Solar panels are comprised of thin silicon wafers or cells connected in series to boost the voltage of the array of silicon wafers. These wafers are mounted on a flat backing material to help support the silicon and assist with heat dispersion. The solar cells are then covered in tempered glass of transparent thermoplastics such as Plexiglas®.
Some solar panels are flexible and can be mounted on slightly curved surfaces such as the decks of sailboats. The slight curvature of solar panels can also follow the sun’s arc for a more extended period each day. Flexible solar panels are also significantly lighter than conventional ones.
The solar panel will remain functional for as long as the integrity of the crystalline silicon cells and connecting circuitry is not compromised. Solar panel efficiency is dependent on the following factors:
- Monocrystalline Vs. Polycrystalline silicon wafers
- Amount of productive solar radiation available at each location
- The adequate ventilation of the solar panel to dissipate heat
- The orientation of the solar panel with respect to the sun’s incident rays
Let’s look at ways to optimize the amount of solar energy generated in the available space at your location.
Why Were Thinner Flexible Solar Panels Developed?
In many off-grid applications, the space available to deploy solar panels is less than ideal and requires that solar panels of odd shapes and the ability to curve are needed. The horizontal surfaces on a sailboat, an RV, or camper roof are often curved to reduce wind resistance.
Designers will firstly consider aerodynamics when designing vehicles. The car’s mass is also critical to making overcoming gravitational effects less energy demanding. This leaves the cars with sleek curved lines and requires that elements like the windows be curved to fit the vehicle’s lines.
We do not design yachts and cars to be ideal for mounting solar panels as their primary mode of propulsion is not solar energy. Even on solar-powered EVs, the vehicle’s drag coefficient has to be as low as possible.
Solar panels encapsulated in thermoplastics such as Plexiglas® are much lighter and tougher than conventional solar panels. These panels can also withstand a limited amount of flexing and can thus be mounted on slightly curved surfaces.
Unlike conventional solar panels, the flexible solar panels have to be glued down onto the curved surface and thus lose the ability to ventilate and cool from below. This lack of ventilation will cause the solar panel to retain heat for longer and inhibit its efficiency.
Flexible solar panels can be mounted to a curved aluminum framework on roofs of ground-mounted arrays, but this is an unnecessary complication for a minimal gain in solar generation.
It is better to buy the conventional 60-cell 20V rigid solar panels for large roofs or ground-mounted arrays for grid-tied applications. This type of solar panel is the most widely available and has the lowest cost per kW of power generated.
Why Are Curved Solar Panels More Expensive Than Flat Panels?
Cutting solid silicon ingots into thin wafers is complicated with a high degree of waste. Cutting the silicon crystals with curvature is more complex and generates even higher cutting waste. The cost of the curved silicon wafers will be too high and offset any likely energy gains.
Solar panels are either monocrystalline or polycrystalline silicon crystals of very high purity. The silicon is melted and allowed to cool into a solid crystal ingot. The ingots are thermally treated to relieve internal stresses before being cut into thin wafers using diamond-tipped blades.
Due to silicon crystals’ hard and brittle nature, they are susceptible to fracturing and cracking during the cutting and polishing processes. The cost of the end product is also a function of how much waste is generated during production.
Trying to cut the silicon wafers into slightly curved slices to build a solar array of cells with a slight curvature will increase the amount of cutting waste, and the wafers will most likely have to be thicker.
It is easier to cut the silicon wafers as thin and flat as possible and then mount them in slightly flexible sandwich construction using a strong transparent thermoplastic like Plexiglas®.
How To Optimize The Solar Radiation On Your Array?
The angle of tilt of the earth to the orbital plane around the sun is 23 degrees. The point of installation of a solar panel will also determine at which angle the solar panel will be best oriented towards the sun to receive maximum solar radiation throughout the year.
There are two simple methods to calculate the best summer and winter angles of orientation of your solar panels to the sun. Firstly, determine the latitude of your solar installation.
To calculate the optimum tilt angle for the winter, add 15 degrees to your latitude. For calculating the optimum tilt angle for summer, subtract 15 degrees from your latitude. If you are in the northern hemisphere, your solar panels will need to be south-facing; if you are in the southern hemisphere, your panels must be north-facing.
If your northern latitude is 34 degrees, the optimum tilt angle during winter will be 34 plus 15 degrees or 49 degrees. Your optimal angle will be 34 degrees, minus 15 or 19 degrees in summer.
With these two setting angles, you will be able to get the optimal angle to the incident rays from the sun, only requiring the angular adjustments to be done twice per annum. There are sun-tracking solar array systems, but they are pretty expensive and complicated to install and maintain.
Keep your solar panels clean of dust and debris, and ensure no shade falls on the array from 9 am to 4 pm daily. These simple maintenance measures will give you a far more significant gain in solar panel efficiency than having curved solar panels.
Ensure you have sufficient solar panels to provide more than 120% of your power requirements. Solar panels are only 23% efficient at converting solar energy to electrical power.
Further efficiency losses are due to voltage drop due to the length of solar cables and inverter, battery, or solar charger inefficiency.