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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
John Clarke, B.E.(Elec.)
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Jim Rowe, B.A., B.Sc
Nicholas Vinen
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Dave Thompson
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4 Silicon Chip
Publisher’s Letter
Going off-grid: is it worthwhile?
One of the letters in the Mailbag pages in this month’s
issue is on the question of “going off-grid”. This is an option
being looked at longingly by many electricity consumers
as they are confronted by ever-higher quarterly bills and
if they have solar panels on their roof, the prospect of
diminishing solar feed-in tariffs as time goes on.
What might have looked like a sure-fire investment
just a few years ago, now looks somewhat diminished as
various state governments have realised the threat to their
budgets if they continued paying the originally generous
solar feed-in tariffs to those in the vanguard of solar roof-top installations.
Furthermore, as more and more solar panels have been installed, it has become
common in some areas for the mains voltage on hot sunny days to run up against
the 250VAC (or thereabouts) threshold voltage of most grid-tied inverters and
so they are throttled back to the point where they may generate very little or no
power. The customer gets zero feed-in tariff when that occurs and to add insult
to injury, depending on how their “smart” meter is arranged, they may also be
paying peak tariff.
Finally, how many people with solar panels on their roof are severely frustrated
when a blackout occurs? There are those wonderful panels on the roof, potentially
able to generate all the power they need and then some, but because of the “antiislanding” feature of grid-tied inverters, no power can be generated. To me, that
must seem like a serious injustice. Wouldn’t it be better if there was a facility for
the “anti-islanding” feature to be turned off when blackouts occur and for the
household to be temporarily disconnected from the grid so they could enjoy their
own solar electricity? Alas, that is not so.
So can you blame such people for considering the options to go off the grid and
be finally freed of those “mercenary” power companies? Trouble is, there are no
easy options. For a start, you need a new inverter without the anti-islanding feature.
Second, you probably need a lot more panels because most roof installations only
have a capacity of a few kilowatts. You need a lot more than that to cater for the
peak demand in a typical household, particularly if you want to run electric heating
and/or air-conditioning.
And then there is the most expensive component of any off-grid electric
installation – a big fat battery bank, because once you go “off-grid”, you are literally
on your own and you need to provide all of the electric energy needs all day, every
day, at night time and whether the Sun is shining or not.
Of course, if something in your off-grid power system fails, you cannot simply
phone your friendly (not so mercenary, perhaps?) power company and ask them
to fix it. Nor, if you get sick of being on your own, will it necessarily be possible to
be like the electric prodigal son to “repent and come back to the fold”.
From time to time there are articles in the press about how much of our power
generation will be “distributed” (meaning solar panels) rather than “concentrated”
(in large remote power stations) in the future. And since so much of the power
will be based on solar panels, storage in the form of batteries will be part of the
deal. All of this is predicted to become viable quite soon because of the steadily
reducing cost of lithium-based batteries. Of course, further into the future, there
will be fantastic breakthroughs in battery technology such as the “double carbon”
battery and we will all be in an electric Elysium without a care in the world.
Well, don’t hold your breath. Developments in battery technology are following
a similar path to the development of flat-screen TV sets. That went on for many
decades and finally, yes, flat screens did come into production and of course today
we have video nirvana, don’t we?
Except that in the case of batteries, progress has been arguably slower. In fact, a
century from now people might look back and wonder about all the effort to research
batteries which ultimately was futile and unnecessary because of the historic breakthrough in fusion power generation? I am betting that such a breakthrough will
occur, even though I probably won’t be around to see it.
Leo Simpson
siliconchip.com.au
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