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Designing for Low Electrical
Energy Use
In no specific order:
- Select only select low
energy lights and appliances
- Use propane, wood, oil
or other fuels, not electricity for major heating appliances
- Install lots of extra
switches so that you can control phantom loads
without having to unplug appliances, also put less lights on each switch. Use
directed lighting where possible.
- use motion sensors and timer
switches, especially for outdoor lighting and areas where it is easy to leave
an electrical load on
- use heating systems that use
convection and don't require pumps and fans to circulate or move heat, when
they do, investigate whether there are DC powered alternatives.
- when possible use low
voltage DC power for things such as outdoor lights, door bells and Ni Cad
chargers and motion sensors that normally create phantom loads because they
run continually from small transformers. You already have equipment that
works well well with DC power. Examples of these are Camera and Cellular
phone chargers which are designed to operate from your car.
240
Volt Loads
Two inverters, a 240V inverter or a step-up autotransformer are required to
produce 240V power. Because 240V power increases system complexity and cost it
should be avoided if possible. Deep well submersible pumps are an exception. Due
to distance and or depth of well a 120V pump may not be practical. An
autotransformer wired in a step-up
configuration can manage water pumps to one horsepower. To keep the
transformer off-line until required wire the well pump switch to the primary
side of the transformer.
Transformers
Other than the autotransformer mentioned above eliminate transformers within
your system. Transformers are often found within equipment such as heating
systems, low voltage lighting, water softeners, etc. There are considerable conversion losses as
DC low voltage power is converted to 120 AC then down to 12V. Transformer
conversion power loss of up to 30% is exacerbated due to the
transformer's continual power loss (phantom load) even when not active. Check with your
equipment suppliers and manufacturer to see if DC power may be used directly. It
is sometimes possible as in the example of the autotransformer above, to switch
the power supply to the transformer rather than to switch the low voltage
load (e.g. doorbell).
Grounding and Bonding
Off-grid systems have multiple ground sources which should be bonded:
- PV Panels
- Inverters
- Generator
- AC Panel
- Wind Turbine
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