The reason for this increasing interest on PV/T hybrid technologies is probably due to the development for the Building Integrated Photovoltaic Application getting always greater in different countries and that many projects require roof installed solar thermal collectors. From that concept the idea to develop both the technologies is straightaway. From an economic point of view there is a reduction of the expected costs and a less competition for the needed space. From an economic point of view the transition to an integrated system results more efficient than the two parted components.

Project criteria that need to be observed are:

1) Vapour and water tightness

2) Aesthetics (Colour, look, shape)

3) Insulation

4) Modularity

5) Simplicity

6) to fit to the energetic required.

The main actors playing an important role on the market should be

1) Technicians (Engineers, architects)

2) The Industry

3) Research centres

DEVELOPMENT

Though at the moment different counties are keen to develop the PV/T technology it is Israel that has reached very interesting levels of applications.

There have been some experienced since 10 years that have proved to be cheap at the climatic and marketing conditions of Israel. They own a technology that seems to match the needs of thermal and electric of a single flat. The cost is about 2000 euro per square meters ( year 2000). The thermal gain is about 1.5 kWh/m2 and the energy production is 0.4-0.8
kWh/m2/d. The pay-back period is less than 3 years. The marginal cost of PV integration is 3 $/Wp

Still exists the need for research and development on the following items:

a) Performances of the component (thermal and electrical aspects and so on)

b) Prediction of the reliability on different climatic situations and seasonal estimation

c) compatibility with existing rules and codes

d) maintenance aspects

e) life time

It is possible to foresee for the near and far future the following deadlines:

Short period: it is necessary for the market preparation

Medium period: development of competitiveness (costs, aesthetics and comfort)

Long period: completion of the integration process.