Generation Switch
Introduction
Many
people who have solar panels fitted to their houses wish to make the best use
of all the energy generated. This is
especially so if there is no export meter and the exported energy is deemed to
be 50% of the generated energy.
Designs and Projects
Most
generation meters have a flashing LED which flashes 1000 times for each kWh
generated. By sensing the flashes and
checking the flash rate it is possible to use this information to switch on electrical
loads to use up any excess power.
The
first circuit is a simple circuit in which a control can be preset to any
desired generation rate and a switch is turned on whenever the preset rate is
exceeded.
The second circuit follows on from the first. Whilst a reasonable guess can be made at a
normal base-load for the house (say 500W) and the simple circuit can be used to
switch on a 3kW immersion heater whenever the generation exceeds 3.5kW, the
circuit has no knowledge of temporary loads such as a kettle which would
cause some generated energy to be diverted to the temporary load and the
immersion would be running on imported power.
This second circuit incorporates a reset input which turns off the
switch whenever imported power is detected.
I hope to be experimenting with a remote control switch system which
can turn on the load at a point remote from the Generation Switch circuit. This would allow the Generation Switch
circuit to be shut away perhaps next to the import and export meters and
the load, such as an immersion, remotely controlled by an RF link. I have looked at developing this system but
in the limited time available so far have not found a suitable remote
controlled power switch one in which the remote control is operated by a
simple single contact switch.
The next stage of the design takes a step back and looks at producing a
generation switch from an entirely different angle. Why are we checking how much is being
generated by the panels, when really we need to look at how much spare power is
being exported? We should be able to
measure the exported power and turn on loads to reduce this to a minimum. This is a longer term project with some
results during August 2012.
