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Based on the diesel they are saving, the average output of the system they have installed is about 40kW. Depending on what assumptions you make about sunshine hours, you'll need roughly 80 x 3kW roof mounted systems to do the same job at a cost of around $2.4 million.How much would it have cost to pay 100% of the price of supplying, installing and grid connecting individual 3MW solar power panel kits for each and every building in the town. Assuming 2 pp home & approx. $40,000 per kit all up, (see ref http://72.14.235.132/search?q=cache...ome+solar+power+kits&hl=en&ct=clnk&cd=2&gl=au ) that would be a snip at a mere $2Million - a saving of $2.5 Million!!
Not only that, but such systems would feed back a significant oversupply of solar generated power (most homes would need only around 2.0-2.5 MW of power per day) into the grid to benefit whoever (as well as providing much-needed money in the pockets of the townspeople to SPEND - a laudable cause atm eh, Mr Rudd?).
HOWEVER by their very nature these systems will supply far more energy than that during the day and none at night, their operation depends on the grid and centralised generation remaining the major source of supply. So cheaper, but less energy produced on average since much of it will be wasted unless a storage system (eg batteries) is also built. And if you build that then factor in the maintenance costs it doesn't look so attractive financially.
I don't have all the technical details of the system they have installed other than the my calculations on output. But from the photos it looks like it's thermally based and presumably includes some sort of storage (?). If that's the case then it's going to work a lot more effectively, for more hours in the day, than PV panels on roofs.
As for the average output, you could get the same gross output from wind at about $25,000 - $30,000 per year which makes solar look rather expensive. That wouldn't give you 100% renewable energy though, diesel would still be around two thirds of the total, but if you add in a vanadium redox battery and a pumped storage scheme then you can have 100%. And if done on a large scale to feed a major grid that's a lot cheaper than solar.
As for my comment about it being only a part of the town's energy use... It supplies their business and household electricity. But it doesn't supply transport fuel. It doesn't contribute to the energy used to smelt the aluminium used to make the cans the local pub sells. It doesn't run the aircraft the PM and others flew in. It doesn't supply the very substantial amounts of energy used to build it in the first place. Households only use about 11% of total energy consumed so whilst it's not a bad thing to be supplying that from solar, it's by no means a solution to the overall energy / emissions situation.
So my point is just that you would be wrong to think OK, let's just scale this up, build one in every town, and the whole country will be off fossil fuels forever. No it won't - it will save a few % and no more. A nice idea and I'd be 100% for it if it can be made as productive as other renewable energy sources. But it's no magic bullet to the overall situation and neither is anything else at this stage - that's the problem.
As for the other comments about the cost of running a solar HWS, I'd simply observe that many of the commercially available systems impose some pretty nasty load profiles on the grid and this ramps up both cost and emissions from electricity generation. Those costs are, via the tariff structure, largely passed back to consumers.
I've done rather a lot of research into solar HWS and basically I'd say that it's anything but straight forward which is the best way to go and it's not a "one size fits all" situation at all. What works well in one situation will be an outright dud in another. Anyone who wants to get into the detail - perhaps we should start another thread for solar HWS?