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Solar District Heating (SDH)
“More and more countries recognise that solar thermal district heating is the most cost-effective way to decarbonise the heating sector”, explains Guthrie. The first SDH installations above >500 m² (350 kWth) came online in France, Serbia, Australia and Kyrgyzstan. In total 15 large-scale solar thermal systems were added in 2017 mostly in the established markets as Austria, China, Denmark, Germany and Sweden. For the first time parabolic trough collector technologies were used for feeding energy into district heating networks. The largest installation started operation in Inner Mongolia in October 2016 (75,000 m2) followed by a Danish installation with 26,929 m2 in the municipality of Brønderslev (see photo).
Residential markets under pressure
Due to increasing competition with other renewable technologies in the residential sector and the continuously low fossil fuel prices throughout 2017, new installations in China and Europe declined. The added global solar thermal capacity of around 35 GWth was down by 4.2 % in 2017.
This downward trend of the previous year flattened out somewhat in China last year due to the rising demand for solar space heating and solar water heaters for large real estate projects. New installations in China declined by only 6% relative to 2016, which saw a 9% one-year market decline, following an even larger year-to-year contraction (-17%) in 2015.
Market growth was recorded in India (26%), Mexico (7%) and Turkey (4%). All three markets have cost competitive residential solutions and no direct subsidy schemes in place. Therefore it is no surprise that India and Turkey have the lowest solar hot water prices with 2 to 3 €-ct/kWh according to the Levelised Cost of Heat calculations in chapter 5. On the high end of solar heat costs are France with 19 €-ct/kWh for small systems and 14 €-ct/kWh for multi-family houses, and in Denmark with 16 and 12 €-ct/kWh respectively.
Other key market trends
Collector technology depends on the region: Vacuum tube collectors dominated the global solar thermal capacity in operation (72%), whereas flat plate collectors are most common in Europe (83%).
In 2016, solar thermal systems in multi-family houses, hotels and schools contributed 27% to globally produced solar heat. Solar water heaters for single family houses reduced their market share slightly. Swimming pool heating (4%) and solar combi systems (2%) were niche markets.
The leading countries for air collector installations were Australia, Canada, Japan and the United States. Solar air heating provides typically 20 to 30% of the annual space heating demand of buildings and dries agricultural products.