Engr. Dr. Muhammad Nawaz Iqbal
A photovoltaic system for supplying energy to homes, businesses, or industries is made up of a solar array and a variety of other parts together known as the balance of system. The phrase “Balance of plant” q.v. is equivalent to this phrase. Traditional c-Si solar cells are enclosed in solar modules to shield them from the elements. These cells are often wired in series. The module is made up of an aluminum frame around the edge, a rear back sheet made of a weather- and fire-resistant substance, tempered glass as the cover, and a soft, flexible encapsulate. Solar modules form a string of modules, commonly referred to as a solar panel, when they are electrically connected and mounted on a supporting framework. A solar array is made up of one or more of these panels.
Under STC (standard test circumstances) or PTC (PVUSA test conditions), solar panels are commonly assessed in watts. Less than 100 watts to more than 400 watts are typical panel ratings. The panel ratings, measured in watts, kilowatts, or megawatts, are added to form the array rating. By using some formulae that relate the variations in the open-circuit voltage, the short-circuit current, and the maximum power to temperature changes, the temperature effect on solar modules is often assessed. Comprehensive experimental guidelines to calculate temperature coefficients are provided in this study.
In order to create a lamination, numerous solar cells are wired in series due to the low voltage of a single sun cell. The laminate is put together into a protected, waterproof shell to create a solar or photovoltaic module. Then, modules might be connected to create a photovoltaic array.
The electrical output of photovoltaic cells is quite sensitive to shade. Due to intrinsic “short-circuiting,” the output is drastically reduced when even a small piece of a cell, module, or array of parallel cells is shaded while the remaining portion is exposed to sunlight (the electrons reversing course through the shaded portion). The current (and thus power) created by a string of cells is constrained because, when connected in series, the current drawn from the string is no larger than the typically modest current that can flow through the shaded cell. One shaded cell can absorb the power of numerous other cells in the string due to the reverse voltage of a shaded cell being significantly greater than the forward voltage of an illuminated cell, which has a disproportionately negative impact on the output of the panel. For instance, at a high current level, a shaded cell may lose 8 volts rather than add 0.5 volts, absorbing the power generated by 16 other cells. Therefore, it’s crucial that a PV installation is not covered by trees or other obstacles. There are ways to reduce diode losses, but these methods also result in losses.
Radiation that comes from the sun is reflected, diffused, and direct. The percentage of incident solar irradiance that is absorbed by the cell is known as the absorption factor of a PV cell. The power of the sun is approximately 1 kW/m2 on the surface of the Earth to a plane that is perpendicular to the sun’s beams on a cloudless day when it is at its zenith. As a result, tracking the sun throughout the day with PV arrays dramatically improves energy harvesting. For PV arrays, fixed mounts that tilt the array and face due south in the northern hemisphere or due north in the southern hemisphere are more prevalent than tracking devices because they are more expensive and require maintenance. For a stand-alone system, the tilt angle from horizontal can be adjusted for the season, but if fixed, it should be set to provide optimal array output during the period of time with the highest electrical demand in a typical year. The tilt angle for maximizing the annual production of array energy is not always the same as the tilt angle for optimal module tilt. The optimization of a photovoltaic system for a particular location can be challenging because it must take into account factors like solar flux, soiling, and snow losses. Additionally, more recent research has demonstrated that spectrum impacts can affect the choice of the best photovoltaic material.
On some sort of mounting system which may be categorized as ground mount, roof mount, or pole mount modules are integrated into arrays. The modules are put on a sizable rack that is positioned on the ground for solar parks. For pitched roofs on structures, a wide variety of racks have been developed. Racks, bins, and building integrated solutions are employed for flat roofs. Pole-mounted solar panel racks can be either permanent or mobile; for further information, see Trackers below. When a pole has another object installed at the top, such as a light fixture or an antenna, side-of-pole mounts are appropriate.
A solar panel is tilted all day long by a solar tracking device. The panel is either pointed directly at the Sun or the brightest region of a partly cloudy sky, depending on the sort of tracking system being used. Depending on latitude, trackers significantly improve performance in the early morning and late afternoon, boosting the total amount of electricity produced by a system by roughly 20–25% for a single axis tracker and by 30% or more for a dual axis tracker. In areas that receive a lot of direct sunshine, trackers are useful. Tracking is of little or no benefit in diffuse light (i.e., when there is cloud cover or fog).
Using tracking systems can save enough energy for large systems to outweigh the complexity increase. The additional maintenance required for tracking is a significant drawback for very big systems. For flat panel and low-concentration solar systems, tracking is not necessary. Dual axis tracking is essential for photovoltaic systems with high concentrations. The trade-off between having more fixed solar panels and fewer tracking ones depends on pricing trends.
