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What can I choose in the calculator?

The calculator lets you choose the share of total decentralised heat demand covered by Decentralised Solar Thermal energy in Switzerland in the selected year (2035 or 2050).

Decentralised Solar Thermal

image Norbert Nagel, via Wikimedia Commons


  • Impact
  • Global markets
  • Definition
  • Constraints
  • Assumptions
  • References

IMPACT – What are the impacts of Decentralised Solar Thermal energy?

In Switzerland, increasing the share of Solar thermal energy will have the following impacts:

Energy system

image Reduction of final electricity and/or fossil energy consumption.

image Increases the share of renewable energy sources in the energy mix.

image Likely to increase energy independence and energy security.

image If electric heat is used as a back-up for low solar periods (winter), then it can increase, the seasonal supply-demand gap (excess generation in summer and generation shortage in winter).

Environment & Climate

image Very likely to reduce global CO2 emissions.

image Likely to avoid emissions of harmful pollutants, especially in urban areas (heating oil-boilers can remain off in summer).

image Minimal environmental impacts due to waste (non-toxic, largely recyclable materials).

Society & Economy

image Likely to have limited impact on the cost of the energy transition, unless prices of the fuels replaced by solar thermal rise sharply.

image May improve balance of payments by substituting oil and/or electricity imports.

image Reduce Confederation income from the tax on mineral oil and electricity under the current taxation system.

GLOBAL MARKET – What is the global market for Decentralised Solar Thermal energy?

The globally installed solar thermal capacity, including district heating and industry was estimated at 268 GW (thermal) in 2012. About 200 TWh of solar thermal heat has been used for heat in the buildings sector in 2011. Of this figure about 130 TWh (thermal) have been consumed in China alone, which has been the major growth market over the past 10 years. India could be the next fast growing market as it has set the goal to install 20 million m² of solar thermal collectors (14 GW thermal) by 2022.[1]


DEFINITION - What is Decentralised Solar Thermal energy?

Decentralised solar thermal systems use solar collectors to harvest solar energy for use in the form of heat. They employ typically roof-mounted rectangular collectors made up of flat plates or evacuated tubes which capture solar radiation and thus generate heat.

The produced heat is then transferred to a water-filled thermal store and used to supply hot water and space heating energy. The thermal store can release heat for a period of hours up to several weeks, depending on the size of the tank, insulation and usage patterns.

CONSTRAINTS - What are the key barriers facing Decentralised Solar Thermal energy deployment?

• Decentralised Solar Thermal competes for roof-top area with Photovoltaics (PV). PV is often a more attractive investment due to guaranteed feed-in tariffs, whereas profitability of solar thermal hinges on prices of the conventional energy source that is being displaced.

• Unlikely to completely replace the need for a conventional water heater, so can be perceived as an additional capital cost and source of complexity, rather than as a means to save money.

• The produced heat cannot be stored for long or transported to another location, therefore much of the summer generation is wasted.

ASSUMPTIONS – What are the assumptions considered in the calculator?

Next tables contain the assumptions that have been introduced in the Photovoltaic energy model of the calculator.

Capacity factor
Monthly distribution*
0.048 0.062 0.090 0.089 0.106 0.110 0.121 0.112 0.098 0.076 0.049 0.041

*Based radiation data for the village of Verbier.

CO2-eq. emissions [kgCO2-eq./GWhth] 10'973
Deposited waste [UBP/GWhth] 1'718'064
Specific investment [CHF/kWth] 2'090


[1] Heating without global warming, Market Developments and Policy Considerations for Renewable Heat. Report by the IEA.

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d_solar_more.txt · Last modified: 2019/10/22 09:17 (external edit)