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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.) Technical Staff Ross Tester Jim Rowe, B.A., B.Sc Nicholas Vinen Photography Ross Tester Reader Services Ann Morris Advertising Enquiries Glyn Smith Phone (02) 9939 3295 Mobile 0431 792 293 glyn<at>siliconchip.com.au Regular Contributors Brendan Akhurst David Maddison B.App.Sc. (Hons 1), PhD, Grad.Dip.Entr.Innov. Kevin Poulter Dave Thompson SILICON CHIP is published 12 times a year by Silicon Chip Publications Pty Ltd. ACN 003 205 490. ABN 49 003 205 490. All material is copyright ©. No part of this publication may be reproduced without the written consent of the publisher. Printing: Hannanprint, Warwick Farm, NSW. Distribution: Network Distribution Company. Subscription rates: $105.00 per year in Australia. For overseas rates, see our website or the subscriptions page in this issue. Editorial office: Unit 1, 234 Harbord Rd, Brookvale, NSW 2100. Postal address: PO Box 139, Collaroy Beach, NSW 2097. Phone (02) 9939 3295. Fax (02) 9939 2648. E-mail: silicon<at>siliconchip.com.au ISSN 1030-2662 Recommended and maximum price only. 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