People around the globe are shifting towards renewable sources of energy to meet their power needs. While solar power is a cost-efficient and effective way to meet the world’s power requirements, the important factor to consider is whether solar panels can really make sense in the areas of shade.
Do solar panel works in shade? Yes, Solar panels can work in shaded areas as well as during cloudy days but their output power capacity is compromised due to less exposure to sunlight. Certain solutions like solar panel design and roof orientation can help prevent an excessive power loss caused due to less sunlight exposure.
People generally assume that solar panels are of no use unless exposed to bright sunlight. However, this is a misconception and modern solar panels are capable enough to work even in poor light conditions. Still, there is a need to analyze the effect of shade on the solar panel as well as how you can minimize it and what sort of panel design is right for fulfilling your power needs given the shading conditions of your location. In this article, we will examine the sources of shading, its effects on the efficiency of the solar panel and how the efficiency losses can be mitigated.
What causes shading and does it affect solar panels?
As discussed above, shading plays a very crucial part in the efficiency of the solar panels. There are different sources that can be a cause of shade on solar panels. The most common sources are listed below:
- Trees – Many residential areas that are located in green spaces face shading issues. The trees near the solar panel setups can cause shading issues by encroaching the setups.
- Clouds – Weather plays a very important factor in determining the amount of sunlight reaching the solar panels. Clouds do not completely block the sunlight but they do reduce the amount of sunlight exposure on to the panel which reduces the amount of solar energy harvested to electricity
- Other Panels – Solar panels can also be shaded by neighboring panels especially when there are ground installations. If incorrectly installed, nearby panels can caste a shade on the panels in the same system.
- Roof and Buildings – Panels are greatly affected by the roofs and surrounding buildings if the system is located in an overly populated area. Based on the peak hours of the day, surrounding buildings and roofs can block sunlight to the panels
Now that we have looked at the sources of shading lets discuss the impact it has on the solar panels.
Decrease in Efficiency-A solar panel consists of the solar cells. Those solar cells which are covered in shade will stop working so if 50% of the panel’s solar cells are under shade, then solar panel’s efficiency will be reduced to half but shading does not completely halt the electricity production. Most of the modern solar panels can work even in poor light conditions but at the expense of efficiency. The power loss varies based on the amount of shade the panels are facing.
If you cannot avoid shade, then the best option is to use the shade tolerant solar cells like Uni-solar etc.
Shortens life span –When some of the solar cells in a solar panel are not working due to shading then other cells free of shade work harder in order to compensate the power losses. In this process, the unshaded solar cells might get overheated or burn out due to over performing. This reduces the lifetime of the solar panel and can result in permanent damage to the PV system. Bypass diodes can be used to minimize the effect of partial shading on the solar panel.
Do solar panels need direct sunlight to make sense?
A lot of people wonder whether direct sunlight is needed for solar to make it a feasible option economically or not. Yes, indeed, the more sun exposure there is, then more output gets generated from the panels. It is true that direct sunlight provides optimum conditions for the panel to operate however even in the cloudy weather, some of the light may still reach your solar panels to make them work.
It is estimated that a solar panel will be 40% less effective during cloudy weather conditions.
In a grid-tied solar panel, the excess amount of power generated during a sunny day, gets fed back to the utility grid in exchange of energy credits. This is done via a device known as a net meter which measures the electricity going to and from the grid. The energy credits can be utilized to draw power at night and on a cloudy day.
The term “Peak sun hours” refers to hours during which the intensity of sunlight is maximum, i.e., 1,000 watts per square meter. Peak sun hours provide an accurate description of how much energy your panels can produce in a day.
On average, the peak sun hours are between 3 to 4 hours a day.
How do you calculate how many sun-hours an area gets?
Solar map tools can be used to estimate the average amount of sun hours of a location however it only gives you the estimate based on longitude and latitude coordinates of a location. In order to get an accurate reading many other factors about a location should be taken into consideration before drawing any conclusions.
Some software tools like Aurora can use the satellite imagery of a location and estimate the sun hours based off that information alone. But these tools are not always 100% accurate and it takes a lot of time to learn how to use them if you’re not all that computer savvy.
Solar installation companies, on the other hand, should have their own proprietary software that can also provide an accurate estimation of sun hours of a location to its customers based on factors like roof orientation, shading, weather etc. Many other metrics can be estimated from the solar energy analysis of a location such as a target offset of solar energy and estimates of 20 to 30-year savings.
Solar companies usually provide an on-site investigation once you sign up to go solar with them. These companies have certified solar techs who uses a tool called “sun eye” to provide more accurate shading analysis of a location to ensure that the solar panel can meet the companies estimated amount of production on a particular location. If in the event it is determined that your location does have some shading issues, there are certain ways to optimize the solar panel productivity.
How can issues of shading be resolved to boost solar panel productivity?
Solar panel systems can be altered and modified in a number of different ways to overcome shading losses. Some of the common methods devised are as below:
- Stringing Arrangements – Modules in a solar panel system are connected in series to form strings that are connected in parallel to an inverter. The power output of a string can be brought down significantly if it has a shaded module in it. However, the output of a parallel string cannot be reduced by a shaded module in one string. Hence the system can be optimized by classifying shaded and unshaded modules into different strings. For example, in systems that are commonly deployed in the market or businesses, modules that receive shade can be grouped into one string while the remaining modules that receive no shade can be grouped into another string.
- Bypass Diodes – They are devices in a module in which the current can go past the regions of the module that are covered by shade. Utilization of the bypass diodes allows unshaded cell strings to allow current to flow through them. However, the drawback of using these devices is that we cannot benefit from the working from the solar cells which have been bypassed by the flowing current. Roughly, around 3 bypass diodes will be required for a panel having 60 solar cells.
- Module-level Power Electronics (MLPEs) – MLPEs are devices that are connected to each shaded solar panel module in a PV system to boost their power output by the use of maximum power point tracking. MLPEs commonly include DC optimizers and microinverters.
- DC Optimizers – DC optimizers tend to increase the power output of an individual solar module, by maintaining the performance of other modules as well, by changing the voltages and current at the output of a particular solar module. For instance, a DC optimizer will boost the output current of a shaded solar panel producing electricity with a lower current by decreasing its voltage so that the current through it is of the same value as the current flowing in the unshaded panels. This ensures that the same amount of power is produced by all the panels.
- Microinverters – The DC -AC conversion in each panel can be done by having each panel connected to a small inverter instead of having a single inverter for the entire system since all the modules will be connected in parallel and each microinverter will work at its MPPT, the functioning of other panels would not be affected. This will not let the efficiency of the panels be affected due to the shading effect of the panels.
- Ground Mount PV System– In Ground-mounted PV systems, the panel orientation can be optimized as well as there are no space constraints. They also have better ground clearance between the panel and the ground.
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