While the PV market lurches from good to bad, like a lonely drunk, there are some issues that are a constant, and clients ask me whether PV panels should go onto the roof or into the roof. Should the PV be integrated or not?
My view is firmly not. Its a bit like asking, twenty years ago, should I build an Atari computer into my home as a Building Management System, or use a Pentium 2 to power a mainframe computer. The PV industry is maturing rapidly as a volume production industry, and already starting to exhibit the type of behaviour demonstrated by the computer industry over the last two decades, of continuous improvement in efficiency and continuous drops in cost.
The likelihood is that manufacturers will continue to innovate and improve panel performance over the next few decades to take advantage of Feed-in-Tariffs available in many countries around the world. As panel costs drop and energy prices continue to rise, it is likely that PV systems will pay for themselves in a reasonable period without subsidy within the next decade. As the panels that are already installed begin to degrade, as all current systems do over time, then a point will be reached when it is no longer cost-effective to maintain existing systems, particularly when they reach the end of a Feed-in-tariff period. At that point the panels should be replaced with a new system to get best value.
Therefore it makes no sense to me to install PV as built-in systems that cannot easily be replaced. PV tile systems will require replacement of entire sections of roofs, and there is no guarantee that those systems will be available at a point so far into the future. Other panel systems that form part of facades are even more problematic as the carrier systems that they rely on may or may not accept replacement panels. Who knows what form PV panels will take in future years. As new production systems come online, the look, thickness, size and colour of panels will change.
PV systems are in their infancy and it is best to treat them as relatively ephemeral parts of buildings, consider their integration with facades and roofs by all means, but don’t build them in, and don’t rely on them for part of the fabric performance. Make sure that they can be easily removed at any stage, and be prepared to accept that they can be replaced by a new system which may look nothing like the system that was originally designed. We cannot forsee the future of PV panel systems any more than we can forsee anything else.