Solar panels will still work, generating electricity even when they are partially shaded. However, if an object entirely blocks them, the solar panel will stop generating electricity. Sometimes, even if the color doesn't completely block the solar panel, it may make power generation.
To understand how this works, we have to dig further into the effect of shadings on solar energy production, the solar panels' elements, and how they work when colors are found.
Shadings And Solar Irradiance
Solar radiation is usually expressed as the sum of two elements. The first is known as Direct Normal Irradiance (DNI). It represents the irradiance (a power obtained from solar energy by square meter) on a surface perpendicular to the sun. In other words, it is associated with solar radiation, which directly affects the solar panels.
The second element is referred to as DHI (Diffuse Horizontal Irradiance). The idea is associated with solar radiation reflected by lakes, clouds, or mountains that impact the solar panels.
There are two chief types of shadings. One type is known as far-shadings, and the other kind is known as near-shadings.
Far-shadings (also referred to as horizon shadings) refer to the declines in solar radiation because of shadings brought on by large objects such as mountains, valleys, or large buildings. Far-shadings are measured as reductions in DHI.
Near shadings are nearby objects such as walls, trees, chimneys, antennas, homes, or other modules that cause shadings on the solar panel. These are quantified as reductions in DNI and are the most critical ones.
Will My Solar Panels Create Electricity on Cloudy Days?
The short response to this question is yes.
Clouds decrease the amount of sun, but they significantly lower the natural part of solar radiation. Based on the concepts that we explained before, they dramatically reduce the amount of DNI that reaches your solar panels.
However, regardless of the cloudy day, we could still see the sun.
That is since the DHI part is still present on cloudy days. Thus, your solar panels will still produce electricity using the DHI part of solar radiation. The only difference is they will indeed have less power than on sunny days.
The Importance Of Near Shadings In Solar Panels
Once an object causes colors in a solar panel, the effect lowers the entire series's power output (set of solar panels configured in series). The barrier reduces the number of photons absorbed by the module.
At the same time, when a solar panel is partly shaded, then the current is reduced. But if we have a series of modules and one of these is partially shaded, then the entire string must reduce its current or power output since they're configured in series. That's a physics law that unfortunately can't be avoided.
Now, what happens when a module is shaded?
Bypass Diodes and Solar Panels
To increase the energy output in colors, solar panel manufacturers chose to include bypass diodes from the junction box. Bypass diodes are electronic systems that will run if there are partial shadings in a module.
With the Bypass diodes contained, the partly shaded module will still create power, only at a lower amount. As bypass diodes can be costly, solar panel companies tend to set a set of cells into one bypass diode and put three bypass diodes on the panel's junction box.
That way, every time a sector or corner of this module is shaded, a similar bypass diode will block the creation of the industry of cells. However, it will still enable the power production from the other two bypass diodes.
Otherwise, if a single solar panel in an array of modules is partly obscured, then the bypass diodes will let the current flow in the other modules based on the maximum current that the shaded module could create. Additionally, bypass diodes also help avoid hot spots that may severely damage the solar panels.
Bypass Diodes decrease the effect of near-shadings on panels and enable them to keep generating power in the presence of colors. However, near-shadings continue to be entirely undesirable for the performance of a PV system.
That's why your solar installer should design the system appropriately to decrease the effect of shadings. They must measure the sealing losses to be lower than 10% annually in simulation applications.
Remarkable Solutions From The Industry To Mitigate The Effect Of Shadings
To fight against conditions where shadings can't be avoided, the industry has come out with various solutions:
The first and perhaps most reliable ones for shading conditions are the module-level power electronics (MLPE) such as DC power optimizers from SolarEdge, microinverters from Enphase, or Tigo Energy power optimization in each module is independent. To put it differently, shadings on a single panel does not affect the others.
String Or Central Inverters
Another factor that has to be considered when shadings are found on the solar array is the maximum power point (MPP) monitoring.
When solar panels are shaded, the I/V curve of this series loses its standard form, and two maximum power points appear in turn: International MPP and Local MPP.
Regular Inverters could pick the LMPP as the curve's maximum operating point since their search range is limited. But, great options from inverter companies like Fronius and SMA maximize the power output of the array in colours by choosing the performance point at GMPP due to this SMA OptiTrac Global Peak attribute the Dynamic Peak Manager form Fronius.
Solar Panel Innovation
Another great solution that enables maximizing energy generation in colours is the Panasonic solar panel layout.
The Panasonic HIT, N330/N325 solar modules are the single ones in the market that include four bypass diodes. These reduce the number of solar cells, which could unnecessarily eliminate production in the presence of shades. Additionally, it maximizes the energy which the other Non-shaded modules can produce too.