The Potential of Solar Paint: Everything You Need to Know

Solar paint is a liquid with photovoltaic (PV) properties that allows it to absorb sunlight and convert it into electricity. Paint it on a piece of glass or other surface that has circuitry attached, and you have your own solar cells. Its main virtue is its versatility.

How Solar Paint Works

Solar paint uses perovskite, a promising crystalline mineral compound that can harvest light. Cheap to produce and as efficient as silicon cells in capturing the sun's energy, perovskite solar cells are the leading technology to replace or compete against crystalline silicon solar cells. One current drawback is their lack of longevity compared to silicon-based PV—the subject of much active research.

Perovskite solar paint can be more easily integrated into building surfaces (one of the leading sources of greenhouse gas emissions), window glass (reducing the need for air conditioning), rooftops, vehicles, or indeed practically any type of surface. Incorporating a layer of transparent coating material on top of the solar paint can also produce electrical conductivity 10 times greater than solar paint alone.

Other forms of solar paint include an innovative technology that absorbs water vapor and splits it to generate hydrogen, which can allow buildings to produce their own heating fuel; “quantum dots,” which use nanocrystals (essentially tiny glass beads) and quantum mechanics to enhance regular solar cells' ability to produce an electric current by up to 20%; and silicone-based paints used in concentrated solar power plants to increase the absorption of solar energy.

Environmental Benefits

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 keep up with the increasing demand for solar panels, and that demand is expected to soar as the price of solar energy (now the cheapest on the planet) continues to drop and governments shift to more climate-friendly sources of energy.

Solar paint can be applied in the same way a copy machine or printing press works: Ink is applied to a flexible sheet of glass running through a press. This production process requires fewer materials and is also much less energy-intensive, meaning a higher EROI (energy return on energy invested) and thus lower emissions in the production of solar cells.

But solar paints need not convert sunlight into electricity in order to reduce greenhouse gas emissions. Air conditioning represents 17% of electricity use in the United States and is likely to increase as global temperatures increase. Paints made with “passive radiative cooling” properties can shed sunlight and reduce surface temperatures of roofs and exterior walls of buildings by 10.8 degrees F. This could allow buildings to reduce their cooling costs by up to 15%—giving the paint an important contribution to lowering carbon emissions.

Perovskite-based solar paints do face their challenges, including the fact that they use a lead-based absorber which can be dangerous if released into the environment. While the amount of lead used is minute, it doubles the efficiency of perovskite solar cells, so to date, the best solution is to create barriers to prevent leakage of lead. One solution, which absorbs the lead if solar cells break or malfunction, is only 96% effective, while the human organism has zero-tolerance of lead, so if perovskite solar paint reaches widespread use, the threat of lead will remain.

A newer method, which involves using phosphate salts to preclude lead from entering the environment, seems more promising. Alternatives to lead are also being explored.

Will Solar Paint Be Widely Available?

Solar paints are still not available commercially, but their development follows the trajectory of many advances in solar technology since the 1970s.

First, government laboratories and universities support basic research, then initially expensive new technologies are brought to market by startups, with more misses than hits. Next, a successful version of the technology (should one develop) gains a foothold in the existing industry. Increased efficiencies drive sales, and as sales and production increase, prices drop, until the new technology disrupts the entire industry and becomes the dominant market player.

The race to bring solar paints to market is supported by over a decade of research by scientists at universities around the world and, most importantly, at the U.S. Department of Energy's National Renewable Energy Laboratory (NREL). In 2019, Google filed a patent application for a solar paint, signaling broader interest in the technology by major players, but most of the research and development has been done by startups seeking to be first to market.

Whether solar paint follows the same path as solar photovoltaics themselves remains to be seen, but it could be that the next time you're in a position to paint your house, you may end up keeping your lights on with the paint you choose.