Solar panels usually generate DC electricity. A type that is useful and widely used across a variety of devices and appliances in our daily lives. Anything that uses a battery to power itself runs on DC electricity. Your Mobile Phone, your laptop, your wall clock, your TV and AC remotes, all work on DC electricity. However, we are also surrounded by AC appliances as well. Almost all of our home appliances including water pumps, Air Conditioners, fans, room heaters, induction cooktops, geysers, all work on AC electricity. There are certain devices that still take power from the wall outlet, but, run on DC electricity only. Anything that uses a power adaptor to convert AC power to DC can still be run using an appropriate DC power source like a battery. Even your car, the regular petrol or diesel, or the newest electricity cars, run on DC power.
As already highlighted earlier, Solar panels usually generate DC energy. In order to use in our day-to-day appliances, we need to convert this DC energy into AC energy. This requires a device called an inverter, that converts DC energy – sometimes stored in a battery, sometimes generated by an array or solar panels, into AC energy that can be used by our home appliances. You can still use a solar panel to run appliances, but, those won’t be your regular home appliances running on AC 110V or 220V, that your electricity company provides. You will be needing special appliances capable of running on DC.
Any such system that has a solar panel, an inverter, and sometimes battery/batteries to convert/store the electricity generated by Solar panels can be broadly categorized into On-Grid, Off-Grid and Hybrid solar power systems.
On-Grid/Grid-tied Solar power system is the simplest of all, which includes some solar panels, and an on-grid inverter that converts the DC electricity generated by solar panels into AC electricity, as the main components. These types of systems are usually installed with Net/Gross metering, a kind of arrangement between the consumer and the electricity distribution company (DISCOM) wherein the DISCOM allows the consumer having an active energy connection and an suitable solar power system to export surplus energy in the grid.
This sometimes helps the DISCOMS reduce the electricity shortage and thus the load-shedding when the power demand is very high. The consumers are, in return, allowed to offset the amount of energy they consumed from the grid, and the amount they exported to the grid. This is done via a separate energy meter that the DISCOM usually provides the consumer to record the total amount of energy they exported during a billing cycle. This also helps the consumers reduce their net electricity bills, and in a very few cases, earn money from the DISCOM, in cases where the Net energy exported to the grid exceeds that consumed. Different DISCOM’s across the world have different mechanisms about this. Some pay the consumer at the same rate they charge them for the energy consumed from the grid, some pay less, and a very few pay a bit more, usually to encourage wider adoption.
While there are clearly some advantages of an on-grid solar power system, all of is not rosy as it appears. There are some disadvantages of an on-grid solar power systems.
| Advantages | Disadvantages |
|---|
| Easiest to install | Can be comparatively expensive |
| Low parts count | Cannot be installed without an active grid connection |
| Allows for net/grid metering connections | Does not provide power in case of grid failure |
| Best conversion losses | No power-backup possible |
An Off-grid Solar power system is one where a grid supply is unavailable/unviable. Such a system uses an array of solar panels, a solar inverter or a normal inverter with a charge controller, a (set of) battery(ies). Such a system allows even houses in remote areas, completely cut-off from the grid, to be powered with the help of solar panels/ small wind-turbines. Such systems are designed keeping in mind a lot of things – The climate of the place, availability of sunlight, terrain suitable for installing solar panels, Power consumption, and the amount of battery backup required. These systems could be quite expensive to install and maintain as batteries are some of the most expensive components in this system, and the ones requiring most amount of maintenance.
| Advantages | Disadvantages |
|---|
| Scalable Power-backup option | Can be comparatively expensive |
| Does not need active grid supply | Limited by the installed battery capacity |
| Can be installed even in remote areas | Requires frequent maintenance/parts (battery) replacement |
| Reduces electricity costs | High Return on Investment (RoI) period |
A Hybrid Solar power system is a mix of an on-grid and an off-grid solar power system. With such a system, you can get the benefits of an on-grid inverter, like net/gross metering, as well as that of an off-grid solar power system, like possibility of a battery enabled power backup. Needless to say, this kind of system is comparatively costlier than the other two systems, since it includes a specialised inverter system that can act as an on-grid inverter to convert the DC electricity generated by the solar panels into AC electricity and also allows batteries to be connected to it to provide power backup in the event of a power outage. A hybrid solar power system has the advantage of being a one-device-fits-all your requirements.
| Advantages | Disadvantages |
|---|
| Versatile device that allows net/gross metering and power backup option | Is expensive when compared to On-Grid/Off-Grid solar power system |
| Can be a good choice for places with frequent power cuts | Requires frequent maintenance/parts (battery) replacement |
| Comparatively cheaper when considering both options (grid-tied and off-grid) separately | High Return on Investment (RoI) period |
With the above article, we hope that you now understand the basic difference between the three kinds of solar power setups - On-Grid, Off-Grid and Hybrid, and you will be able to make your purchase decisions with more understanding of the kind of setup you would like to install/get installed. This also comes in handy when you are building a system considering the huge amounts of investments right at the beginning.
Going Solar is the demand of the time. Power outages can occur anytime and anywhere. Even if you do not face frequent power cuts, the ever increasing power tariffs across the world - triggered by the increasing prices of the fossil fuels that are predominantly being used to generate a majority of our utility scale grid power. By going solar, you are saving money over a long period of time as most solar power setups return their initial investment in about 4-7 years, depending upon a variety of factors including the power tariff at your location, the kind of usage you put your system in, and also the size of the solar power system you have got installed. You are also doing your bit in saving the earth by reducing the amount of carbon dioxide generated as a result of burning of fossil fuels to generate power.
GO GREEN, GO SOLAR!