Solar Insights: Is solar hot water (and cooling) the next big thing? | RenewEconomy

Solar Insights: Is solar hot water (and cooling) the next big thing?

Remember those tubes on the roof? Solar hot water is making a comeback, along with a new brother-in-arms, solar cooling. Plus, latest data shows another strong month for PV installations in Australia, and trying to predict the world’s three biggest PV markets.


Amid the dramatic cost reductions and soaring demand for solar PV (photovoltaic) technologies in Australia and across the world, the long established idea of using the sun to heat water has taken a back seat.  In Australia, where solar hot water (SHW) once dominated the local rooftop industry, installations were outpointed by rooftop PV by a factor of 5 in the last year.

But now SHW it is tipped to make a return to centre stage, along with relatively new solar thermal technologies that use the sun to provide heating and cooling for office and building spaces, district heating and under-floor heating in cooler climates, as well as for industrial processes and in hybrid systems with solar PV (known at PV-T). At a larger scale, it could one day be used for water treatment and desalination.

According to the International Energy Agency, solar heating and cooling (SHC) could make a dramatic impact on the world’s electricity grids, providing 17 per cent of all energy required for heating in buildings, industrial processes, swimming pools, and 17 per cent of cooling needs. This amounts to 3,500GW of capacity for heating, 1,000GW of capacity for cooling, and a further 200GW of capacity for swimming pools (up from 20GW now).

The advantages are obvious. It reduces the need for new generation and cuts the burden on grids, particularly in peak demand. And it is cost effective. Solar hot water is already one quarter of the price of gas and electricity equivalents. The IEA estimates that on a global average, SHW installations cost around $US27/year over the life of the equipment, compared to around $US87 for gas-fired heaters and $US95 for electricity.

These technologies are being ramped up to district-scale installations. A recent boom in solar-challenged Denmark as brought the costs of large scale solar heating down to around $35-$40/MWh, vastly cheaper than sourcing electricity from the grid to do the job.

Solar cooling technologies are relatively new, and not widely deployed – only 711 systems were deployed in the world in 2011, according to the IEA (although Australia’s CSIRO and the Australian Solar Institute are two of many organisations leading research in the area and developing demonstration systems). The IEA suggests that solar cooling particularly useful in handling electricity peaks, because it produces at the time of  highest demand. It says the technology is already competitive in tropical regions with high electricity costs, including a 1.47MW capacity installation installed at a college in Singapore, was reportedly fully cost competitive without subsidies.

As this graph below indicates, China is by far the biggest user of solar hot water systems in the world (its line is actually cut because it doesn’t fit). It has installed SHW on more than 100 million homes, amounting to 117.6 GWth in 2010 (the equivalent of two Australian grids). It accounts for 60 per cent of the global capacity. The Chinese government’s latest five-year plan requires this number to grow to 280GWth by 2015 and to double again to 560GWth by 2020.

China is also likely the biggest market for industrial scale solar heating – because many of its industries require low heat up to around 120C – as opposed to cement, aluminium and other industries which require much more heat). The IEA estimates that China could account for one third of all solar heating production by 2050.

Another bumper solar month for Australia

The latest industry data produced by Sunwiz Consulting includes some interesting observations. First, that 115MW of PV was registered across Australia in June, virtually the same as last year. Sunwiz’ Warwick Johnston, noted that 100,000 applications were received in Queensland as the government gave notice of the winding back of its feed-in tariff, giving enough work for solar installers for another 40 weeks. Still, competition was fierce in the market, and according to Johnston, solar retailers are now absorbing some of the extra cost of large systems (above 1.5kW) caused by the winding back of the solar multiplier.

Germany and Italy finally head south

If the primary aim of the German government’s solar policy in 2012 was to reign in demand, then they have failed. But they might get it right next year. According to Deutsche Bank, German’s installation rate of solar PV in 2012 is likely to grow from the record 7GW in 2011 – with the first half running at an annualised rate of between 10GW and 12GW. But, as the proposed tariff cuts finally take effect, this run rate is expected to cause a sharp slowdown, and by next year the utility-scale sector – 1MW and above – is expected to all but disappear. Germany’s total demand is expected to be 3.5GW for 2013, although that is what was expected in 2012.

Italy appears to be having greater success in controlling its deployment of PV, deploying a subsidy cap that is likely to cause installations to fall from last year’s 9GW to 3.5GW in 2012 and 2.5GW in 2013. However, Italy, with more sun, is now offering opportunities for “grid-parity” deployment, which is expected to gather steam in areas such as Sicily. Offsetting this, are expectations that China’s market will top 7GW in 2012 and Japan’s will also grow quickly, turbo-charged by what are now the world’s most generous feed-in tariffs – designed to cut the balance of system costs by half.

