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PV systems Types

PV systems can be small and very simple, consisting of just a PV module and load, as in the direct powering of a water pump motor which only needs to operate when the sun shines. 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
1. Stand-alone Systems
Stand-alone systems, which are also called off-grid systems, rely on solar power only. These systems can consist of the PV module and a load only or they can include batteries for energy storage. When using batteries charge controllers from the PV modules when they are fully charged, and may disconnect the load to prevent the batteries from being discharged below a certain limit. The batteries must have enough capacity to store the energy produced during day to be used at night and during periods of poor weather.


  • 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

2. Grid-connected Systems

grid-connected-systemGrid-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. In small systems such as those installed in residential homes, 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 the house. In principle, these systems don 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 house with electricity in times of insufficient PV power generations. However, more and more grid-connected systems also contain batteries in order to increase self- consumption, i.e the amount of PV-generated electricity that is consumed by the household.

  • 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

hybrid-pv-systemThese 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
  • Savings from the system lead to a payback period of up to 7 years. After that you get free power for 18 more years