Identifying electrical load for stand-alone PV system sizing

PV system

PV modules are used in solar panels systems, also known as solar power systems, which are renewable energy systems that use sunlight to generate electricity. The electricity produced can be coupled with one or more additional electricity producers, more renewable energy sources, or stored or consumed directly. It can also be fed back into the system. A solar photovoltaic system is a reliable and environmentally friendly source of electricity that may be used for a variety of purposes, including homes, businesses, farms, and livestock. 

solar panels

Components of stand-alone photovoltaic system

The various parts of a solar PV system should be chosen based on the uses, site location, and system type. The main parts are:

Solar PV Module

Solar cells, a type of diode that produces energy when light, form a solar PV module.  To give more energy, multiple modules are connected in parallel or series. To produce the most power, the panels must be angled toward the sun. Some models also use trackers that watch the sun’s movement.

Solar charge controller

The batteries in a system need to be correctly charged and maintained at a high charge level for it to function well and last a long period. The main task of this equipment in a photovoltaic system is to regulate the current and voltage to properly manage the charge from the PV array into the battery bank. To avoid overcharging and over-discharging, the charge controller recognizes the batteries’ state of charge and adjusts the voltage and current supplied to them. The structure of the solar charge controller incorporates a multitude of technologies. 


An off-grid or standalone solar PV system stores solar energy in batteries for usage as needed. A battery is a collection of electrochemical cells that may operate loads that are linked to them by storing electrical charge as chemical energy through reversible chemical reactions. Batteries are connected to create a battery bank that generates a desired voltage and stores a certain capacity, much like PV arrays. Days of autonomy are a crucial component to take into account when building a battery-based solar system since they directly impact the size of the battery bank. Since deep discharge batteries supply energy without harming or reducing the life of the cells, they are employed in solar electric systems.


An inverter, also known as a “power conditioning unit,” is a crucial part of a photovoltaic system, as it is the point at which the AC appliances—which require an alternate current power source—are connected. The choice of inverter will rely on whether it is going to be a stand-alone unit or a component of a grid-connected system.

Identifying electrical load for stand-alone PV system sizing

Before sizing the PV system, it’s important to identify the inherent losses present in the whole system. For example, shading, reflection due to the angle of incidence, dust, degradation (aging), temperature effects, etc. can reduce the input energy of PV panels.

Make an Energy Audit and Determine the Need for Power

The decision-making process of a stand-alone system needs to begin with the load requirements. To calculate energy/day, first determine how much power each AC electrical load requires. Then, multiply that value by the average number of hours it operates on every day (Wh/day). An effective tool for creating such analysis is a spreadsheet.  

PV system

A review of the site is necessary to assess whether a solar system is feasible. Keep an eye out for any issues with shading and installation. Think about potential solar module locations at a particular location. Take into account the impact of wind or snow loading on the arrays, installation concerns, and maintenance concerns down the road. 

Calculate the Size of the PV Array 

The estimated resource(s), power consumption, and estimated efficiency can all be used to calculate the array’s size. This efficiency is caused by system losses including inverters, cabling, battery charging expenses, and circumstances that deviate from the quoted test parameters (such as temperature or irradiance). It does not account for the fundamental inefficiency of PV modules in transforming sunlight into power.

Determine the Needs for Batteries and Cabling 

Calculate the necessary wire size based on the original system design. When the voltage increases, the current (and hence the necessary wire size) decreases for a given power. Smaller diameter wire often has a lower cost but a lower current rating and a higher voltage drop. The size of the wire is usually chosen so that voltage dips fall between 2% and 3%; however, while calculating wiring requirements, applicable codes should be reviewed.

Choose the Elements

The components are chosen once the system has been examined. Mechanical and electrical hardware components for the system are also needed. These involve conduit and wire, disconnect switches, racks, connections, surge arrestors, mounting hardware, and other elements.

Examine the layout

Following completion, the design needs to be examined to make sure all components are functioning within their intended parameters and that the system’s requirements have been satisfied.

Before any work is done, plans should be submitted to the relevant government agencies for permissions and licenses after the design review is finished.


Photovoltaic (PV) systems, often known as PV systems, use semiconductor materials to convert solar radiation into electricity. To function, a photovoltaic system does not require direct sunshine. On cloudy and wet days, it can additionally produce power by the reflection of sunlight. PV systems can be constructed to be either grid-connected or stand-alone. You can contact Variate Solar to learn more about PV systems and how they work.

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