System Planning and Construction for Solar Photovoltaics

Energy is essential in today’s modern world, as it is used in many different contexts, including but not limited to manufacturing, heating, transportation, agriculture, lighting, and so on. Coal, petroleum products, natural gas, and other nonrenewable energy sources provide the bulk of the world’s energy demands. But, our environment has been severely impacted by the exploitation of these resources.

It’s also worth noting that this particular type of energy source is not distributed equally around the globe. For commodities like crude oil, whose market value is tied to the cost of producing and extracting it from its reservoirs, this production and extraction risk adds a layer of uncertainty to the price. Renewable energy sources have been increasingly popular in recent years due to the scarcity of conventional energy options.

When discussing sustainable energy options, solar power has been front and center. There is an abundance of it, and it might provide enough power for everyone on Earth. This article will take a quick look at the steps involved in developing a design for and ultimately constructing a PV system that can generate electricity independently. Let’s start with some solar photovoltaic system fundamentals.

  • MOUNTING STRUCTURES

PV arrays must be installed on a sturdy, long-lasting construction that can keep them up for decades despite the elements. The angle at which these structures tilt the PV array is set according to the local latitude, the building’s orientation, and the required electrical load. Modules in the northern latitudes are oriented with their long axis due south, and their slant angle corresponds to the local latitude to maximize annual energy production. 

Because it is sturdy, flexible, and simple to build and install, rack mounting has become the standard. Modernization efforts result in improved techniques that cost less without sacrificing quality.

Tracking mechanisms mechanically shift solar panels on ground-mounted PV arrays to follow the sun’s path across the sky, increasing energy production and the system’s return on investment. In most cases, east-to-west tracking is the primary function of a one-axis tracker. Modules can be directed at the sun all day long with the help of two-axis trackers. There will always be higher initial expenses associated with tracking and ongoing costs associated with maintaining more complex systems. In recent years, tracking has become more financially viable for ground-based devices than before.

  • BUILDING-INTEGRATED PV

In addition to their more typical placement in specially designed mounting structures, photovoltaic panels can be incorporated into roofing, windows, and even fa├žades. The term “building-integrated PV” is used to describe these methods. By reusing existing building infrastructure, such as electrical wiring and roofs, the cost of installing solar panels can be reduced, and material and supply chain efficiency can be increased. Building-integrated photovoltaic systems (BIPV) have the potential to supply electricity for direct current building systems, such as LED lighting, processors, detectors, and motors, and to facilitate grid-integrated optimal building applications, such as electric vehicle charging. 

There are still technical and commercial hurdles to overcome before BIPV systems can replace conventional mounting structures and construction materials in general use. Still, their exceptional value makes them an attractive option.

  • INVERTERS

The electrical energy produced by solar photovoltaic modules must be converted from direct current (DC) to alternating current (AC) before it can be used for local transmission or by most household appliances. Module-level inverters, or microinverters, are used in PV systems to transform the electricity produced by the modules. In most cases, a single inverter will be less expensive and easier to cool and service. To account for the possibility of specific modules being shaded, the microinverter enables individual control of each panel. Throughout a PV array’s estimated 25-year lifespan, at least one inverter will need to be replaced.

Smart inverters, also known as high-tech inverters, are two-way devices that can exchange data with the power company. Automatically or through remote connection with utility operators, it can aid in balancing supply and demand. Utilities can save money, keep the grid stable, and reduce power outages if given this information.

  • STORAGE

Batteries make it possible to store the energy produced by solar photovoltaic panels so that they can be used later, such as at night or when clouds block the sun from reaching the panels. Batteries have a wide variety of applications beyond the house and are becoming increasingly crucial to the functioning of the utility sector. Solar power that is fed back into the grid by customers can be stored in batteries and sold back to them at a later time. More widespread adoption of batteries will aid in updating and consolidating the United States’ power infrastructure.

Preparation for a Single Pv System

Evaluating the site, doing a survey, and calculating the potential for solar power:

The output of a PV system varies significantly with both time of day and location, making it crucial to pick the right spot for a solitary PV installation. Accordingly, the following factors are essential when evaluating potential installation sites.

  • Minimum Shade

Whether a rooftop or a ground-based location is chosen, no obstructions must prevent sunlight from reaching the solar panels. Also, check that there isn’t any nearby building work that could add to the shading issue.

  • Exposed Area

To estimate the size and number of PV panels needed to create the required power output for the load, it is necessary to know the site’s surface area where the installation is planned. Inverters, converters, and battery banks can all be better prepared with this information.

  • Rooftop

The rooftop installation process necessitates knowledge of the roof material and layout. The tilt angle of a roof must be determined, and the appropriate mounting must be employed if the panels receive the maximum possible amount of solar radiation; this means that the radiation direction must be tangent to the PV panel or at least very near to 90 degrees.

