In my opinion, the future use  of solar power is for the generation of electricity because this type of energy source is one of the component of the so-called "renewable energy sources".  In addition, solar photovoltaic has an important role to play in building integration and many countriess from all region has been developing this new form of using solar photovoltaic.

It has been estimated, that within the EU the renewable energy sources share in electricity sector would be around 35 % in 2020,if the 20 % target for renewable energy sources is achieved. In the EU, renewables accounted for almost 70 % of additions to electric capacity in 2012, mostly from solar photovoltaic and wind power. In 2011, renewables met 20.6 % of the region’s electricity consumption and 13.4 % of gross final energy consumption. Renewables made up just over half of total net additions to electric generating capacity from all sources in 2012. By year’s end, they comprised more than 26 % of global generating capacity and supplied an estimated 21.7 % of global electricity, with 16.5 % of electricity provided by hydropower. Industrial, commercial, and residential consumers are increasingly becoming producers of renewable power in a growing number of countries.

During the five-year period 2008–2012, installed capacity of many renewable energy technologies grew very rapidly, with the fastest growth in the power sector with the purpose of reducing the use of oil and coal, and in some specific cases nuclear energy. Total capacity of solar photovoltaic grew at rates averaging 60 % annually. Concentrating solar thermal power capacity increased more than 40 % per year on average, growing from a small base, and wind power increased 25 % annually over this period. Hydropower and geothermal power are more mature technologies and their growth rates have been more modest, in the range between 3 % and 4 % per year as average. Bio-power is also mature, but with steady growth in solid and gaseous biomass capacity, increasing at an average 8 % annually (REN 21, 2013).

The participation of concentrating solar thermal power in the generation of electricity increased 18 % during the period 2007-2012.      

In terms of new power generating installations as a whole, 2011 was a record year in the EU, with 44.9 GW of new capacity connected to the grid, a 3.9 % increase compared to 2010. Wind power accounted for 21.4 % of new installations, the third biggest share after solar photovoltaic (46.7 %) and natural gas (21.6 %). More renewable generating capacity was installed in the EU than ever before representing 71.3 % of all new installations. Since 2008, renewable capacity installations have represented more than half of all new installed capacity. In total, 302.6 GW of new power capacity has been installed in the EU since 2000. Of this, 28.2 % was wind power, 47.8 % other renewables, and 90.8 % renewables and gas combined. It is important to highlight that the net growth since 2000 of gas power (116 GW), wind power (84.2 GW) and solar photovoltaic (47.4 MW) was at the expense of fuel oil (down 14.2 GW), nuclear (down 13.5 GW) and coal (down 10.3 GW)

The other renewable technologies (hydro, biomass, waste, concentrating solar thermal power, geothermal, and ocean energies) have also been increasing installed capacity over the past decade, albeit more slowly than wind and solar photovoltaic

Thank you for your very detailed answer. I agree with you about the great expansion of renewable energies. But I would discuss the issue of the integration of solar technologies (photovoltaic. solar thermal, hybrid PV/T) into the building. Do you think that the next generation of such systems is more and more integrated into the buildings ?

Yes, particularly solar photovoltaic systems

Solar thermal and hybrid just seem to have an increasingly tough time hitting their paybacks for large installations, not because either of those are deficient, but because the juggernaut of PV has rolled so strong and so hard through the building technologies sector. PV keeps making it harder for everything else to compete.

My approach on this is to assume that the human cost is innevitably the expensive one ... mistakes cost more than high technology, training is expensive, people rotate through jobs, they call in sick, they vary the way they interact with systems.

PV seems to be best positioned to minimize the human cost of power. Once installed the maintainance is minimal, there are few integration problems of weather-sealing like with hybrid systems, not having to maintain and replace things like pumps and compressors is helpful. I've seen some wonderful hybrid technologies, but they are innevitably custom made and just can't compete on power with PV which is rolled off of assembly lines like taffy. PV was just the lucky one to benefit from scale integration, partly as a byproduct of the semiconductor industry. The regulations, building codes and processes are being optimized for PV in ways that they just can't standardize for less-popular systems.

I think there is a good future for passive solar heating and energy storage, especially when combined with heat pumps, but the trick with those is to use simplicity as a design feature.

The problems you mention about integration with PV are with us for solar thermal and hybrid as well, they all need variations in code and training. But with PV, the whole inductry is working to the resolution of the integration issues.

In conclusion, I'm sure that solar thermal and hybrid systems have their place in certain applications and climates in buidling technologies, but only a fool would bet against straight-ahead PV, it's the baby gorilla of the energy industry.

Thank of lot for your very straightforward opinion. I would like to add some comments on it, and ask for your opinion

I understand that thermal part of PV/T system is the most problematic, if flat plate collectors and their application in residential buildings are focused on, integration of systems is technically more challenging than simple roof installations, but in my opinion the main barrier is the lack of knowledge among all participants in the solar systems market, just after economic issues. Especially for architects it is very difficult to use solar technologies as a part of their palette due to insufficient education. Especially for façade solutions a stronger awareness of solar technology is required for the selling process. As the matter of fact the synergy advantages offered by integrating solar thermal systems into façades as far as the use of hybrid photovoltaic/thermal systems are largely unknown by the participants of the market [1].

[1] C. Cappel, W. Streicher, F. Lichtblau, Christoph Maurer, Barriers to the market penetration of façade-integrated solar thermal systems, Energy Procedia 48 ( 2014 ) 1336 – 1344.

I think that the future of Solar Energy is electricity generation (Thermal-Steam) and the PV/T systems could have their place only in some building applications and climates

Dear Tina

Although not building integration, but village district energy system integration of solar thermal- 

Discrete cogeneration optimization with storage capacity decision support for dynamic hybrid solar combined heat and power systems in isolated rural villages

https://www.researchgate.net/publication/303256411_Discrete_cogeneration_optimization_with_storage_capacity_decision_support_for_dynamic_hybrid_solar_combined_heat_and_power_systems_in_isolated_rural_villages

Article Discrete cogeneration optimization with storage capacity dec...

My answer is YES. PV/T is the future of solar energy systems. Please, check the following book and particularly the last chapter, which discuss the future trend, prediction and expectation of PV/T technologies.

Ali H A Al-Waeli, Hussein A Kazem, Miqdam T Chaichan and K Sopian, “Photovoltaic/Thermal System: Principles, Design and Applications”, 1st Edition, Springer Nature 2020, ISBN: 978-3-030-27824-3.

Link: https://www.springer.com/gp/book/9783030278236

I completely agree with Dr. H.A.Kazem. It would be interesting to know that the integration of renewable energies in the building, was very common in traditional urban design. Although their applications may change due to technological advances regarding PVT and PV systems, the concept remains the same. The following paper investigated the applied methods of using renewable energy in Iranian traditional urban design:

Conference Paper Investigation Of Applied Methods Of Using Passive Energy In ...

Thank you for our interesting answers.

About PV/T systems,I would like to inform you that there is an IEA Task:

Task 60

PVT Systems: Application of PVT Collectors and New Solutions in HVAC Systems

web site:

http://task60.iea-shc.org/

Project (Task) Description

This Task will focus on the application of PVT collectors with the aim to assess existing solutions and to develop new system solution principles in which the PVT technology really offers advantages over the classical “side by side installations” of solar thermal collectors and PV modules. Energy  production, competitive cost, safety and reliability of systems are therefore in the scope of the Task !

Hello Mr. Marco.

Thanks for the information