Can Solar Panels Work In Shade?

Solar panels, also known as photovoltaic (PV) panels, convert sunlight into electricity using semiconductors. When sunlight hits the panels, it excites electrons and causes them to flow, generating direct current (DC) electricity. The more direct sunlight hits the panels, the more electricity they can produce. Solar panels are designed to absorb as much sunlight as possible.

When discussing shade’s effect on solar panels, ‘shade’ refers to any obstruction that blocks direct sunlight from hitting part or all of the solar panel surface. This could be from trees, buildings, chimneys, or any other object that casts a shadow on the panels. Even small amounts of shade can have a noticeable impact on solar panel output.

How Solar Panels Work

Solar panels convert sunlight into electricity using photovoltaic (PV) cells. PV cells contain special materials called semiconductors such as silicon that naturally release electrons when exposed to light. When sunlight shines on a solar panel, the photons from the light excite electrons in the solar cells. This excitation causes the electrons to break free of their atomic bonds and flow through the material to produce electricity.

The freed electrons flow into metal conductors to form an electric circuit. The direct current (DC) electricity generated by the solar cells then travels through wires to an inverter, which converts the DC into alternating current (AC) used in homes and businesses. The inverter connects to the electricity grid or powers an off-grid electrical system.

Solar panels are made up of many individual PV cells linked together. The more light that hits the solar cells, the more electricity is produced. Solar panels work best when pointed directly at the sun without any shading. This allows the maximum amount of sunlight to strike the surface of the panels.

Why Shade Reduces Solar Panel Efficiency

Solar panels work by absorbing sunlight and converting it into electricity through the photovoltaic effect. For this process to work efficiently, the solar cells need to be exposed to direct sunlight. Shade blocks some of the direct sunlight from hitting the solar panels, reducing the amount of energy they can absorb and convert into electricity.

When shade covers a solar panel, the shaded portion can no longer generate energy. The panel operates at the level of its least efficient part. For example, if 20% of a panel is shaded, the entire panel’s output will decrease by 20%. Even a small amount of shade can have a significant impact on solar production.

According to research by EnergySage, shade covering just <10% of a panel results in a 1% drop in production. At >90% shade coverage, production drops 90%. The impact is nonlinear with partial shading leading to a disproportionate loss of power from the shaded cells. Keeping panels shade-free is key for energy efficiency.

Source: Impact of Shade on Solar Panel Efficiency | EnergySage

Dealing with Minor Shading

With proper planning and panel placement, small amounts of shade may not significantly impact solar panel efficiency. Minor shading, such as from nearby trees or chimneys, often only shades a portion of the solar array. According to Solar Reviews, partial shading of up to 15% of the array will likely only reduce energy production by 5-10% (https://www.velosolar.com/solar-panel-shading/).

To minimize the effects of minor shading, solar installers recommend optimizing the placement and orientation of panels during installation. Panels can be spaced apart to avoid shadows and oriented to maximize sun exposure throughout the day. Additionally, newer microinverter and optimizer technologies allow each panel to operate independently, further minimizing the impact of small shaded areas (https://www.igs.com/energy-resource-center/energy-101/how-do-solar-panels-work-in-shade-or-bad-weather). With careful planning, minor shading doesn’t have to be a solar dealbreaker.

Options for Heavily Shaded Areas

If large portions of your roof or property are shaded for much of the day, you have some options to still harness solar power. While full shade coverage will block solar absorption, there are creative solutions to maximize sunlight exposure.

One option is installing solar trees or retractable awnings with embedded solar panels. These structures can be positioned to avoid shade and capture more direct sunlight during peak hours. Solar trees essentially elevate the panels above shading obstacles on poles or branches. The height and angles can be adjusted to maintain optimal alignment as the sun moves across the sky.

Another solution for heavily shaded panels is installing microinverters. Microinverters are installed on each individual solar panel instead of one large inverter for the whole system. This allows panels to operate independently so shaded portions do not drag down the performance of panels still in full sun. With microinverter optimization, you can salvage a substantial solar gain even from partially shaded panels.

While heavy shade coverage makes solar systems more complex and potentially more costly, creative mounting solutions and technology like microinverters can still make solar power feasible and worthwhile.

