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SILICON SILIC CHIP www.siliconchip.com.au Publisher & Editor-in-Chief Leo Simpson, B.Bus., FAICD Editor Nicholas Vinen Technical Editor John Clarke, B.E.(Elec.) Technical Staff Ross Tester Jim Rowe, B.A., B.Sc Bao Smith, B.Sc 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 and Distribution: Derby Street, Silverwater, NSW 2148. 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 (up ramp), 234 Harbord Rd, Brookvale, NSW 2100. Postal address: PO Box 139, Collaroy Beach, NSW 2097. Phone (02) 9939 3295. E-mail: silicon<at>siliconchip.com.au ISSN 1030-2662 Recommended & maximum price only. 2  Silicon Chip Publisher’s Letter Going off-grid could be a bad idea Back in June 2015, I wrote about the “anti-islanding” feature of grid-tied solar inverters and how it meant that during blackouts, particularly in the aftermath of major storms and floods, those home-owners with roofmounted solar panels still had no power even though the Sun could be seen shining brightly. How frustrating! Two years later, the east coast of Australia has experienced a very severe cyclone which has meant that tens of thousands of people have again been without electricity for long periods while power was being restored. No-one is to blame for this; it’s just the consequence of very bad weather. Of course, now that battery-backed solar installations are being promoted, it is possible to have continuous power while thousands of homes around you are without. But that is a very expensive investment. Nevertheless, we often receive emails from people who are contemplating going “off-grid” so that they don’t have to contend with blackouts, rising electricity tariffs and daily service charges. Now while the above three aspects are certainly food for thought, I would be very cautious about going entirely off-grid. For a start, if your system breaks down, you won’t be able to have the power restored quickly and cheaply by your electricity retailer. The further you are from major population centres, the more isolated you would be. Secondly, while those daily service charges have increased far too much, the typical customer’s daily charge of about $1 (or $365 per annum) is small bikkies compared to the investment you will need to go off-grid. Thirdly, if you already have a grid-tied solar installation, you can be a lot smarter about the way it is employed. You already have a “smart meter” but you must become a “smart user”, particularly now that most states have drastically reduced those generous feed-in tariffs to a measly 6¢/kWh or thereabouts. That means you must use as much of the power generated by your solar panels as you can. (By the way, you must also ensure that your smart meter has been reprogrammed for “net” metering). If you have a pool pump and salt-water chlorinator, using power generated on-site is a no-brainer: simply run the pump during the day when solar power is available. Or operate appliances such as washing machines and dishwashers at the same time, if at all possible. To some extent, you should also run your aircon in the hot summer afternoons (before solar generation cuts out). Now while these strategies are quite easy if you always have someone at home to make decisions about running pumps and appliances while solar power is available, it is not easy if no-one is at home during the day or you go on holidays. Of course, you can set the timer to run your pool pump and chlorinator during the peak solar generation times but that can go badly amiss when the weather is bad or a blackout subsequently causes the timer to turn on the pump during peak tariff times – that gets really expensive. You always need to be vigilant about checking that the timer is correctly set. This is such a tricky issue that we are considering the design of a project which would operate a pool pump and solar chlorinator only while adequate solar generation was available. The system will also need to run the pump at off-peak times after a day or so, when bad weather has reduced the available solar power. That means it would also need GPS and to keep track of daylight saving so that it was never likely to run the pump in peak tariff times. There are other wrinkles to consider in this concept but I think it is an easier approach, if you do have solar panels and a pool, than the far more expensive alternative of going off-grid. What do you think? Leo Simpson siliconchip.com.au