Monday, December 24, 2012


This is a summary of an article of mine  Why Utilities will Pay a Premium for Rooftop Solar published in REnewEconomy on 14 Dec 2012.  It was written to counter claims that people without rooftop solar (RTS) were paying more for their power so that RTS owners could be paid a 44 cent/kWh feed in tariff  much higher than the current tariff of about 23 cents/kWh .

Claims are being made that ordinary householders are subsidising rich rooftop solar owners. For example, Mark McArdle, (Queensland Minister for Energy and Water Supply) issued a media statement saying “the QCA analysis showed the solar bonus scheme currently added $26 per year to everyone’s annual electricity bill, which will increase to $90 next year if an application by Energex to the Australian Energy Regulator was successful.”

He added, “Rooftop solar costs are projected to add more than $240 per year to average electricity bills within five years.” (These claims were based on the previous government’s feed in tariff of 44¢/kWh)
So what is rooftop solar actually doing to household power bills in Queensland? And how high could the feed-in tariff go before it really would be increasing household power bills?
In the detailed section below, a comparison of demand and revenue vs time of day for 2008 and 2012 is used to answer the above questions. The quick answers are:
1. Rooftop solar is actually saving the “typical Queensland household” (without PV) $65/yr.
2. The feed-in tariff would have to rise above 96¢/kWh before rooftop solar actually stopped saving households (and power companies) money. Power companies can actually become more competitive by locking in extra contracts for the supply of rooftop solar, even if it means paying the small premium that was offered to me.
3. It is difficult to say what effect rooftop solar would have on household bills in five years’ time. My guess is that investment in rooftop solar will be justified at feed-in tariffs below what householders will be paying for power and that it will still be saving households money.

Saturday, October 27, 2012


Revised: 21 March 2013

In the 2010 Australian federal election* there was no clear result at the end of vote counting despite the ALP winning the two party preferred (2PP) vote.  In the end, an ALP minority government was formed after post election negotiations with the Greens and independents.  The LNP could have quite easily ended up as the government despite losing the 2PP vote.
By contrast, in the 2012 Queensland state election, the LNP gained a very clear majority of seats after clearly winning the 2PP vote.  The problem here was that the ALP won only 8 % of the seats (7 members) despite having 27% of the primary vote.  As a result, the ALP is struggling to hold the government to account let alone provide a credible alternative at the next election. Not a good outcome for the state.  (The LNP won 88% of the parliamentary seats despite winning less than 50% of the primary vote.)

The common link between both these problems is that single member electorates were used to decide who will become members of parliament.  The above are not the only problems associated with single member electorates.

In this article it is argued that a specific system based on two member electorates would overcome the problems that are a feature of systems based on single member electorates.

(*Definitions of the terms used here are included at the end of the article.)

Wednesday, August 8, 2012


This post was initially written to provide background information for this article on the potential benefits of moving air conditioners to off peak power. (published by RenewEconomy on 21 Sept 2012) The article argues that that gradually moving air conditioners to off peak would allow most of the proposed power system upgrades to be deferred for a long time.  The use of phase change materials (PCMs) to store cold or heat would allow this conversion to be done without reducing people's comfort levels.

PCMs are finding a markets as a compact way of storing heat or cold.  This post provides background information on the characteristics and uses of PCMs.  

Phase:  Many materials can exist in more than one phase.  For example, water can exist in the solid, liquid or gas phase.  Some materials can also exist as different crystal phases.
Phase change: The change from one phase to another.  For example, the melting of ice to liquid water.  Phase changes can be driven by changes in temperature and/or pressure.
Phase change material (PCM): A mixture or pure substance that can change phase.  The term is often restricted to materials that change phase over a narrow temperature range.