Yes, the calculation is based on $0.19/kWh charged by PG&E, with tiered rate, that cost does go up. So hosts will need to adjust the hourly prices depending on local cost and actual traffic. The $270 is from hosts with solar panels that have credits stored up. One user living in Santa Clara has 15000 kWhs saved up from almost a decade use of solar.

Thanks, that's a helpful example. This does sound like a great way for residential solar users to offload excess production, particularly if they can't tie it back to the grid directly (e.g., SDG&E's Net Energy Metering program [1]), or if the service rates can be higher than the grid-tie rates.

I guess that underscores that the napkin math gets pretty complicated and local use-cases can vary greatly. I'd be very interested in user-focused calculators that could help in guiding these napkin-math decisions the right hourly price to set locally, and/or whether the combo of residential-utility rates and local average public-charging prices makes it worth providing the service at all.

[1] https://www.sdge.com/residential/savings-center/solar-power-...

Yes, we have a ticket in the back-log to offer a feature that recommend pricing for the hosts. Taking into account public charging rates, utility rates, and traffic. The smart switch also has the purpose to distinguish charging vs just parking. So in some areas, we want to offer a separate rate for parking in the future.

Related: SDG&E offers a special 'Electric Vehicle' pricing plan with much lower rates ($0.09/kwh), but this special rate is only available midnight to 6am [1].

Most residential EV users will enjoy the reduced overnight rates, but probably not useful for public-service charging which usually takes place during the day when time-of-use electricity rates are at their highest.

[1] https://www.sdge.com/residential/pricing-plans/about-our-pri...

You know your stuff. A major problem the utilities face with EV charging is that there's only 1 meter per house. Utilities actually want to offer lower rates for EV charging, but with a single meter they can't tell what's being used for EV charging vs others. Currently it's the special rate over night. We have a smart switch prototype coming out in a week that can add internet to a switch and supposedly revenue grade metering. Of course, getting things approved by utilities could take months if not years.

PG&E's EV-B tariff is specifically for a dedicated EV meter, but the installation cost of a dedicated meter + box + charger is so much that it really doesn't make sense for residential applications.

eMotorWerks especially is experimenting with chargers that have wifi + a lot of smarts built into them.

Yes, I'm also trying to talk to residential charger OEMs on potential partnerships. I want to stay out of the hardware business if possible.