Storage Battery and Back-up Engine Generators for Off-Grid PV
Solar and Wind Systems
Off-grid PV solar and wind
systems & Storage Battery Bank
Off-grid electric wind systems demand a battery bank: a set of
batteries wired together to store energy in 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 deeply on the local wind and
solar trends.
Types of batteries
 Lead-acid batteries are the most used batteries. 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.
This implies that the
storage battery bank has to be replaced during the life of wind
and PV systems.
Backup engine-generators &
Off-grid wind and pv solar systems
 Off-grid wind and off-grid PV solar systems rarely run without
an engine-generator fueled with 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, largely dispensing
the use of the backup fuel systems, but that doesn’t make
economic sense. Eventually, if you want to privilege as much as
possible renewable energy sources, hybrid energy systems are a
good option:
wind and PV solar hybrid systems may minimize the use of the backup fuel system.
See also:
Basics on Wind electric generators
Wind Maps and data
Stand alone systems
Wind power generators technology
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Battery Storage
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