Creative Solar Solutions

Translucent solar panels that work in low light are an innovative option for shaded areas. Companies like Onyx Solar make semi-transparent solar panels that can be installed on windows, skylights, and other translucent surfaces. These solar glass panels have photovoltaic cells embedded in the glass that capture diffuse sunlight. While not as efficient as standard solar panels, they can generate 50-150 watts per square meter in low light conditions.

Solar shingles integrated into shaded roof areas are another creative way to generate solar energy when traditional roof panels aren’t feasible. Companies like Tesla and CertainTeed offer solar shingles with integrated solar cells that look just like regular roof shingles. These can be installed on shaded northern roof faces or smaller sections interspersed between conventional shingles. While more expensive per watt than regular panels, solar shingles allow homeowners to maximize solar production on shaded roofs.

Impact of Panel Types and Technologies

The type of solar panel can impact performance in low light conditions. Traditional solar panels use silicon cells, with mono-crystalline and poly-crystalline being the most common. Monocrystalline panels tend to have higher efficiencies overall, and can produce more energy in low light compared to polycrystalline.

This is because monocrystalline silicon cells have a more uniform structure, allowing them to convert low light photons into electricity more effectively. Poly-crystalline cells have a more random structure, which can impede performance when photon energy is limited.

Emerging solar technologies using non-silicon materials like perovskites may eventually outperform silicon panels in low light. But these new types of solar cells are still in early stages of commercialization. Their stability and longevity have yet to match silicon solar panels which have proven reliability over decades of testing.

Overall, monocrystalline silicon offers the best low light performance among widely available panel options today. But ongoing advances in materials and manufacturing will open up new possibilities for solar to work effectively even in shade.

Case Studies

Real world examples demonstrate that solar can effectively operate even in shaded areas. In one installation by GreenBrilliance, solar panels were elevated above an apple orchard in Washington state (Yakima Valley) to allow for dual-use solar farming and agriculture [1]. Research showed a 30% increase in apple production compared to a control plot without solar panels. Another study by the University of Arizona found that certain crops like peppers, tomatoes, cilantro, and lettuce had equal or greater yields when grown under panels that blocked 50% of the sunlight [2].

One analysis by the National Renewable Energy Lab (NREL) found that shading could reduce the power output of fixed solar arrays by up to 50%, depending on the extent of shading. However, new single-axis tracking systems can reduce these losses to around 25% by optimizing the panel angle as the sun moves across the sky [3]. Strategically placed shade trees around the perimeter of a solar installation can also minimize interior shading. Overall, creative solar solutions exist to work around shading constraints.

Cost Considerations

When dealing with shaded areas, the costs of solar panel installation tend to be higher compared to an optimally sunny location.Specialized solar panels and inverters designed to handle shade often come at a premium. For example, microinverters can cost $200-$300 per panel, adding $1,200-$1,800 for a standard 6 kW system. Optimizers cost around $25-$35 per panel or $150-$210 extra for that system size (Source).

Likewise, high efficiency monocrystalline panels typically cost $0.50-$0.75 more per watt than standard panels. Going with premium equipment for shade tolerance could add $1,500-$2,500+ to the total installed cost. This means you’ll need to weigh the higher upfront costs against long-term energy bill savings. With optimized panels, you may still offset 60-80% of your electricity usage, versus 90-100% with full sun. While savings are reduced, you can usually still realize solid returns on investment over the system lifetime.

Every situation is different – an expert solar installer can assess the shading and provide custom cost/benefit estimates. Often, partial shading is manageable without premium equipment. But for fully maximizing savings, investing in shade-tolerant solar solutions is usually worthwhile, with sufficiently quicker payback periods despite the added expense.

Conclusion

In summary, solar panels can work in shaded areas, but their efficiency will be reduced. The amount of power loss depends on the level of shade, as even minor shading can cut energy production. However, with careful solar panel placement and advances in low-light solar technology, it is possible to successfully generate solar energy even in partially shaded locations.

While full sun is ideal, slight shade coverage does not preclude solar panel installation. Strategic solar panel placement, wiring adjustments, and improved shade tolerance through advanced solar cell technology can together maximize power generation. Though shading will reduce system efficiency and output, creative solutions can capture solar energy even in challenging shaded environments.