The excellent solar energy availability in Portugal (between 1,740 kWh/(m2 year) in the South and 1,430 kWh/(m2year) in the North for solar radiation in the horizontal), gives Portugal the opportunity to decrease its traditional dependency on energy imports. The imports are coming down in the last years mainly due to wind energy contribution, but also due to a combined contribution of energy efficiency measures and other renewable energy sources, such as large hydro, biomass and also solar. Since 2010, the dependency of the country in conventional energy imports is below 80%. It reached a minimum in 2014 (70,5%) and but in 2017 it reached 77.7% (General Direction of Energy ).
The large solar resource has always been and incentive to the use of solar thermal collectors and systems, which was initiated in the 1970s. Over the years, the public policies gave mainly fiscal incentives to the installation of solar thermal systems for Domestic Hot Water preparation. Despite these incentives, the total collector area installed until 2000 was 219,500 m2 .
In the first decade of this century, public policies were implemented to profit from this resource, but imposing the “quality” paradigm in the technology and system installation services. In 2001, a programme called “Solar hot water for Portugal”  was implemented, and it introduced the following certification schemes:
for solar thermal collectors and systems, in a very similar way to Solar Keymark, which was also implemented at the same time at the European level;
for installers of solar collectors and systems.
In 2002, the Directive 2002/91/EC of the European Parliament and of the Council on the energy performance of buildings, was published and the work of transposition to the Portuguese law was initiated. Benefiting from the work performed in the frame of the programme “Solar Hot water for Portugal”, the transposition of the directive introduced the obligation of use of solar thermal collectors for hot water preparation in new buildings and large renovations. This obligation was accompanied by the following criteria: only solar thermal systems with certified collectors, installed by certified installers and having six years guarantee, could be accepted in the framework of this obligation.
These policies were important for the growth of the solar thermal market. Some fiscal incentives also supported the growth of the market. Fiscal incentives were directed to families with deduction in the individual income tax and to corporate income tax (during a few years a very beneficial condition was possible: amortization of investment in renewable energies could be done in four years).
In 2009, a strong incentive program (http://www.paineissolares.gov.pt/faq-mst2009.html) busted the growth of the market specially in the domestic sector (the price of solar thermal systems for family houses could be acquired with a reduction in price from 30% to 60% depending on the typology and size of the system). Deduction in individual income tax could also be applied. In 2010, the incentive was directed to the social-service sector, but the financial crisis stopped this incentive as well as the fiscal incentives).
Statistics on the number of collectors installed are not available since 2016. In that year, the installed collector area was around 1.2 million m2 of collectors, mainly in the domestic sector.This puts the Portuguese market on a modest place within European countries (<200,000 m2 annual), although with average installed capacity per 1,000 inhabitants of 74.7kWth when European average is of 70.7 (values for 2018 according to “Solar Thermal Markets in Europe - Trends and Market Statistics 2018, ESTIF, November 2019).
In the National Action Plan for Renewable Energies (PNAER), it was foreseen that solar thermal collector installationw would have an 11.5% annual average rate until the year 2020, to achieve a total capacity of 2.2 million m2. However, contrary to the objectives of the Plan there was an annual average decrease of 30% between 2010 and 2012 and a decrease of 37% in 2013. From 2013 to 2014 and from 2014 to 2015 the decrease was of about 9% each year. An increase of 2% in 2018 is considered in “Solar Thermal Markets in Europe - Trends and Market Statistics 2018, ESTIF, November 2019.
The national energy and climate plans (NECPs) were introduced by the Regulation on the governance of the energy union and climate action (EU)2018/1999 , agreed as part of the Clean energy for all Europeans package , which was adopted in 2019.
Portugal developed its Integrated National Plan for Energy and Climate for the period 2021-2030 and the final version was submitted to the EU in December 2019.
For solar thermal, PNEC indicates “In buildings, the solar thermal should coexist with other technologies of great potential and efficiency, such as biomass boilers and heat pumps. Still, it will maintain a significant role in the preparation of hot water, and in addition to other efficient solutions, it is one of the most efficient ways for space and water heating, contributing to the increase of comfort. In the case of industry, the capacity to satisfy low / medium temperature heat needs is expected to grow substantially.” And it predicts that solar thermal will contribute a total of 91, 89 and 86 ktep for 2020, 2025 and 2030, respectively (see Table 11 of PNEC) to the share of renewables in Heating and Cooling, which is considered to be 34%, 36% and 38% of the total energy consumption in 2020, 2025 and 2030, respectively. It also considers that solar thermal is able to contribute to energy needs in Industry in complement to biomass and higher electrification and digitalization of the sector.
Another important document of Energy policy is the “Roadmap for Carbon Neutrality 2050 (RNC 2050) - Long-Term Strategy for Carbon Neutrality of the Portuguese Economy in 2050”  where the same role is foreseen for Solar Thermal.
 Data available in http://www.dgeg.gov.pt, viewed on 26-05-2020, excel “indicadores energéticos.xlsx” with data until 2018
 ADENE/INETI (2002). “Fórum Energias Renováveis em Portugal – Uma contribuição para os objetivos de política energética e Ambiental”. Eds. Hélder Gonçalves, António Joyce, Luís Silva, ISBN-972-8646-05-4. Chapter “Solar Térmico Activo” (page. 30 to 67), Prepared by Working group coordinated and edited by M. Collares Pereira, and M.J. Carvalho
 Resolution of Ministers Council nº154/2001; Água Quente Solar para Portugal, ADEME/DGE/INETI, Novembro 2001, ISBN 972-8646-02-X
 Directive 2002/91/EC of the European Parliament and of the Council of 16 December 2002 on the energy performance of buildings, withdrawn and replaced by Directive 2010/31/EU of the European Parliament and of the Council of 19 May 2010 on the energy performance of buildings.
 Resolução do Conselho de Ministros n.º 107/2019, Diário da República, 1.ª série — N.º 123 — 1 de julho de 2019.