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SILICON
CHIP
www.siliconchip.com.au
Publisher & Editor-in-Chief
Leo Simpson, B.Bus., FAICD
Production Manager
Greg Swain, B.Sc. (Hons.)
Technical Editor
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Jim Rowe, B.A., B.Sc
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ISSN 1030-2662
Publisher’s Letter
Hybrid solar systems can work well
This month, we have a report on a hybrid solar system
that I recently visited, just outside the NSW country
town of Yass, thanks to an invitation by the owner, Geoff
Woodman. It answers a lot of questions that readers
may have about hybrid systems, especially if they are
mulling the idea of going “off-grid”. I must admit that I
have not been enthusiastic about grid-tied solar systems
and particularly not the generous subsidies that were
originally available. While they were a boon to anyone
making an early installation, they were clearly unfair
to all other electricity consumers and taxpayers in general, the ones who had
to foot the bill for those generous subsidies.
But now solar panel installations are being made on a much more sound
economic basis. Many commercial and industrial buildings and even some
shopping centres are being fitted with quite large installations and with grid
feed-in not being part of the equation. Instead, the idea is that all the power
(OK, energy for those who are pedantic about it) being generated on the roof will
be used on the premises. A good example of this is an installation right next
door to our own premises in Brookvale, Sydney. Rated at 37kW, it will mainly
run the ovens and lighting in a crash repair business. Makes sense, doesn’t it?
Mind you, if we have a blackout in the area, that business will be blacked
out too, as this is not a hybrid installation; no batteries are involved.
The installation at Yass is a full hybrid system, with a large battery bank and
only limited grid feed-in allowed. What does get fed in gets a low feed-in tariff
of $0.06/kWh. The aim of this system is to be largely self-sufficient, with enough
solar panel and battery capacity to support the household for 24 hours or more,
with or without the electricity grid. In fact, since the main electrical load is a
reverse-cycle air-conditioner, if this was only used sparingly, the installation
could probably run indefinitely with the electricity grid being out of operation.
But the installation is tied to the grid and that means that the owner has
the assurance that he should have electricity all the time, even allowing for
occasional power outages and during days or weeks of very overcast or wet
weather. He even has the option of being able to charge the battery bank at
night, using the off-peak tariff.
Mind you, he still has to pay the daily service charge and as most people
know, these charges have increased at a far greater rate than the increase in
power tariffs. In my opinion, the energy retailers are being most unfair with
this practice. You can argue that their own cost of electricity is going up but
there is little justification for the very large increases in daily service charges
that have been made over the last five years or so. To give an example, the daily
service charge for our own premises is now $1.75. That really rankles with me.
It is those large daily service charges which are partly driving some people
to consider going “off-grid”. To me, that is still not an economic proposition,
particularly for those living in cities and towns. And you are definitely “on
your own” if your solar system develops a fault and a major component like
the inverter needs service or replacement. Inverters are the weak link in these
systems and they often fail just after the warranty runs out.
Yes, systems like Tesla’s Powerwall may change the financial equations but
we will have to wait and see. It would seem that if the electricity retailers
saw a general trend with their customers going “off-grid”, they would quickly
modify their approach with their tariffs and daily service charges, in order to
retain as many customers as possible.
Leo Simpson
Recommended and maximum price only.
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