Q1. What is a Solar PV System and how does it work?

PV, short for Photovoltaic, derives its name from the process of converting light (‘photo’) directly into electricity (‘voltaic’). Simply put, a Solar PV system is a power station that generates electricity from sunlight.

The main components of a Solar PV system are:

  • Solar Panels or Modules: Solar panels consist of a group of small cells made from semiconductor material. When the sun’s light falls on the modules, it excites the electrons, thereby creating direct current (DC).
  • Solar Inverter: The DC electricity goes into an inverter that converts it into alternating current (AC). We use AC for running our household or office or factory equipment.
  • Storage Battery (optional): The best use of solar energy is to consume it while it is being generated. If the requirement is to store this power and consume it in the non-sunny hours, then solar energy can be stored in batteries for later consumption.

What is the difference between Solar PV and Solar Thermal?
The majority of solar energy, coming to our earth through the sun rays, is in the form of ‘light’ and ‘heat’. A Solar PV system uses the ‘light’ energy and converts it into electricity, which can then be used to run electrical equipment or charge batteries. A Solar Thermal system uses the ‘heat’ energy of the sun where a solar collector captures this heat or thermal energy and uses it to heat water or air.

Which technology is suitable for me?
Both Solar PV and Solar Thermal are suitable for you. If you need to run electrical and electronic equipment like lights, fans, TVs, computers, etc., Solar PV is the right solution for you. However, if you require a solution for water heating in your bathrooms or kitchens or swimming pools or for space heating, drying, cooling, etc., a solar thermal is more suitable.

Q2. Does a Solar PV system produce same energy output throughout the day?

Since Solar PV works on the basis of the intensity of sunlight it gets, your solar system typically wakes up at around 6am in the morning and goes to sleep at about 6 or 7pm in the evening. The energy output increases gradually and peaks at around noon and then gradually decreases as the Sun starts setting. But since the solar energy produced integrates either with your existing electrical connection or with your batteries, the running of your electrical equipment is not impacted. Moreover, if your Solar PV system is designed well, all your electrical equipment is totally safe.

What happens on cloudy days?
Solar PV system needs light to generate electricity. If Sunlight is low, as on a cloudy day, the solar system still generates electricity but the generation is lower. This reduced generation, however, may not create any disruptions for you. If you have a grid-connected Solar PV system, electricity will be automatically sourced from the grid in case Solar PV generates less. In case of an off-grid system with battery backup, energy will be sourced from the storage battery. 

What if I am not at home?
When you are not at home, your solar system continues to work and run any equipment that may be switched on such as refrigerators, security systems, etc. In case your energy consumption is less than the solar system’s generation, the excess energy will be fed to the grid. To avail this feature, you should opt for Net Metering.

Q3. What factors are important to consider when planning to go solar?

When planning to go solar, it is important to consider:

  • How much of your energy needs can you meet with solar?
  • How much can you save by going solar?
  • Do you have enough shadow-free space (land or roof)?
  • How much do you want to invest in your solar PV system?

Every Solar PV system is customized based on your site conditions. Therefore, you need a fair assessment of your energy requirements, site conditions and the solar energy generation potential at your site which would directly impact your savings.

How much space is required for Solar PV system?
A 1 kW rooftop system generally requires 10 to 12 sq. meters (110 to 130 square feet). Based on the space available, you can fulfil your entire electricity requirement through solar.
Solar systems are modular in nature and you can increase your system size anytime if your energy needs go up.

How much energy can be generated from my solar system?
Solar Power generation depends upon several factors like location, orientation of roof/ land, shadowing objects, ambient temperature, solar system quality, etc. Considering all of the above factors, typically, in a sunny area, a 1 kW system generates  4.0 to 4.5 units (kWh) which can run 4 lights (420W), 2 fans (275W), 1 TV (80W) and 1 refrigerator (150W) for 10 hours.

Q4. Can solar be my sole energy source?
Technically speaking, yes, if batteries are used. But practically, if grid power is available, then it is recommended to use solar in combination with grid. Solar PV can be integrated with your existing power sources (like grid power, inverter, diesel generator, etc.) in such a manner that the first priority is automatically always given to the solar power to be consumed first. However, if you are using Solar PV for night time usage or in a remote location, it is quite common to have Solar systems which are battery-backed.

Should I reduce my existing sanctioned load if I decide to go solar?
The Sun and therefore solar power is available only during the day. Therefore, to cater to your night time load it is recommended not to reduce your existing sanctioned load. The Powertech Solar Calculator shows your accurate savings potential considering all such factors.

What are my monthly savings?
Installing a solar PV system should lead to significant savings in your monthly electricity bill. The savings would depend on your location, consumer category and energy consumption pattern. As a thumb rule, the higher your tariff and the proportion of energy consumption during the day, the more are your savings. Check your monthly & lifetime savings on http://www.powertechsolar.in/solar-calculator/

Q5. What is the life and reliability of a Solar PV System?
Solar PV is a highly proven and reliable technology and have been in use since 1950s. A PV system that is designed, installed, and maintained well will operate for 25 years or even more than 25 years. The Inverters, which are an integral part of a Solar PV system, may need a replacement once in the 25 years lifetime of the system. Moreover, since there are no moving parts (unless you are using tracking devices to move modules tilt with the movement of the Sun), there is practically negligible wear and tear.

Do I get any guarantees or warranties?
The Solar PV modules are backed by suppliers’ guarantee of 25 years or more. In fact, the modules have been known to generate electricity even up to 40 years.

Do Solar PV panels degrade in performance with time?
Solar panels age with you, though at a much lower pace. It is usual to see a very small degradation in energy output with time which is due to the very nature of the solar module technology. Generally, annual degradation of modules is in the range of 0.5% to 0.7%. However, in the first year of your installation, this degradation may be higher.