PV systems can be small and very simple, consisting of just a PV module and DC load. On the other hand, PV systems can also be built as large power plants with a peak power of several MW: these are connected to the electricity grid. Many systems are placed on residential homes. When a whole house or building needs to be powered and is not connected to the electricity grid, the PV system must be operational day and night, It may also have to feed both Ac and Dc loads, have reserve power, and may even include a backup.
Depending on the system configurations, we can distinguish three main types of PV systems:

  • Stand-alone/Off-Grid Systems
  • Grid Connected Systems
  • Hybrid Systems


Off-grid solar electricity is for homes that do not have access to grid electricity – i.e the house cannot be or chooses not to be supplied electricity from a power company.  These systems offer complete autonomy and independence from the national grid and power companies, meaning you never have an electricity bill. These panels generate electricity which is used to power your home and charge your batteries. The batteries allow you to store electricity for use at night or times of low production like cloudy days.

  • This kind of a system will allow a customer to go off the grid
  • However, these are the most expensive type as additional battery cost is incurred to provide a backup of up to 48 hours for a normal household or business functioning (including autonomy for a 1-2 rainy days)
  • This is the most common installation type for areas that have no grid connection but are not very useful for urban areas.
  • These systems are usually sized to not include air conditioning, as it is only a seasonal load. A larger system installed to meet peak summer demand will lead to wastage of power in the winters, making it un-economical
  • Savings from the system lead to a payback period of up to 10 years. After that, you get free power for 10 more years


Grid-connected Systems

Grid-connected PV systems have become increasingly popular for applications in the built environment. They are connected to the grid via inverters, which convert the DC power into AC electricity. The inverter is connected to the distribution board, from where the PV generated power is transferred into the electricity grid or to AC appliances. In principle, these systems do not require batteries, since they are connected to the grid, which acts as a buffer into which an oversupply of PV electricity is transported. The grid also supplies the consumer with electricity in times of insufficient PV power generations.

  • It is important to note that this type of system will not run if the grid is down and the diesel generator is also not running
  • For this type of system, solar power is always given preference over both grid and diesel. An intelligent solar inverter ensures that solar is first fully utilized and then remaining power requirement is drawn from the grid or diesel generator
  • Most systems being installed in Haryana for meeting obligations are also of this type.
  • This is the most economically viable system as there is no requirement to install a battery bank. For Gurgaon, we recommend this system for customers who already have 100% power backup. When you install this system, you will still need to run the diesel generator when the power goes off but your fuel consumption will be lower.


3. Hybrid Systems

These systems combine PV module with a complementary method of electricity generation such as a diesel, gas or wind generator. In order to optimise system the different methods of electricity generations, hybrid system typically require more sophisticated controls than stand-alone or grid-connected PV system. For example, in the case of a PV/diesel system, the diesel engine must be started when the battery reaches a given discharge level, and stopped when the battery reaches an adequate charging state. The backup generator can be used to recharge batteries only or to supply the load as well.

  • This type of system combines the benefits of both a grid tied system and an off-grid system. It is the most useful type of system for houses, bunglows, nursing homes and other smaller establishments. It acts like a home inverter.
  • It allows for the system to provide 6-7 hours of backup for part of the load during power cuts while still delivering the benefits of a grid-tied system.
  • These systems are usually sized to not include air conditioning and other seasonal induction loads. A larger system installed to meet peak summer demand will lead to wastage of power in the winters, making it un-economical
  • Perhaps one air-conditioner can be used on this system when the power goes out. It will just reduce the back-up hours to 4-5 hours. For running more A/Cs in a power cut, it is recommended that the customer use a diesel generator



 Photovoltaic (PV) modules make electricity from sunlight, and are marvelously simple, effective, and durable. They sit in the sun and, with no moving parts, can run your appliances, charge your batteries, or make energy for the utility grid.

A PV array is the energy collector—the solar “generator” and does so via the photovoltaic effect. Discovered in 1839 by French physicist Alexandre-Edmund Becquerel, the photovoltaic effect describes the way in which PV cells create electricity from the energy residing in photons of sunlight. When sunlight hits a PV cell, the cell absorbs some of the photons and the photons’ energy is transferred to an electron in the semiconductor material. With the energy from the photon, the electron can escape its usual position in the semiconductor atom to become part of the current in an electrical circuit.

Most PV cells fall into one of two basic categories:
  • Crystalline silicon  
  • Thin-film.

Crystalline silicon modules can be fashioned from either monocrystalline, multicrystalline, or ribbon silicon. Thin-film is a term encompassing a range of different technologies, including amorphous silicon, and a host of variations using other semiconductors like cadmium telluride or CIGS (copper indium gallium diselenide). Thin-film technology generates a lot of the current R&D chatter, but crystalline modules currently capture more than 80% of the marketplace.

To use the energy from the array, you may also need other components, such as inverters, charge controllers and batteries, which make up a solar-electric system. The components required are dependent on the system type design, that we will discuss in our next post.

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