What is an inverter, and why would you want one in your renewable energy system? This is a reasonable question. Some small renewable energy systems don’t need an inverter.
The inverter is an electronic device that converts direct current (DC) into alternating current (AC). Renewable energy sources such as PV modules and wind turbines make DC power, and batteries will store DC power. Batteries are the least expensive and most universally applicable energy storage method available. Batteries store energy as low-voltage DC, which is acceptable, in fact preferable, for some applications. A remote sign-lighting system, or a small cabin that only needs three or four lights, will get by just fine running everything on 12-volt DC. But most of the world operates on higher voltage AC. AC transmits more efficiently than DC and so has become the world standard. No technology exists to store AC, however. It must be produced as needed. If you want to run conventional household appliances with your renewable energy system, you need a device to produce AC house current on demand. That device is an inverter.
Inverters are a relatively new technology. Until the early 1990s, the highly efficient, long-lived, relatively inexpensive inverters that we have now were still a pipe dream. The world of solid-state equipment has advanced by extraordinary leaps and bounds. More than 95% of the household power systems we put together now include an inverter.
Modern brand-name inverters are extremely reliable. The household-size models we sell have failure rates well under 1%. Efficiency averages about 85%-90% for most models, with peaks at up to 95%. In short, inverters make life simpler, do a better job of running your household, and ultimately save you money on appliances and lights.