I have long been interested in a rigorous analysis of the actual WORTH of Solar HWS. I am an actuary who has been long retired due to ill-health. (For those who don't know, an actuary might be considered as a higher level MBA).
This is not ego driven, but advanced in the interests of a scientific (evidence based & factual) examination of the financial costs involved in the [supposed ???] energy savings associated with Solar HWS. Perhaps Lance Turner might care to moderate on this subject -possibly excluding obvious advertising spin- in the interests of gaining a DEFINITIVE[??] view on this important matter?
Solar HWS is now relatively expensive, and unlikely to significantly reduce in cost. (Unlike solar cells with thin film technological advances). A high personal cost can be defrayed by Government subsidy. BUT is this illusory? As with the insulation rebate the TOTAL costs can expand with bureacratic oversight and private sector feather-bedding.
An illuminating letter (p.16) on this in ReNew 109 detailing a two to five-fold increase (an additional 100% to 400% markup) in installation costs SHOULD have flagged a gross waste of taxpayer (OUR) moneys to the Government some six months ago.
To me it seems that the total cost to society should be considered. An alternative use of taxpayer funds might be for the Govt. put out a tender for a certain number of EXPERTLY specified products. And then to make these available in PRODUCTIVE [and societal eg disadvantaged?] situations at a subsidised cost.
Back to the practicalities. Most of Australia's population live in the major cities. Solar gain varies widely geographically. (Eg I understand that electrically boosted Solar HWS can be most effective in Alice Springs).
Average home occupancy is under 2.5 people. At present over 55% of households contain only 1 or 2 people, and this contraction in occupancy levels could continue with our aging population.
From a personal perspective. In Melbourne I have seen suggestions that the [correct] use of Solar HWS can reduce energy use by ~65%. In practice solar heating requires a tank - which involves standing heat losses. As well solar gain is seasonal - with too much at times and too little when one needs a warm shower or bath. Perhaps of most importance is that the storage tank needs to be sized to cope with (potential) household use.
I occupy a compact (European style) north facing low energy townhouse. It is two storey with one bedroom and a bathroom on each level. I live alone [part of the >55%] but an identical townhouse in the complex of a dozen units contains a nuclear family of Mum, Dad and two children in the two bedrooms. With occupancy changes on average every 7 years or less; the HWS storage tank needs to be sized for 4 people!
Were I to replace my 13 yo continuous flow gas HWS with a solar heated tank I would need to anticipate future potential demand in a 2 bedroom 2 bathroom home.
As I have long term CFS I am rapidly tiring writing this monologue. Suffice to say I believe that the high TOTAL cost over the expected operational lifespan of a FULLY sized Solar HWS GREATLY exceeds any savings to me in gas costs; even allowing for future increases in energy costs. (These increases would be based on wholesale, and NOT retail prices, and would be phased in over the longer term). For 2 people the situation would improve but is still highly unlikely to be economic.
I will give some personal usage and COST figures in a further submission.
GOH stands for Grumpy Old Hermit. I strongly agree with containing global warming; but have concerns that the money for Solar HWS may be better spent, and that the suggested energy (and greenhouse gas) savings may be largely illusory - or at the worst negative. [The position could differ, however, in a different location - eg Sydney].
