Solar paint is a liquid with photovoltaic (PV) properties that allow it to absorb sunlight and convert it into electricity. Paint a piece of glass or some other surface that has a circuit attached to it, and you’ll have your own solar cells. Its main virtue is its versatility.
How solar paint works.
The solar paint uses perovskite, a promising crystalline mineral compound that can catch light.
Inexpensive to produce and as efficient as silicon cells at capturing energy from the sun, perovskite solar cells are the cutting-edge technology to replace or compete with crystalline silicon solar cells.
Its current disadvantage is its short lifetime compared to silicon-based photovoltaics, which is currently the subject of much research.
Perovskite solar paint can be more easily integrated into building surfaces (a major source of greenhouse gas emissions), window panes (reducing the need for air conditioning), roofs, vehicles or, in fact, virtually any type of surface.
Incorporating a layer of clear coat material over the solar paint can also produce 10 times higher electrical conductivity than solar paint alone.
Other forms of solar paint include innovative technology that absorbs water vapor and splits it to generate hydrogen, which can enable buildings to produce their own fuel oil; “quantum dotswhich uses nanocrystals (essentially tiny glass beads) and quantum mechanics to improve the ability of normal solar cells to generate electrical current by up to 20%; and silicone-based paints used in concentrated solar power plants to increase solar energy absorption.
Advantages of photovoltaic paint.
One of the environmental benefits of solar paint is the speed with which it can be produced and applied.
It is already difficult for manufacturers to meet the growing demand for solar panels, and this demand is expected to increase as the price of solar energy (now the cheapest on the planet) continues to fall and governments turn to cheaper, climate-friendly sources.
The solar paint can be applied in the same way as a copier or a printing press: the ink is applied to a sheet of flexible glass which passes through a press. This production process requires fewer materials and also consumes much less energy, which means higher EROI (energy return on energy invested) and therefore lower emissions during the production of solar cells.
But solar paints don’t need to convert sunlight into electricity to reduce greenhouse gas emissions. Air conditioning accounts for 17% of electricity consumption in the United States alone and is expected to increase as global temperatures rise. Paints made with “passive radiative cooling” properties can block sunlight and reduce surface temperatures of building roofs and exterior walls. This could allow buildings to reduce their cooling costs by up to 15%, giving solar paint a significant contribution to reducing carbon emissions.
Perovskite solar paints.
Perovskite-based sun paints face their own challenges, including the fact that they use a lead-based absorber that can be hazardous if released into the environment.
Although the amount of lead used is minimal, it doubles the efficiency of perovskite solar cells, so to date the best solution is to create barriers to prevent lead leakage.
One solution, which absorbs lead when solar cells break or malfunction, is only 96% effective, yet the human body does not tolerate lead, so if perovskite sun paint becomes widespread, the threat lead will remain.
A more recent method, involving the use of phosphate salts to prevent lead from entering the environment, seems more promising. Alternatives to lead are also being explored.
Is solar paint available?
Solar paints are not yet commercially available, but their development follows the path of many advances in solar technology since the 1970s.
First, government labs and universities support basic research, then initially expensive new technologies are brought to market by start-ups, with more failures than successes.
Then a successful version of the technology (if it were to be developed) takes hold in the existing industry. The increase in efficiency drives sales and as sales and production increase prices fall, until the new technology revolutionizes the entire industry and becomes the dominant player in the market. .
The race to bring sun paints to market is backed by more than a decade of research by scientists at universities around the world.
In 2019, Google filed a patent application for a solar paint. This indicates a broader interest in the technology by major players. But most of the research and development has been done by startups looking to be first to market.
Whether solar paint follows the same path as solar PV remains to be seen. It could be that the next time you’re able to paint your house, you end up keeping the lights on with your paint of choice.