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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. E-mail: silicon<at>siliconchip.com.au 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. 2  Silicon Chip siliconchip.com.au