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Title:
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The DC low-voltage house
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Author(s):
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Published by:
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Publication date:
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ECN
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1-9-1997
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ECN report number:
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Document type:
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ECN-C--97-058
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ECN publication
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Number of pages:
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Full text:
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80
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Download PDF
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Abstract:
The use of photovoltaic (PV) energy in buildings is usually associatedwith a connection to the public electricity grid. The grid connection
requires a conversion from direct current (DC) to alternating current (AC).
This conversion enables both the use of standard AC household equipment and a
connection to the public electricity grid. Many household appliances,
however, function internally on DC. Within the AC equipment an alternating
voltage of about 230V is transformed to a (low) DC voltage, for example 12 V.
Utilising PV energy in this way involves two energy conversions with inherent
energy losses. It is reasonable therefore to assume that these losses could
be avoided by introducing a DC (low-voltage) grid. The feasibility of 'The DC
low-voltage house' set within predefined boundary conditions is the subject
of this report. The first part of the research is focused on household energy
consumption. It became apparent that DC supply of household appliances is
possible, but does not automatically reduce energy losses. The second part of
the research concentrates on the DC low-voltage distribution system. It
became clear that due to voltage and power losses, it will not be possible to
satisfy the present power demand in households with a very low voltage
distribution system. The main problems to solve in the design of the DC
low-voltage distribution system are switching of DC currents and limitation
of short circuit currents. The results of the first two parts of the research
lead to conclusions on the feasibility of the DC low-voltage house. Observing
the boundary conditions of the project, a change from AC to DC low-voltage in
houses is not very promising. A large reduction of energy losses is not
expected. Taking other conditions and circumstances into consideration (e.g.
a very small power demand, the presence of a public DC electricity grid and
the supply of certain types of appliances), may lead to a more positive
assessment of the DC low-voltage house. 35 refs.
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