When something is supposed to be at your home for 25 years, it’s a big thing. And when that something happens to be a solar system, the decision becomes even more crucial. That’s because the electricity from the system will power your house.
One of the most challenging things as a beginner is to choose between the different types of solar systems for a home. The major types include an on grid solar system, an off grid system, and a hybrid system.
The on grid solar system is the most beneficial option for most cities with a reliable grid. We will spill all the beans about what this system is, how you should calculate its size for your house, and even the installation cost.
Dive in for details!
On-grid solar system: A basic introduction
Before helping you learn how to find the suitable capacity of the solar system, we find it pivotal to explain what an on grid solar system is. So, here we go.
An on grid system is also called a grid-tied solar system. The name in itself indicates that this system is connected to the electricity grid. Here’s how it works.
- Solar panels on the rooftop convert sunlight into the DC form of electricity
- DC power is supplied to the solar inverter and converted into AC electricity
- The units that aren’t being consumed in real-time are exported to the grid
- At night, electricity units are imported from the grid
- This export and import of electricity is facilitated through net metering
- A bidirectional meter is, thus, an imminent part of an on grid solar system
- This meter records the unit exchange
At the time of bill generation, the reading from the bidirectional meter is used.
How to select the size of the solar system?
This is one of the fascinating things to decode as a beginner interested in going solar. Solar systems come in multiple capacities. But buying the right size makes all the difference.
If you buy a system that will produce much less power than you consume, your electricity bill will not drop by much. And if you buy a system that will produce much more energy than you consume, it will be a monetary disadvantage (we will explain the ‘how’ a little later in this guide).
Hence, you need to determine the correct size of the system, and it depends on the number of average electricity units you require.
You can use your electricity bill as a reference. Suppose your average monthly unit consumption is 360 units.
Here’s how you can calculate the right size of an on grid solar system for your house.
A 1 KW solar system produces roughly four units of electricity daily. Which means it will produce approximately 120 units of electricity a month.
So, if your average monthly electricity consumption is 360 units, you will require a 3 KW solar system. How?
Divide the units you use a month by the number of units a 1 KW system produces in a month, i.e. 360/120 = 3 KW.
Here’s a reference table that’ll help you further.
Solar system size | Units produced per day | Units produced per month | Units produced per year |
1 KW | 4 | 120 | 1,440 |
2 KW | 8 | 240 | 2,880 |
3 KW | 12 | 360 | 4,320 |
4 KW | 16 | 480 | 5.760 |
5 KW | 20 | 600 | 7,200 |
6 KW | 24 | 720 | 8,640 |
7 kW | 28 | 840 | 10,080 |
8 KW | 32 | 960 | 11,520 |
9 KW | 36 | 1,080 | 12,960 |
10 KW | 40 | 1,200 | 14,400 |
Why should you choose the system size wisely?
It’s simple to understand why you shouldn’t install a system that produces less power than you require. But, there’s a misconception that if you buy a system that produces more power than you can consume, you can earn money by selling the extra electricity to the electricity board.
However, there are a few things that need explaining here.
- The extra units supplied to the discom get lapsed at the end of the year
- Units generated from solar are sold at petty rates, i.e. if your discom does buy those units
When you compare the returns with the amount you invested, you’ll realize that picking the right size is the better deal.
To explain it even better, let’s walk you through the cost of installation of an on grid solar system.
- 1kw – ₹60,000 to ₹80,000
- 2kw – ₹1,10,000 to ₹1,50,000
- 3kw – ₹1,65,000 to ₹2,10,000
- 4kw – ₹1,80,000 to ₹2,80,000
- 5kw – ₹2,25,000 to ₹3,50,000
- 10kw – ₹4,20,000 to ₹7,00,000
Using these figures, we will now quickly explain how investing in a system that produces way more power than you can consume is a wrong decision.
Suppose your electricity consumption is 360 units, and the tariff you pay per unit is ₹10. So, without a solar system, your monthly bill will be approx ₹3600. After installing a 3 KW solar system, it will be almost nil.
Now, a 3 KW system will cost between ₹1,65,000 to ₹2,10,000, and your yearly savings after going solar will be approx ₹44,000. It means the initial investment cost will break even in 4 to 5 years (in fact, a lot sooner if you’re eligible to apply for a subsidy).
Imagine that instead of a 3 KW system, you purchase a 5 KW system. You will have to invest ₹2,25,000 to ₹3,50,000 for the installation, and the extra 240 units (600 minus 360) will either lapse after getting adjusted in your bill month after month or the discom will buy them at nominal rates.
This will be a poor investment because, in this case, it will take about 6 to 8 years for the cost to break even.
And that is why you should only invest in an on grid solar system of suitable capacity.
Conclusion:
Installing an on grid solar system of the right capacity is quintessential to maximize your gains from going solar. And we hope that by now you’re solid with numbers and have a decent idea about your requirements.