Photovoltaic-thermal (PV/T) systems integrate photovoltaic and solar thermal technologies into onesingle system with dual production of electricity and heat energy. There are alternative designs to suitdifferent applications. For a given collector surface area, the overall system energy performance ishigher than the conventional "side-by-side" PV and solar thermal systems. This helps to promote PVsince the economic payback period of PV/T is much shorter. In this paper, the various water-basedPV/T systems and products are reviewed.

A method to evaluate the savings from domestic solar water heating systems

A review of the solar water heating equations in the BRE Domestic Energy Model was carried out using data from a recent monitoring project. The savings predicted by the model did not match the test data well, so improved equations were devised. Predictions from the new method were then tested against the measured savings from monitored systems and found to match the test data much better.

Solar heated water is more cost effective than retrofit insulation of facades.

A comprehensive technical and social refurbishment of a housing estate built in the seventies is carried out in the Gardsten project. Well thought out traditional measures are combined with newenergy technology which was initiated through participation in an EU project which, in turn, is based on IEA collaboration.