Solar panels react differently to the operating temperature. The efficiency of a solar panel decreases as it increases above the ambient temperature. Each solar panel has a temperature coefficient (which is defined in datasheet of panels). The temperature coefficient represents the rate at which the panel will underperform at each increase in degree Celsius (°C). Most panels have a temperature coefficient of between -0.2% /°C to -0.5%/°C, when tested under standard laboratory conditions, where ambient temperature is set to 25°C. For example if the temperature coefficient of a particular type of panel is -0.5%, then for every 10C rise, the panel’s output power will reduce by 0.5%. [Source: Youtube] [Publisher: altE Store’s Educational Video Channel]
What would happen if the solar panels deployed in the system have different electrical characteristics?
When solar panels with different electrical characteristics, interconnected with each other are deployed in the system, it creates serious power losses & adversely affects the overall energy generation. These losses are referred as “Mismatch losses”. The current (Isc) in the string in which the panels are connected in series with each other, is limited to the lowest output current from any of the panel. Thus mismatch causes the lower output power from the string & the system efficiency and performance becomes lower.
The performance of the solar panel is affected by its tilt angle and orientation with respect to the horizontal plane. Orienting the solar panel in a direction and tilt to maximize its exposure to direct sunlight can ensure a better generation. The solar panel collects solar radiation most efficiently when the sun’s rays are perpendicular to the panel’s surface. Solar panels should always face south if the plant is in the northern hemisphere, or north if the plant is in the southern hemisphere & the tilt of the solar panels should be proportionate to the latitude of the plant site to optimize their power generation throughout the year. The installer of the plant analyses the optimum tilt & orientation before installing the solar plant. [Source: Youtube] [Publisher: altE Store’s Educational Video Channel]
Weather conditions are unlike in each location. As solar plants are installed around the world, solar panel manufacturers test their products to ensure that they are dust & storm resistant, salt mist & ammonia corrosion resistant, capable to withstand hail storms & heavy snow loads & extreme temperature variations. The junction box attached with the modules are made waterproof.
When one (or more) solar photovoltaic cells becomes faulty or provides no power due to shading, the current then flows through the solar bypass diode and prevents hot spots and losses in yield. When part of a photovoltaic panel is shaded, the shaded cells will not be able to produce as much current as of the unshaded cells. Since all cells are connected in series, the same amount of current must flow through every cell. The unshaded cells will force the shaded cells to pass more current. This causes the solar panel to heat up, have a severe power loss. As a result, those shaded solar cells become consumers of electricity instead of producers. The function of bypass diode is, when a cell or a panel becomes shaded its bypass diode becomes “forward biased” and begins to conduct current through itself. The effected portion of the solar panel is bypassed, thus drastically reducing the amount of local heating & current loss at the shaded area. [Source: Youtube] [Publisher: altE Store’s Educational Video Channel]
The solar panel efficiency or conversion efficiency is the percentage of the solar energy striking on the panel that is converted into usable electricity. Not all of the sunlight that reaches a photovoltaic cell is converted into electricity. When light strikes the surface of a solar cell, some photons are reflected, while others pass right through, some of the absorbed photons have their energy turned into heat & the remainder have the right amount of energy to separate electrons from their atomic bonds to produce charge carriers and electric current. Most solar panels provide an energy efficiency rating between 11 to 18 percent, which is the percentage of solar energy that is being converted into usable electricity. A solar panel specification sheet usually contains a panel efficiency value at Standard Test Conditions(cell temperature of 25°C and an irradiance of 1000 W/m2). The higher the efficiency rating, the less number of panels you’ll need to make up a system that meets your energy requirements. However, choosing a more efficient solar panel may not always be the most cost-effective decision available.
Shading has a huge impact on the performance of solar photovoltaic panels. Solar power plants generate electricity proportionate to the amount of sunlight they receive. Therefore, when a shadow is cast on panels due to any obstruction in the path of sunlight falling on the panels, the power output decreases substantially. In fact, the solar photovoltaic panels consist of a number of cells which are connected together into a series circuit. Because of this, the performance of the solar panel is significantly reduced even if a smallest section of the panel is in shade. Another issue from partial shading is overheating. Because of partial shading a part of the solar panel generates lower amount of energy as compared to the other non-shaded part. As the amount of power generated from shaded & non-shaded parts differs, it leads to overheating, hot-spot creation & causing irreversible damage of the cells, which in turn reduces the total power output of the solar panel. Depending on the location of the object, the shading may be seasonal or for a few hours each day resulting in fluctuations in the power. The performance of solar panels is affected by the shading effect due to trees, neighboring buildings, vegetation, poles and any other means. [Source: Youtube] [Publisher: altE Store’s Educational Video Channel]