What type of solar power system do I need for my home?

This post aims to familiarize you with the basic workings of a solar power system. We will also look at the different types of solar power systems available for us to choose from. A basic understanding of such systems is extremely useful when deciding on the type that suits every individual household requirement and the benefit it brings in.

A quick recap

As discussed in our previous blog post, the basic principle behind a solar power system is pretty simple. Solar panels are usually made of silicon semiconductors, also known as photovoltaic cells (PV) absorb the sunlight that falls on its surface and produces electricity. A direct current(DC) is generated from the panel. You can use the generated power to run your home electrical appliances and motor, either directly or by converting it into alternating current (AC). The conversion from DC to AC is done by using a solar inverter. Depending on the type of solar power system installed and based on your amount of electricity used, the difference between power consumed and power generated i.e., excess power can be either stored in a battery or fed directly to the grid. In any case, the homeowner ultimately gets the benefit of cutting down on electricity bills, by consuming less or no electricity from the power grid or by earning credits from your electricity supplier.

So what are the types of solar power systems?

There are basically three types of solar power systems. 

On-grid also is known as the Grid-Tied system

This is the most common and widely used configuration. As the name suggests, your solar power system would be connected to the electricity grid. This is done to facilitate the export of excess power generated and also to complement during excess load requirements. The electricity that is being fed to the grid can be used by others in your (neighborhood or community) who share the same grid. One of the major benefits of installing such a system is that you are paid for the electricity your system feeds into the grid. The method of calculating the electricity bills on the basis of total power consumed from the grid and the total solar power fed into the grid from an independent household is called Net-Metering.

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Off-grid solar system

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This type of solar power systems are not connected to the grid. They work independently and you would typically connect external batteries to store the generated electricity. An off-grid solar system is designed in such a way that it can generate a sufficient amount of electricity throughout the year and have enough battery capacity to store the total household energy requirement even when there is less amount of sunlight. The off-grid systems have an additional cost of batteries included in the system when compared to on-grid systems. They are commonly used in areas that are frequently affected by power cuts and also areas that are away from the grid. A growing number of people are adopting solar power. This increased market consumption is a good sign that has reduced the costs of the overall components like solar panels, solar inverters, batteries, thereby making it more economical and affordable.

Hybrid solar power system

In simple words, is a combination of On-Grid and Off-Grid systems. The working principle of this system similar to that of the On-Grid solar system and has the facility to store the energy generated from the solar panels. This gives you the benefit of both the previous types. In the absence of solar power, grid power is used as a source of electricity to run the household appliances and charge the battery. This makes hybrid systems more flexible. The solar energy generated during the day, stored in the battery can be used during power cuts and night times. In the situation where the battery is completely drained out, power from the grid is automatically used.

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What is the concept behind ‘solar net-metering’ and ‘gross-metering?

When we hear about solar power systems, we often come across the concept called solar net-metering or solar gross-metering. Previously, we learned about how solar power systems work, the various types, as well as storing the generated energy into a battery or feed-in to the grid depending on the type of power system. Many countries and their various state governments, encourage individual houses to generate and supply electricity to the grid at fixed rates. They also offer an option of unit credits based on the total generated solar power and the consumed electricity from the grid in order to compute the final electricity bill.

What is solar net-metering and gross-metering?

  • The surplus energy generated is sent to the grid after individual household consumption. This thereby reduces the dependency of the household on the grid. The method of calculating the difference between total solar power generated and the total power consumed is called net-metering.
  • In the cases of solar farms or utility-grade solar power plants, where the entire amount of electricity generated by a solar power system is fed to the grid, the calculation of electricity exported to the grid and imported from the grid is called gross-metering.

In Net-Metering, individuals are provided with unit credits, whereas in the case of Gross-Metering, individuals or companies are paid with Feed-in-tariff (FIT) respectively.

In general, net-metering and gross-metering are done with a bi-directional meter that records the total energy sent to and received from the grid.

When it comes to a rooftop solar power system, often the electricity consumed by the individual household is less compared to the energy generated during the daytime. The difference between the total electricity produced and the total electricity consumed by the household is calculated with net-metering. The individual is billed for the ‘net’ electricity that has been used over the month. The amount is adjusted with the credits earned by exporting the electricity.

In the case of gross-metering, the individual/company is billed for the electricity used from the grid and the amount, in line with the feed-n tariff fixed by the government is paid by or paid to the individual. The net amount is usually credited to the registered individual or company account.

Advantages of net-metering and gross-metering

Below are some of the benefits realized by independent home-owners.

  • The concept encourages more individual homeowners to switch from conventional sources of energy to alternative sources of energy.
  • The relatively high initial costs of these systems are offset by earning financial credits and significantly lower electricity bills.
  • Due to the absence of batteries, the initial capital invested and the subsequent maintenance costs are considerably lower than off-grid systems.

The benefits of these systems are also useful for residential apartments or society at large.

  • They help in providing accurate information on the amount of electricity produced and how much is being used in a particular locality or commonly shared areas.
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Frequently Asked Questions about Solar Power System

There are fundamentally three main types of solar power systems that are commonly available. They are an On-Grid solar power system also known as grid tied, Off-Grid and hybrid solar power system. Each of them have their own pros and cons based on the user requirements like power export to grid or power back up etc.,

On-grid solar power systems are the most commonly used and cost effective type to install. It is designed to provide power to electrical appliances and also export the excess electricity to the grid at a unit rate defined by government and utility provider. As the name suggests, it works only when there is power in the grid.

Off-grid solar power systems are designed to work without main power grid and also to provide power backup with batteries. An off-grid solar system is designed in such a way that it can generate a sufficient amount of solar electricity throughout the year and have enough battery capacity to store the total household power needs.

In simple words, a hybrid solar power system is a combination of both On-Grid and Off-Grid systems. The working principle is similar to an on-grid solar system with an additional facility to store the electricity generated from the solar panels in batteries for use during power cuts, day and night times.

The surplus energy generated from solar power systems can be sent to the grid after individual household consumption. This method reduces the dependency of the household on the grid. The method of calculating the difference between total solar power generated and the total power consumed is called net-metering. Net-meters are typically provided by the main power supplier.

In the solar farms or utility-grade solar power plants, where the entire amount of electricity generated by a solar power system is fed to the grid, the calculation of electricity exported to the grid and imported from the grid is called gross-metering. In gross metering, the owners of the solar power plants are paid with Feed-in-tariff (FIT).

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