12 Solar PV Systems
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• 7–14 days for lived-in houses
• About 3 days for a recreational vehicle (RV) and for a boat with an additional
energy source, such as a wind generator
• 7–14 days for a micro-grid, or for hospitals (the value depends on the climatic
zone)
• >14 days for a telecommunication installation.
12.3.5 Balance Off Systems (BOS)—Choice
To prevent the battery from discharge and to control the off-grid system we need
further:
• A PV regulator which controls the energy flow from the PV module into the
battery. The industry offers many different PV regulators which differ with respect
to PV power, PV currents, and nominal battery voltage (typically either 12 V DC or
24 V DC ). For small PV systems there are series-/parallel-regulators and for larger
PV systems DC/DC-converters with Maximum Power Tracking (MPT).
• For larger systems one uses more and more DC/AC-converters.
• The mounting structure of the PV module is an important part of an autonomous
PV system. Especially at high latitudes in the extreme northern (or extreme southern) hemisphere, the PV panel has often a very steep inclination, as one tries to
maximize the energy yield for the “weakest” moment (Winter). Such steep inclinations can lead to high wind loads, which have to be carefully assessed. Snow
loads also have to be carefully considered.
• Finally, we need electro-technical components, such as switches, cables etc. For
DC grids special circuit breakers and fuses are needed.
12.3.6 Off-Grid Installations with Storage System
and AC-Grids
As PV panels became cheaper and cheaper, one encounters larger “off-grid installations with AC-grids”. They can power individual users, such as farm houses, alpine
huts, etc.
Furthermore, as of today, we see more and more micro-grids for communities,
airports in the desert, mines etc., which may have up to 1 MW p PV panels. These
systems replace the traditional decentralized production of electricity with diesel
generators. The diesel generator will then only be used as an auxiliary power supply.
313
• 7–14 days for lived-in houses
• About 3 days for a recreational vehicle (RV) and for a boat with an additional
energy source, such as a wind generator
• 7–14 days for a micro-grid, or for hospitals (the value depends on the climatic
zone)
• >14 days for a telecommunication installation.
12.3.5 Balance Off Systems (BOS)—Choice
To prevent the battery from discharge and to control the off-grid system we need
further:
• A PV regulator which controls the energy flow from the PV module into the
battery. The industry offers many different PV regulators which differ with respect
to PV power, PV currents, and nominal battery voltage (typically either 12 V DC or
24 V DC ). For small PV systems there are series-/parallel-regulators and for larger
PV systems DC/DC-converters with Maximum Power Tracking (MPT).
• For larger systems one uses more and more DC/AC-converters.
• The mounting structure of the PV module is an important part of an autonomous
PV system. Especially at high latitudes in the extreme northern (or extreme southern) hemisphere, the PV panel has often a very steep inclination, as one tries to
maximize the energy yield for the “weakest” moment (Winter). Such steep inclinations can lead to high wind loads, which have to be carefully assessed. Snow
loads also have to be carefully considered.
• Finally, we need electro-technical components, such as switches, cables etc. For
DC grids special circuit breakers and fuses are needed.
12.3.6 Off-Grid Installations with Storage System
and AC-Grids
As PV panels became cheaper and cheaper, one encounters larger “off-grid installations with AC-grids”. They can power individual users, such as farm houses, alpine
huts, etc.
Furthermore, as of today, we see more and more micro-grids for communities,
airports in the desert, mines etc., which may have up to 1 MW p PV panels. These
systems replace the traditional decentralized production of electricity with diesel
generators. The diesel generator will then only be used as an auxiliary power supply.