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  1. Alan Pears 8 years ago

    Giles, I’m not sure I agree that solar thermal technologies will be the next big winner. We still have very little data on real field performance in mass markets of solar HW. And with issues such as no feedback to users as to whether the pump is working properly, long term maintenance, summer overheating etc I’m inclined to think that the new generation Japanese ‘Eco-Cute’ heat pump HWS units will win over solar HW. COPs of 4.5 (equivalent to about 80% solar contribution – much better than most existing heat pumps), nothing on the roof,CO2 refrigerant and potential for much lower installation costs (including retrofitting to an existing tank)and serious price reductions with economies of scale, they look interesting – especially with PV.

    Solar thermal cooling tends to be pretty complex. Combining PV with the most efficient (COP 5+) reverse cycle air conditioners offers reasonable capital cost, economies of scale, simple maintenance and a ‘beyond zero emission’ annual performance for cooling and heating (if it’s an efficient building).

    Of course, someone may deliver a market changing solar thermal solution, but it will be interesting to watch the competition.

    Alan Pears

  2. Concerned 8 years ago

    Solar Thermal Hot water.Usual installation in Australia, no moving parts.Lower cost, easy to fabricate.
    Long life, affordable, saves 20 to 30% of power cost in an average house.
    And guess what, they have solved the storage problem very cheaply.
    Heat pumps are a mechanical device which inevitably breaks, and life of unit is not satisfactory for cost.
    The life of unit is not satisfactory for cost.
    Cost of ownership?

  3. michael r james 8 years ago

    I wrote about solar (absorption) cooling several years ago in Crikey but not much news/progress? But it certainly has huge potential because it is applicable exactly where demands on the grid are growing the most (SW USA; developing Asia) and of course it perfectly matches the insolation and peak demand.
    It seems the Germans think the same because they still appear to dominate (though presumably the Chinese…). Currently restricted to large installations but that was the case for standard air-con for a long time so it is just a matter of time. I imagine Japan will pick up its interest since they use huge amounts of air-con in their humid sweltering summer and this can obviate the need for all that nuclear yet also avoid spending so much on fossil fuel imports.

    There is a 3 million wine bottle storage facility in Banyuls in the south of France that has used such a system for over 15 years now with apparently excellent reliability.

  4. Roslyn Pasfield 8 years ago

    Hi, I have some real raw data…..and anyone can ask to see it. My clients,who live in Yahl near Mount Gambier South Australia,(cool climate)an electrician by trade has kept records for 12 months on his Greenlands evacuated tube solar hot water system and has compared the results to the 12 months prior to installation and it shows over 71% REDUCTION in energy use across 12 month period.The Greenlands systems in Europe are showing lifespans of over 20 years….Any Government website shows that everyone should be dealing with their solar hot water use FIRST!!! Best investment with best returns when you use the right system.

    Did you know that you can use Solar evacuated tubes to provide heating for your entire home!!Heat is stored under home during summer in a core and released in winter.NZ and Canada have been doing it for years and the technology is now here with our first home being built in Sydney using this system.

  5. Gordon Garradd 8 years ago

    I too have some raw data- 100% reduction in heating energy use with an evacuated tube system. A 30 tube, 250litre system with backup heat when occasionally required from a 78 evacuated tube hydronics heating system, has meant zero gas or electricity use in over 2 years. No gas or electricity is connected, which makes record keeping quite simple 😉
    Yes, there has been a very occasional missed shower in that time due to the water getting down to luke warm- mainly due to using the hot water for other household purposes during extended cloudy/rainy periods, but it shows household hot water can be done purely with solar energy.
    The solar hot water system has tubes coupled to the tank, so no circulation pump is required, stainless steel tanks will last many years when filled with clean rainwater, so system maintenance is limited to hosing off dust that has occasionally blown in from western NSW/SA.

  6. Roger 8 years ago

    My data is ownership of a solar hot-water system for over 15 yrs.Just 2 months ago replaced my 2nd hot water valve flusher , that goes on all hot water systems and a odd clean. The tubes are filled with a anti- freeze / Boil liquid ( Frost area )that heats the water surrounding it and rises up to the tank above. ( 26 degree roof North facing )along with a now large Aust.Red cedar tree .Electric back up rarely used and if needed half hour before shower. My new 1.9 kw with 3 kw inverter 1st bill was a small $56.00 Credit.Power was made in mostly sunny QLD.Both of these will be smart long term items for home owners. Just do your homework and don’t use the guy who knocks on your door.

  7. Gillian 8 years ago

    Beware of averages… “The IEA estimates that on a global average, SHW installations cost around $US27/year over the life of the equipment, compared to around $US87 for gas-fired heaters and $US95 for electricity.”

    $US27 a year?

    I have a freshly minted quote for an Australian-made SHW for $5,000 installed. Over 30 years that is $150 a year.

    Given that many systems will cost well above $27 a year, I wonder where are the locations/systems where the cost is well below $27, to give the quoted average?

    • Giles Parkinson 8 years ago

      I’d imagine the 100 million installed in China would help bring down the average.

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