batteries and backup systems for wind and pv solar

Off-grid electric wind systems demand a battery bank: a set of batteries wired together to store energy for non-windy days. Similarly, PV solar systems also require a battery bank, to face wide periods of meager sun resources.

Size

These battery systems are usually sized to keep home electricity running for two or three non-windy days (in the case of wind systems), or, say, a week of non-sunny days (in the case of solar PV systems). But this depends strongly on the local wind and solar trends.

Types of batteries

Battery Lead-acid batteries are the most common. The cheapest lead-acid batteries are the flooded type, though they have a disadvantage: they demand the addition of distilled water whenever there is a loss of water during their charging.

Sealed gel-cell batteries (freeze-resistant batteries) are a good choice in cold climates and in freezing spaces. Non-deep-cycle batteries aren’t suitable in wind and solar electric systems.

Battery storage lifetime

The typical lifetime of a battery storage system is around 6-10 years (depending on their type), which is much shorter than the lifetime of wind and PV solar systems.

Backup engine-generators & Off-grid wind and pv solar systems

Backup engine generator for wind and solar systems Off-grid wind and off-grid PV solar systems rarely run without an engine-generator fueled by gasoline, diesel, biodiesel or propane. This backup system is crucial for long non-windy and non-sunny periods, though they will typically run only for short periods: 100-200 hours per year, in most cases.

Sizing the battery and the backup fuel systems

Obviously, it is possible to size a solar or wind system and a battery bank to cover long adverse periods, though that doesn’t make economic sense. If you want to bet on renewable energy sources, a hybrid wind-PV solar system is a good way to avoid a too large backup fuel system.