Thursday14 November 2024
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Efficiency drops by 50% and albedo effect: how solar panels perform in winter and what factors to consider.

In cold weather, solar panels actually operate more efficiently than they do in the summer. Focus will explain how to maintain the efficiency of your home power station.
Потеря КПД до 50% и альбедо: как функционируют солнечные панели зимой и что важно учитывать.

How Solar Panels Work in Cold Weather

Panels function by converting sunlight into electricity using photovoltaic cells. When photons from sunlight hit these cells, they knock electrons loose from atoms, creating a flow of electricity.

It’s important to remember that photovoltaic panels convert solar energy into electricity, while solar (thermal) panels convert solar energy into heat. Most people use photovoltaic (PV) panels. However, it’s beneficial to understand how different types of solar energy collection devices operate.

The Principle of Photovoltaic Cells

Photovoltaic panels work by converting solar energy into electricity, writes snugg.com. The electricity is then connected to the home's electrical circuit for use as needed. A battery can also be installed to store the energy generated by the solar panels for later use. Photovoltaic panels perform well during the day, even when it’s cloudy. Their operational algorithm is as follows:

  • Sunlight hits the surface of the cell.
  • Solar radiation is absorbed by a layer of silicon.
  • Electrons in the silicon move, generating a direct current (DC).
  • The direct current is sent to a solar inverter, which converts it into alternating current (AC).
  • The alternating current can either be sent to your home’s switch for immediate use or to a battery for future use.
солнечные панели

How Solar Thermal Panels Work

Solar thermal panels operate by converting solar energy into heat. Condensate, i.e., hot water, collects and is then transferred to the home’s hot water supply system for heating purposes before being redirected back to the solar panel. Solar thermal panels work effectively only when the sun shines brightly enough to heat the water. The process is as follows:

  • Sunlight hits the surface of the solar panel.
  • Heat from the sun is absorbed by a special fluid, usually a mixture of water and antifreeze.
  • Heated water is pumped to a heat exchanger located inside the home’s water tank.
  • The heat exchanger warms the water in the tank without the two fluids coming into contact.
  • The used solar fluid is pumped back to the solar panel for reheating.

Solar panels utilize light, not heat, to generate energy. Therefore, even on cold winter days, the panels will continue to produce electricity as long as there is daylight.

Disadvantages of Solar Panel Operation in Winter

Several factors can affect the efficiency of solar panels in winter, reports eonenergy.com:

Shorter daylight hours. Since the sun rises later and sets earlier, there are fewer hours during the day when sunlight can reach the panels. This reduces overall clean energy production.

Lower sun angle. During the winter months, the sun does not rise as high, meaning its light must pass through more of the atmosphere before reaching the photovoltaic cells. This decreases the amount of "green" energy that can be produced.

Cloud cover. Cloudy skies are common in winter. A thick cloud cover can block much of the already weak winter sunlight. However, even on the cloudiest days, solar panels can still generate some energy. ‍

Snow. A thick layer of snow can obstruct sunlight from reaching the solar cells until it melts away. However, light snow usually melts quickly or slides off the panels.

Advantages of Winter Weather for Solar Panels

There is a positive side to how winter affects solar panels, as noted by interestingengineering.com, citing Levelling Kincha, CEO of MakeMyHouseGreen.

Low temperatures. Photovoltaic cells actually operate more efficiently in colder conditions. The reason is that low temperatures allow the electrons in the panel to move more freely, thereby increasing electricity generation power. Thus, the efficiency of the device increases by 0.5% for each degree below 25 degrees Celsius.

Albedo effect. On cold, clear days, snow on the ground can act like a mirror, reflecting additional sunlight onto solar panels. This phenomenon, known as the "albedo effect," can enable them to generate even more "green" energy in the cold.

For reference: albedo is the reflectivity of a surface, the ratio of the amount of radiation reflected by that surface to the amount of incoming radiation, expressed as a percentage — red.

Angle of inclination. Kincha noted that the dark glass coating of the panels helps snow melt faster. Additionally, the angle of inclination causes melted snow to slide off, exposing the device's surface to the sun. Only heavy snowfall can impact efficiency. However, a special striped coating has already been developed and applied that allows accumulated snow to slide off quickly, increasing the efficiency of solar power stations on rooftops.

How Much Energy Do Solar Panels Produce in Winter

In winter, the amount of energy produced by a solar panel can decrease by 50-70%, up to a maximum of 80%, according to data from snugg.com.

While a 400-watt solar panel can generate about 2.4 kWh of energy on the sunniest summer day, it may produce only 0.4 kWh on the cloudiest winter day. This is because there are fewer peak sunlight hours in winter compared to summer. A peak sunlight hour is a measurement of solar energy, but it is not the same as an hour of sunlight. It refers to an hour with an intensity of solar radiation of 1000 watts per square meter.

You can estimate the daily energy output of a solar power station using the formula:

  • Daily output (watt-hours) = Panel power (watts) × Peak sunlight hours (hours)

For example, during winter, a 400-watt panel would yield approximately:

  • 400 W × 1 hour = 400 watt-hours (0.4 kWh)

These are fairly rough estimates that do not take into account specific weather conditions, the angle of the panels, their orientation, etc. However, this formula can help provide a general idea of electricity generation in winter.

The good news is that even on the shortest and cloudiest days, photovoltaic cells still produce energy. And while one device may generate only 400 W in a day, a home with 12 panels would generate around 4.8 kWh per day — roughly half the daily energy consumption of an average home in winter.

мастер чинит солнечную панель

Maximizing Solar Panel Efficiency in Winter

Winter is the most costly time of year for heating since even the most well-designed home gradually loses heat. Therefore, it’s essential to utilize solar power stations as efficiently as possible to reduce electricity costs.

Here are some tips for maximizing solar panel efficiency in winter from KiowaCountyPress:

Keep them clean. Snow and debris can block sunlight, so it’s crucial to keep the panels clean for optimal performance. This can be done by simply directing a garden hose onto the roof or hiring a professional for a more thorough cleaning.

Adjust the angle of inclination. In winter, the sun is lower in the sky, so adjusting the angle of the panels can help capture more light. It’s advisable to hire a professional to do this safely.

Monitoring and maintenance. Regular checks can help identify any issues early, and some systems allow you to monitor the performance of the photovoltaic cells from your phone.

Remove obstacles. Large trees can block sunlight. If there’s a tree near the house that shades the solar panels, it’s worth trimming it to maximize the amount of light reaching the devices.

Install a battery. You can store excess energy generated during sunny periods for later use. This won’t increase the output of the solar power station, but it will help utilize the energy it produces as efficiently as possible. ‍

Professional inspection. It’s advisable to periodically consult experts for system maintenance. They can identify and fix any issues that users might not notice.

So, solar panels do work in winter. And while they may not generate as much energy as they do in spring and summer, there is still the potential to meet half of a home’s electricity needs if measures are taken to keep the photovoltaic cells in top condition.