Guide Why you should install a solar rooftop system

Mohan997

Contributor
Hi! This post aims to show people how beneficial getting solar rooftops in your home would be. This will show how much money an average household could save by switching to a solar rooftop. Let’s analyze the savings using my consumption as an example.
I live in Chennai and consume around 1100 kWh per bimonthly cycle. Below is the TNPDCL tariff structure for reference:

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With 1100 units consumed, my bill totals ₹8,025 per cycle.
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I'll be getting a 3 kW plant based on my consumption. On average, a 1 kW plant would generate 4-5 kWh /day. You can either generate 3/4th of the requirement and pay the difference. Or you can have a surplus of units, which will be carried over to the next billing cycle. Very few states allow an annual cash payout for net excess credits. Most carry over to next year.

Now, let's break down the cost of setting up a 3 kW plant.

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With the govt. subsidy, PM Surya Ghar scheme, I'll be getting ₹78,000 back, bringing the net investment amount to ₹1,32,000.
Now let’s compute the new bill. The 3kW will generate at least 4 x 3 = 12 kWh /day, or 720 units /bimonthly cycle. So now, I'll only pay for 400 units instead of 1100.
Screenshot 2025-02-24 at 6.36.42 AM.png


With an annual savings of ~₹40k, the system will pay for itself in approximately 3 years, after which all savings become pure profit. Since solar panels have a lifespan of ~25 years, this translates to decades of reduced electricity costs. During peak summer, the system can generate up to 16 kWh/day, naturally balancing out higher seasonal electricity consumption.

In conclusion, a solar rooftop system is a one-time investment that significantly cuts electricity costs, offers government subsidies, and pays for itself within 3 years, leading to huge long-term savings.
 
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@Mohan997 ,
Thanks for the details.

Do post further details regarding the following.
1) Is this setup for an individual house/Duplex? How high is your setup and which directions are the setup facing? How much area is covered?
2) Do post the break up of cost of setup like panel name and type, Inverter, etc.,
3) What is the procedure for applying for a net-metering setup.
4) Are you setting up using PM Surya Ghar based contractors or individual contractors. If so their quote please?
 
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@?dOuBtFiRe? I haven't set a grid up yet. My uncle, who lives in Pondy, set it up for his house. I'm planning to do it soon, once I have the funds.
You can lay the panels at surface level on the terrace or build steel structures and raise them high enough to free up the terrace. My uncle's setup is 5 kW and takes up around 600 sqft.
It's better to use monocrystalline panels; even though they cost more, they'll take up less space and are more efficient.
If you want govt. subsidy, you must go with vendors registered through the PM Surya Ghar scheme. You can check the list of vendors here. They'll also guide you with applying for the net-meter.

@VasagadekarPratik You can go off-grid and store it in batteries, but it's too costly. I'd recommend net-metering. If you live in a remote area, then yeah, I guess. Otherwise, it's much better to connect it to your discom.
 
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Off-grid solar has been a dream of mine for many years now, I'm hopeful I'll be able to do it in the next few years.

Pretty cool that 700+ watt panels are finally available to us. A rough calculation shows 24 panels with >50kwh in LFP batteries would bring my bill down to 0.

Most off grid enthusiasts say you need to size your system for at least 72 hours of operation, but that's not necessary when you do have grid as a failback during cloudy or monsoon days.
 
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off grid though sounds great it becomes too costly and for most it isn't really worth it. You will have to spend a lot on batteries and it also needs periodic replacement. The solar panels will have 25 years of life but the batteries don't, so replacement of batteries every few years add a lot to the cost. Plus you need a separate place to store the batteries safely, plus fire hazard, plus regular maintenance, plus fumes. Then after all this you will anyway need the grid electricity because a 3kw solar won't be able to power your whole house if your consumption is 1100kwh per month.

If you all it all, off grid isn't really worth for most.
how much will a 5kW off grid solar system cost ? what is net metering ?
 
Off grid vs on grid depends on which state you live and what are the terms and conditions of On-Grid.

In states like mine Karnataka, for On grid you only get to export power as per your sanctioned load. To increase the sanctioned load itself requires greasing palms and other expenses. Not to mention the higher fixed tariff. All of this alone is enough to buy one or 2 lead acid solar batteries.

In cases where the tranformer for a new construction, they will ask you to spend money on the pole, road digging and other expenses. This can cost as much as a 4 solar batteries and a off grid inverter.

Then there is the fact that On grid prices of solar costs 50 to 100% higher in capital. Since you can only buy and install from vendors/manufactures approved from MNRE.

So for people who do DIY (except for panel structure mounting/fabricating and lifting/panel mounting which require hard labor or manpower to lift heavy panels and metal structure.) , the cost of off grid without subsidy will be the same as On grid with subsidy.

If you have a roof with no shadows you can just place them on the terrace with minimum effort with just another pair of hands. With a small structure/stand.

If you already have a sheet metal roof on top of your terrace, again with just a extra pair of hands you can mount them yourself .
 
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