Hacker News new | ask | show | jobs
by dmitrygr 2552 days ago
you are forgetting that solar cells are not 100% efficient, and charging is not either. so you MUST use charge rates cites, not consumption rates
1 comments
nudded 2552 days ago
No, you must not. The energy required for the car to drive 12kms is 996 Wh. let's round to 1kWh.

Solar is DC. for instance Tesla powerwall is 97% efficiency for DC/DC conversion for charging its battery. So you need basically 1kW of solar to produce the needed energy to drive 12km (per hour). I think you are off by at least a factor of 3.

edit: at 20% solar efficiency that would require 5m^2.

link
dmitrygr 2552 days ago
so then your claim is they lose 66% on rectification of AC when they charge from a wall? :)
link
nudded 2552 days ago
No, my claim is that their solar claim is not ridiculous ;)

Also, if I do the math on their AC charging. 35km/h gained --> 2905Wh energy. Standard 230AC, 16 amps is 3680W. So I guess the number there is also correct? Take about 85% efficiency, then you have 3000Wh in one hour from 230V AC

link