How to choose the right solar PV system that best suits you?

Wanting to purchase a new Solar PV system?

Confused about the different types of Solar PV systems and what to purchase?

We have all been there.

It’s tough to make a decision when there are many competing factors involved.

But the good news is:

With the right information at hand, we can make better buying decisions.

This guide will help you understand the different types of Solar PV systems and what best suits you.

We start with understanding the basics of Load Analysis, AC and DC, working of the Solar PV system before moving on to classifying the Solar PV systems.

So, without further ado, let’s get started!

Basics Of AC And DC AC (Alternating Current)

This is the type of current where the flow of electrons reverses in direction many times a second in regular intervals. It is this type of current that is used by the grid and most of the load or appliances at home.

DC (Direct Current)

This is the type of current where electron flow is unidirectional. This is the kind of electricity produced by the solar panels and what gets stored in the battery.

The Solar Panel contains solar cells that convert the sunshine that falls on the panels to Direct Current (DC). An inverter is needed to convert Direct current (DC) generated by the solar panels / stored battery backup to usable AC Power.

Electrical Load Analysis

Electrical load refers to appliances which use Alternating current(AC) for their functioning. To perform an electrical load assessment, analyze the specific usage of each individual load to calculate the total load for the building.

Start by assessing loads that take up a lot of energy to gauge the major consumption of power. Also, initiate Energy efficient methods to reduce the power needed from Solar panels.

For more on electrical load analysis for different types of solar PV systems, please refer: Analyzing your Electric loads

Different Types Of Solar PV Systems

There are three basic types of Solar PV systems:

• Grid-Tied system
• Off-grid Solar system
• Hybrid Solar system

Grid-Tied Solar PV System

This system works only when there is grid power. In this system, the load is supplied power mainly from the Solar power.

Inverters convert DC power generated by solar panels to usable AC power. The DC to AC conversion happens as per the voltage and power quality requirements of the grid.

Power from the Solar PV either goes to the AC loads or to the grid via a bidirectional interface setup at the distribution panel.

The system requires no battery backup. If the load requires more power than the solar power generated, then grid power is used.

This setup enables the user to avail the Net Metering option to supply the extra power generated from the solar to the grid and avail credits from the DISCOMs(Distribution companies).

When there is power outage the inverter shuts itself and stops the production of electricity. This is a safety feature to help people who work on grid lines by stopping electricity flow from solar to the grid during power outages. (Also called Anti-islanding)

Off-Grid Solar PV

This system allows power to be fed to the load exclusively by the solar panels without any grid intervention. There is battery backup to store solar power to feed the load entirely from solar.

This kind of a system is ideally suited for remote places completely cut off from grid power. Surplus power generated from Solar is stored in the battery and utilized in case of low solar power generation (or non-availability of power from the solar.)

These systems are generally less efficient and more expensive compared to Grid connected systems.

Hybrid Solar PV

It is a combination of On-grid and Off-grid systems. It has a battery bank with an inverter which can work as On-grid or Off-grid system. Generated solar power can be used for supplying power to the load or for charging the battery bank.

There are 2 types of Hybrid Solar PV based on how the output of the Solar PV is connected to the electrical system(ie. DC or AC side)

DC Coupled Hybrid Solar

In this kind of a system, the solar output is connected to the DC side of PV system. The Direct Current generated by the Solar PV first flows to a charge controller which controls the current flow to the battery bank. The power then flows to AC loads via a battery based inverter.

Benefits of using this system:

• Only one inverter is used in the system which means simpler installation.
• This kind of a system minimizes energy loss with that happens due to inverter conversions from DC to AC or vice versa. Here the DC(Direct Current) getting stored directly in the battery bank.
• Also, the DC-coupled system is not limited by the inverter and able to route more energy to be stored in the battery without any DC/AC conversions needed.

AC Coupled Hybrid Solar

In this kind of a system, the solar output is connected to the AC side of the PV system.

The Direct current generated by the solar panels first passes through the batteryless inverter which converts DC to AC.

This is used by the AC loads through the AC load panel.

Any extra current could be supplied to the grid or stored in the battery after AC- DC conversion by the inverter.

Benefits of using this system:

• • Provides efficient power transmission over longer distances.
  • It inverts the DC from the battery to usable power in case of power outages, apart from providing charge control to batteries.

Which Solar System Suits You The Best?

If you are looking to save more money go for Grid tied inverters. It offers a number of benefits –

The costs are very less compared to Off-grid systems costs which include battery backup costs, maintenance, and other miscellaneous costs. Also, the utility grid acts as a virtual battery without any need for maintenance.

You can avail the option of Net metering – where you supply extra power generated from solar to the grid and you can avail the credit for it.

If you are looking to be energy sufficient then, the Off-grid option could be your choice. This works for places which are completely isolated and cannot access the grid power. For those who have access to the grid, don’t consider this option.

To get the dual advantage of On-grid and Off-Grid systems go for Hybrid Solar PV systems.

Takeaway Tips

Here are a few key takeaway tips for choosing the best Solar PV system.

1. Consider your energy requirements and go for the Solar system that best suits your requirements.
2. Compare the incentives available with the solar system ex: NetMetering option of going on grid v/s becoming energy independent with off-grid systems. Also look at the other different financial incentives available for the different options.(ex: Tax waivers, Rebates..)
3. Consider the make/ brand of the Solar PV system. Choose the one of the highest quality.
4. Consider your budget and choose a Solar PV system that fits your criteria.

The Author is a Solar Consultant and is passionate about Renewable Energy Technologies. https://www.lavancha.in