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I have a cunning plan!! Instead of buying 8 power walls at a...

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Aedo

361 Posts.

04/09/23

16:41

Post #: 69724665
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Originally posted by GiddyYup: ↑

There are many people who seem to believe the narrative that they can or will be able to charge their EV from a home battery system which is surprising given the basic numbers:

A Tesla Model S car has a 95kWh battery

A Tesla Powerwall 2 has a 13.5kWh (usable) battery capacity

A Powerwall 2 costs approx $15k per unit installed, excluding solar panels and related equipment necessary to charge the battery.

To fully charged a Tesla S car you would need 8 Powerwalls at a cost of $120,000 plus a massive array of solar panels etc.

The Powerwall 2 is approx 90% efficient so you need at least enough panels to reliably produce 105kWh for the batteries.

The batteries have an estimated lifetime of 10 years so you will need to factor in a cost of approx $12,000 per annum in replacement costs ignoring inflation. Probably about the same for the car also, plus the solar panels and inverters etc. All up its easy to see that an EV charged from home batteries would end up costing more than $30k per annum.

I don't say that its not possible but I do ask who in their right mind would do it if they knew the economics of storing that amount of power. Thats why almost every EV user charges and will continue to charge from the grid. That also why demand for grid power is rising rapidly and one of the key drivers of massively increased retail power prices.

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I have a cunning plan!! Instead of buying 8 power walls at a cost of $120k buy a used Model S for under $50k and get an 85kWh battery!!
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