BY TOM SHARP – MONDAY 24TH OF JANUARY 2022
Photovoltaic solar tiles offer on-site renewable energy while preserving the aesthetics of a tiled roof. Solar tile systems are commercially available however the cost of these systems, the lower energy yield they produce and the complications of installing them have so far prevented their widespread proliferation.
Solar tiles vs. conventional solar panels
Solar tiles are significantly more expensive than conventional solar photovoltaic panels per kW of electricity produced. In the UK for example, a typical rooftop 4 kWp solar panel array would be priced at around £3,000 – £5,000, inclusive of installation. The only two companies producing commercially available solar tiles in the UK are GB Sol and Solecco Solar and these companies sell 4 kWp solar tile systems at £8,395 and £12,000 respectively, not including installation costs. The installation costs for replacing existing roof tiles will vary depending on the roof but will almost certainly add thousands more to the cost of a solar tile system.
The installation of solar tiles is typically more complicated and more costly than installing solar panels. Unfortunately, it is usually not possible to simply replace existing roof tiles with solar tiles. Instead the entire roof needs retiling with a combination of solar tiles and cheaper ‘dummy tiles’. This not only increases the installation cost but means the time to install the system balloons from 1-2 days for a conventional domestic solar PV installation, to several weeks for solar tiles.
The heavy focus on aesthetic design for some solar tiles leads them to have a lower efficiency compared to most solar panels, especially when the tiles are poorly ventilated and get too hot. Most on-roof solar photovoltaic panels currently on the market have efficiencies of around 18-22%. Some solar tiles are stylised to be similar in colour, shape and texture to traditional roof tiles and these heavily stylised designs have significantly lower efficiencies at 10-15%. Other less stylised solar tile designs can reach efficiencies more comparable to solar panels but these tiles also look a lot more like silicon solar panels which defeats the point of solar tiles for many customers.
Despite these drawbacks, solar tiles are appealing in cases where on-roof panels would not be feasible due to weight restrictions, aesthetic considerations or high wind factors. There are however other types of building integrated photovoltaics that address these issues, including in-roof solar panels. For example, the GSE in-roof mounting system from GSE Intégration allows regular solar panels to be imbedded into a roof without as much extra cost as replacing an entire roof with solar tiles and dummy tiles. When assessing whether solar tiles are the right option for a building, it is worth considering if the same needs could be met with a less expensive option such as this. In-roof solar panels are more subtle than on-roof panels and can be a more financially feasible option than solar tiled rooves in many cases.
“When assessing whether solar tiles are the right option for a building, it is worth considering if the same needs could be met with a less expensive option.”
The market today
Tesla is by far the best-known company producing solar tiles. In 2016, Tesla announced that it was developing solar tiles which would be priced similarly to the cost of traditional roof tiling plus the cost of conventional solar panels and that its ‘Solar Roof’ systems would be available in the US, Europe and elsewhere within a couple of years. Fast-forward to today and those ambitions have not been fully realised – Solar Roof is still only available in the US and like all solar tiles around the world, they come with a significant price-premium. Following price hikes in 2021, a 4 kWp Solar Roof system can be expected to cost $26,000 – $33,000 (£19,000 – £24,000) while Tesla’s 4.08 kWp solar panel arrays sell for $8,200 (£6,070) including installation. With such a large price difference, it is little wonder that the American market for solar panels is still many times larger than the market for solar tiles.
In Europe, solar tiles have been commercially available from numerous companies for a little over a decade but are not yet widely used. Most solar tiles installed to date, such as those from SunStyle or Solinso, look quite a lot like conventional solar panels just shaped like roof tiles or slate shingles. In more recent years, companies like Hanergy and PaXos have developed solar tiles which are more expensive and less efficient but are more stylised to look like traditional roof tiles. It remains to be seen whether these newer solar tiles can capture more of the rooftop PV market and compete with in-roof solar panel installations which have been far more popular.
“It remains to be seen whether newer solar tiles can capture more of the rooftop PV market and compete with more popular in-roof solar panels.”
One key difference between the European and American markets for rooftop photovoltaics comes down to the lifetime of typical roofs. The most cost-effective time to retrofit solar tiles onto an existing building is when the roof is being replaced. Standard roofs in the US are replaced every 30 years or so while roofs in Europe are generally expected to last longer and as a result relatively cost-effective opportunities to install a roof with solar tiles come around more often in the US. American companies like Tesla, CertainTeed, SunTegra and Luma Solar are leading a modest increase in uptake for solar tiles on residential buildings in the US and it will be interesting to see how the market for solar tiles develops in the coming years.
Currently solar tiles make up only a tiny fraction of the rooftop photovoltaics market and most likely will continue to inhabit only a small fraction of the market as long as solar tiles are so much more expensive to install and less efficient than solar photovoltaic panels. Rooftop solar tiles serve a niche in the market for cases in which there is a strong desire to decarbonise the energy supply of a building and a need to keep all of a roof tiled without any solar panels. While solar panels typically pay for themselves in energy cost savings in just a few years, solar tiles generally will have much longer payback periods. All of this together means that, for at least the near future, solar tiles will continue to be installed on some residential buildings but very few commercial buildings.
“Solar tiles will most likely continue to inhabit a small fraction of the market, as long as they are more expensive and less efficient than conventional panels.”
Longevity Power is a multi-disciplinary energy and sustainability consultancy which can support you in this field. We have worked with asset managers in their net-zero carbon strategies and have delivered renewable energy feasibility studies and installations across Europe. For more information on our energy practice, please contact Anthony Maguire at [email protected].