Quote:
Originally Posted by Vipergrün
Not to hijack this thread, but I'd be interested to know more.....website?
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For the Power Wall stuff, start here:
http://forums.pelicanparts.com/off-topic-discussions/920569-oooh-gotta-watch-those-tesla-updates.html#post9185780
The article is gone, but the wayback machine has a copy:
https://web.archive.org/web/20160701134946/http://investorintel.com/cleantech-intel/tesla-energys-incredible-shrinking-powerwall-warranty/
On our stuff, look here:
Outback Power Inc. - EnergyCell Nano-Carbon
The way to evaluate different batteries is calculate the total usable energy storage through the entire life of the battery. Divide the cost of the battery by this number. It will give you a $/kWh. Remember to take into account the battery degradation over the cycle life.
A Tesla battery is $3000. It stores 6.4 kWh of energy.
From the ORIGINAL warranty, it must maintain 85% capacity after 4MWh of cycling.
Using an average capacity of 92.5%, this is 5.92 kWh. 4000kWh/5.92kWh = 675 cycles.
It must maintain 72% after 9MWh, this is 1635 cycles.
And it must maintain 60% after 18 MWh, this is 3515 cycles.
$3000/18000= $0.167 per kWh.
BUT, the point of the article is TESLA has changed the terms of service and no longer honors those numbers.
A 2.4 kWh Nano-Carbon battery is around $250. Typical end of life for this type of battery is 20% loss of capacity. So, average 90% capacity. 3000 cycles @50% Depth of Discharge = 2.4*3000*.9*.5=3240kWh. or $0.077/kWh.