from or synchronisation with grid
• Elevated efficiency, suitable for practically every type of user.

Important elements for choice

• Precision of outgoing voltage (% compared to 230 Vac)
• power acceleration --> very important for certain electrical devices (refrigerators, pumps)
• efficiency --> it is very important to check efficiency when power is low
• consumption and stand-by precision (automatic partial switch-off in absence of charge)