Economics of the Tesla Powerwall in India

Elon Musk, the serial entrepreneur and CEO of Tesla Motors recently unveiled the much anticipated battery, the Tesla Powerwall, that they had been working on. The specs and the design look awesome. To convey the message in an image, here's the deal!

So I have tried to work out an economic calculation of whether it would be a good bargain to invest in this battery or solar energy. First let us calculate the cost of electricity of a household in Delhi. A typical household consumes about 20 units(kWh) of energy daily, which according to the current rates of BSES would cost about Rs. 4000 per month, or 48,000 per annum. For Mumbai, the rates are even higher.

Now coming to having solar power in your place, the two main components are solar panels and the battery. To have a 20 kWh system, it is sufficient to have a 2 kW solar panel and a 10 kWh battery pack. The requirement for the day would be met directly as the sun shines and the battery would do its job in the night. At present rates this could cost you around Rs 1-1.4 million. But with the introduction of the new Tesla Powerwall this would reduce drastically.

The cost for a good Indian 2 kW solar panel at Rs. 30-35 per Watt would come out around Rs 60,000. The cost of the battery with the additional charges of shipping, insurance, duties and taxes works out to Rs. 460,000 (at exchange rate of Rs. 63.73 per USD). With a 10 year warranty for the battery and a 20 year warranty on the solar panels, the cost of maintenance is not an issue. So the total cost turns out to be Rs. 520,000 for a period of 10 years, or Rs. 52,000 per year.

But if you are consuming more than 600 units a month, this is the deal for you. The power connection would be integrated with your mains supply and you could switch between the solar power or the mains power. Thus all the savings would incur from the costlier tariff slabs.  I have shown the savings for the various categories of consumers in the following table:

Monthly Consumption(kWh)	Electricity Bill(Rs. per year)	Savings (Rs. per year)
200	12,000
400	27,600
600	48,000	-4,000
800	67,200	3,000
1000	89,000	9,400

So even if you are a person not very concerned about climate change, but you are just a sadistic remorseless rationalist miser, it would  make perfect sense for you to go for a Tesla Powerwall.

And for those of you who like this idea, please spread the word.

I have made use of the following assumptions:

1. Neglected the government subsidy on solar panels, as most people would like to avoid the hassles of dealing with the government
2. Assumed no increase in electricity tariffs, and zero cost of money (basically zero interest rate). I feel both these issues will more or less compensate each other.
3. Assumed 10 year life, while the expected lifespan of the system would definitely be higher

If anyone is interested they can do the math taking into consideration the above factors.