Is it worth waiting for residential solar roof tiles?
1. Building-Integrated solar electricity systems (BIPV) have been considered the ‘holy grail’ for some time, for good reason. When the solar electricity plant and roofing system are unitary, aesthetic issues should be minimized.
2. Cost savings would be expected both in terms of material and labor – the client is buying and installing one system that is both waterproofing and renewable energy plant.
3. Homeowners would expect fewer potential issues with leaks (and associated finger-pointing) with an integrated installation (roofing + solar).
Building-integrated Photovoltaics (BIPV) are not new – we have seen constant product change, with manufacturers releasing and terminating products (including big names such as Dow, Sanyo, and Sharp offering and then discontinuing their integrated products before exiting the solar industry completely). This disruption can leave the client with no warranty and no access to spares if ever needed in the future. Many products have had mismatched roofing system and solar electricity lifespans, e.g., 100 year roof-tile with 40-year solar cells (the roof will significantly outlive the solar plant). Aesthetic and output limitations were common (visible imperfections to the skilled eye, much less output per square foot than best-in-class solar panels). In many cases, installing the integrated systems required different skill sets (roofing and solar electricity), which aren’t typical combinations in the construction industry today.
Reasons for homeowners to incorporate solar electricity typically include saving money over time with a durable/reliable renewable energy power plant and protecting the environment. By far, the highest volume solar applications are utility-scale and commercial, both of which are cost- and space-driven, without aesthetic considerations (invisible flat roofs, open fields, parking structures). This big market brought manufacturing costs down (through standardization, competition and high volume production), while efficiency (energy per square foot), and reliability went up – these are good things that have accelerated solar adoption. So, the current expansion of solar that we see today is partially a consequence of rising energy prices / customer awareness and lower prices of solar panels in the mainstream, resulting in excellent return-on-investment for system owners.
Clearly, there are hazards with moving forward with BIPV (as opposed to solar panels), which must be weighed against the perceived aesthetic advantages as compared to proven/mature/best-in-class solar panel installations. Based on history, a homeowner purchasing BIPV could end up with an ‘orphan’ or problematic system – this should be expected when working with one-of-a-kind niche products in a small market that requires atypical installation skill sets. Yes, this could change somewhat if BIPV becomes the norm for residential systems at some point in the future. No, certain disadvantages of BIPV are intrinsic and do not apply to best-in-class solar panels – examples include much higher number of failure points (it would take a very large number of tiles to match the output of a single high-output solar panel), and considerably higher roof space requirements (to generate comparable output). Considering that a) BIPV is a technology best suited to new construction (no existing roof/new home designed to handle weight/geometry of BIPV), and b) many people building new homes want to achieve net-zero or near-zero energy (requiring maximum solar output from limited roof space), potential BIPV buyers will have to decide whether the benefits outweigh the hazards. Yes, some of the hazards of BIPV could be unacceptable to a thoughtful buyer focused on the long-term – if their BIPV system fails and can’t be repaired, or wears out prematurely, the return-on-investment, carbon reduction, and added value go away.