  • Routes

The connections connecting the inverter, battery bank, charge controller, and photovoltaic array should be routed to maximize efficiency and reduce voltage loss. The system’s efficiency and affordability must be prioritized, but the designer must make a choice.

The solar energy assessment of the preferred location is crucial for generating power output estimation. The amount of solar radiation that reaches a given location over a specific period is known as insolation. 

One can use a pyranometer to obtain this information, although it is not strictly essential because one can get insolation information from any local weather station. Kilowatt-hours per square meter per day and Daily Peak Sun Hours are two units of measurement that can be used to analyze solar energy data.

As a shortcut, most people utilize the time of day when the sun is at its highest. Don’t get the “Mean Sunshine Hours” and “Peak Sun Hours” numbers mixed up that you’d obtain from the weather station. The Peak sun hours are the actual quantity of energy received in KWh/m2/day, whereas the “Mean sunshine hours” show the number of hours the sunshine was present. 

To ensure the system functions reliably even when the sun is weakest due to unfavorable weather, the lowest mean daily insolation value should be used throughout all months in a given period.

Things to think about when installing a PV system on its own

  • Forecasting Energy Needs

The required power output must determine the size of a stand-alone PV system. When estimating energy needs, it’s essential to consider that different appliances have varied loads and run for different amounts of time. To calculate how much energy a load uses, multiply its wattage (W) by the number of hours it is on. 

The peak day of energy use should be considered while designing a system. A system’s dependability can be ensured by creating it to handle the worst-case scenario. If the system can handle the maximum demand, it will also be able to take the minimum. But, the system’s total cost will rise if it is designed to accommodate the maximum possible demand. However, the system will operate at 100% capacity during the foremost need. We’ll have to prioritize the system’s reliability over its low cost.

  • Ratings of converter and inverter 

Specifying the input voltage and current rating is essential for selecting the suitable inverter. The inverter’s ability to manage both the load voltage and the current drawn from the battery bank determines the voltage at which it will convert the DC power from the system. The inverter’s power rating is determined by the total load connected to the system.

For example, if the power operating load is 2.5 kVA, then an inverter with a power handling capability 20-30% larger than that should be selected from the market. The motor load, in this situation, should be three to five times greater than the required power output of the device in question. The charge controller has current and voltage ratings to match the converter. The PV module short-circuit current rating determines the system’s current capacity. The voltage level corresponds to the standard battery voltage.

  • Calculating the Appropriate Size of Your Converter And Charge Regulator

The PV panels’ maximum short-circuit current must be 125% of the charge controller’s rated capacity. Simply put, it needs to be 25% higher than the current drawn by a solar panel in a short circuit.

  • Inverter Sizing

Due to losses and efficiency issues, the inverter should be 25% larger than the entire load. That is to say, its wattage rating should be 125% more than the whole load expected to be placed on it.

  • Daily Energy Supplied to Inverter

In this scenario, let’s assume that the load has an average daily energy usage of 2700 Wh. The energy provided to the inverter must be more than the energy utilized by the load to compensate for the losses in the inverter, which are to be expected given the inverter’s efficiency.

  • System Voltage

The voltage at which an inverter is fed is called the system voltage. It’s the total voltage of the battery pack as well. The system voltage is determined by the individual voltage level, the line current, the maximum permissible voltage drop, and the energy losses in the cable. The system voltage will match the battery voltage, typically 12 V. 

But voltages above 12 V should be in 12 V increments. Since power loss and voltage drop in a cable are inversely proportional to current, raising the system voltage is one way to minimize these problems. By doing so, we can add more batteries to the series circuit. This results in a trade-off between power loss and overall system voltage.

  • Sizing of the PV Array

There is a wide range of output power from the various-sized PV modules on the market. Using the lowest mean daily insolation during peak sun hours is one of the most prevalent ways to size the PV array.

  • Cable Diameter Dimensions

Several parameters, including the maximum current carrying capability, determine the appropriate cable size. There should be little to no voltage drop and very little resistance. Since these wires will be installed outside, they must be weatherproof and UV-resistant.

Since voltage drop is a problem in low-voltage systems, the cable must function with a voltage drop of less than 2 percent. Energy is wasted, and accidents may occur if the wires are too large.

Conclusion

An independent PV system is an excellent method to harness the clean, renewable power of the sun. Its installation and setup are made simple and trustworthy for power needs of any size. Even in the most remote parts of the earth, this method might make electricity accessible. It frees the customer from the utility and other energy suppliers like coal, natural gas, etc.

There would be no lasting harm to the environment from such a system, and it would continue to supply energy for years after it was set up. To meet our current and future demands for clean, sustainable energy, the aforementioned systematic planning and implementation are helpful guides.

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