What Are Solar Trees? How Do They Work?

A solar tree is a structure resembling a tree that generates solar energy using photovoltaic (PV) panels. It employs principles of biomimicry, using a natural system—in this case the form of a tree—to help solve a pressing global challenge: Replacing greenhouse gas-emitting energy sources like coal, oil, and gas with renewable energy.

These attention-grabbing installations generally have a sturdy metal, plastic, or stone base that extends up and out into “branches” on which solar panels are mounted. Beyond this basic structure, there is great diversity in the design of solar tree units, reflecting innovative responses to particular environments, climates, and local energy needs. 

One of the most recognizable collections of solar trees in the world is in Singapore, where in 2012 the National Parks Board unveiled Gardens by the Bay, a remarkable botanical project that included an installation of 18 artificial solar-powered Supertrees towering up to 150 feet high with canopies resembling upside-down umbrellas. These colorful steel trees not only generate solar energy, but help regulate temperature, collect rainwater, and serve as vertical gardens for flowers, ferns, and climbing vines.

How Does a Solar Tree Work?

The solar tree’s photovoltaic “leaves” absorb sunlight, converting it into electricity that is conducted down through the trunk-like central pillar of the structure to an internal battery. Many designs feature rotating panels that can move throughout the day in order to capture the greatest amount of sunlight.

While most solar trees don’t generate an amount of energy comparable to a rooftop solar system, some designs are surprisingly powerful.

Environmental Impacts

Solar trees are utilitarian stand-alone energy generating units that help power homes, businesses, and public services like lighting and electronic device charging. But the power generation potential of solar trees is relatively limited, and their primary purpose is to raise public awareness about renewable energy by getting people to notice and interact with solar in new ways. 

In comparison to other kinds of ground-mounted solar panel installations, solar trees don't require much land. They make solar energy generation possible in land-scarce areas that can’t support vast solar canopy arrays, as well as places that lack sufficient rooftop space for panels.

In addition, solar trees create shade to help counteract the urban heat island effect and provide shelter in inclement weather such as rainstorms and heatwaves, creating greater urban resilience in the face of climate change. They also enhance public spaces and amenities, providing charging stations, powering streetlights, and contributing clean electricity to homes or commercial facilities.

At present, solar trees aren't designed as large-scale solar projects, which limits their ability to contribute to the low-carbon energy transition. Still, their striking and varied designs are attention-grabbers. This makes solar trees effective at showcasing and thereby educating people about solar energy, or promoting a business or organization’s commitment to renewable energy. 

Solar Tree Companies

A number of solar companies offer commercial and residential options for installing solar trees. Here are a few top solar tree companies in the U.S. and abroad.

Spotlight Solar

This North Carolina-based company is a Certified B-Corporation that produces several solar tree designs. Their products have been erected at zoos, sports stadiums, swimming pools, schools, utility companies, and even the Kennedy Space Center, among others.

These systems provide shade and power lighting, portable electronic device charging, and even built-in television screens in come cases. While they are intended primarily for commercial and public spaces, they can also work as residential installations, although they are considerably more expensive than an average rooftop solar PV system (see below for a comparison of solar trees and solar panels). 

SmartFlower

SmartFlower, with offices in Austria and Boston, offers stand-alone solar products that mimic resemble flowers more than trees, with a sturdy central stem that opens like a circular fan into photovoltaic “petals.” From European parks to Mexican luxury resorts, this company is advancing the aesthetics of solar installations on multiple continents. At the same time, it employs an innovative approach to maximize energy production for small, stand-alone installations, mimicking a sunflower by opening and closing, and tracking the sun. 

In addition to commercial installations, SmartFlower also offers residential products, which may be of interest to those whose homes do not support rooftop solar—though the hefty price tag makes it more of a niche product than home solar for the masses.

Beam Global

Formerly known as Envision Solar, Beam Global produces both off-grid, solar-powered electric vehicle charging units and solar trees and canopies. The designs offer shade as they produce electricity, potentially offering additional greenhouse gas emissions savings as cooler cars require less air conditioning. 

Solvis

Solvis is a Croatian company that produces solar trees with graceful metal branches and leaf-shaped photovoltaic panels interspersed with LED lights, making them an attractive addition to public spaces and businesses. They can charge phones and other electronic devices, including laptops, as well as e-bikes. Circular benches that can accommodate up to 12 people surround the base of the Solvis solar tree.  

PowerTree

This India-based company produces solar units that, like SmartFlower, has PV petals, but don’t open and close. The PowerTree has an automatic tracking system that rotates panels to follow the sun, and is capable of powering LED lights, CCTV surveillance cameras, and charging phones and laptops. 

Solar Trees vs. Solar Panels

Solar panels are much cheaper than solar trees at present and have far greater energy generation capacity. In 2020, the cost of a 22-panel rooftop PV system was about $2.71 per watt, according to a report by the National Renewable Energy Laboratory. Assuming each panel is 250 watts, that's $14,905 before tax credits.

By contrast, a solar tree generally costs anywhere from $30,000 for a 1.7-kilowatt system to $100,000 for a 16.5-kilowatt system, depending on design and installation parameters—making solar trees more viable for larger businesses and public infrastructure than for many residential customers or smaller businesses.

Having said that, both PV solar panel systems and solar trees in the U.S. qualify for federal and state renewable energy tax credits and other incentives. Through the end of 2022, the federal tax credit alone can reduce the up-front cost of solar installations by more than a quarter, and by 22% through 2023.

The Future of Solar Trees

Present solar tree designs often serve as a supplemental rather than as a primary energy source—their energy generation is limited compared to other forms of solar, and they are significantly more costly per unit of energy produced. Future design innovations may bring prices down and increase energy generation so that solar tree products make up a greater share of total solar capacity and have increased value beyond green marketing or educational demonstration projects. 

Solar trees of the future have the potential to provide power in remote rural communities or other off-grid locations, powering lights, cookstoves, and some appliances in lieu of dirty energy sources like polluting gas-powered generators and charcoal-fueled fires. Likewise, some forward-looking cities are already combining solar trees with other forms of solar energy to meet their facility energy needs. In 2016, Las Vegas, Nevada became the largest city government in the United States to run entirely on renewable energy, which included solar trees installed around City Hall. 

One interesting technology that could lead to further innovation in solar trees involves the development of lightweight plastic alternatives to silicon PV panels.

These so-called organic photovoltaic technologies (organic because they contain carbon molecules) were on display at the Expo Milan in 2015, where the German firm Schmidhuber presented solar trees shaped like sprouting plants with flexible, hexagonal plastic solar panels forming “membrane”-covered shelters that also generated light. In the future, these plastic solar panels could be used in lightweight solar trees designed for places where much heavier silicon panels wouldn’t be safe or feasible.