Solar panels convert solar energy or sunlight into direct current (DC) power by the photovoltaic (PV) effect.
All solar PV power systems work on this same basic principle.
The DC power thus generated may be stored in a battery or needs to be converted by a solar inverter into an alternating current (AC) power source, which is used to run various appliances or may be fed into the electricity grid for credits.
The three main types of solar PV power systems are :
On-grid - also known as a grid-tied or grid-connected
Off-grid - also known as a stand-alone
Hybrid - grid-connected system with battery storage
2. Off-Grid Solar Systems :
Off-grid solar PV systems generate power by converting sunlight to electricity.
These systems work independently of the grid (they are not connected to the grid). Instead they may be used to run appliances directly or have batteries which can store the solar power generated by the system.
Such a system usually consists of solar panels, battery, charge controller, grid box, inverter, mounting structure and balance of system materials. The system stores enough sunlight during the day to use during the day and keep available the excess power generated for use in the night.
These systems are self-sustaining and can provide power for critical loads in areas where the power outages are more in general or there is no grid connectivity available.
Applications :
Off-grid solar systems can facilitate independent, long-term and sustainable electricity generation in rural and remote areas.
A number of places in India face frequent power cuts due to power transmission, malfunctions, which can hamper operations of companies and public institutions. These are ideal cases for setting up an off-grid solar system.
Advantages :
These self-sustainable systems can work independently and do not rely on the grid.
They generate enough power that can be stored and used at night or when the power grid is down.
These are ideal for remote areas where there is no power access from the grid.
Grid failures and shutdowns will not affect your power supply.
Power Outages with Off-Grid Systems :
Your solar system is working independently from the power grid. If there's a bad storm or event that knocks out the power, your solar system can continue operating. You won't notice changes in your service or access to electricity.
Electricity Bills with an Off-Grid System :
If your PV system is not tied to a grid, you won't receive an electricity bill at all. However, even with no electric bill, off-grid systems are often more expensive because of the additional equipment like batteries that are needed to make it viable.
3. Hybrid Solar Systems :
Modern hybrid systems combine solar and battery storage in one and are now available in many different forms and configurations. Due to the decreasing cost of battery storage, systems that are already connected to the electricity grid can start taking advantage of battery storage as well. This means being able to store solar energy that is generated during the day and using it night. When the stored energy is depleted, the grid is there as a back-up, allowing consumers to have the best of both worlds. Hybrid systems are also able to charge the batteries using cheap off-peak electricity (usually after midnight to 6 am).
The battery bank : In a hybrid system once the solar power is used by the appliances in your property, any excess power will be sent to the battery bank. Once the battery bank is fully charged, it will stop receiving power from the solar system. The energy from the battery can then be discharged and used to power your home.
The meter and electricity grid : Depending on how your hybrid system is set up and whether your utility allows it, once your batteries are fully charged excess solar power not required by your appliances can be exported to the grid via your meter. When your solar system is not in use, and if you have drained the usable power in your batteries your appliances will then start drawing power from the grid.