Comment by SamBam | Hacker News Reader

Comment by SamBam | Hacker News Reader

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It's confusing on this sparse page, but no, you do pay for what you generate. It's a version of a rent-your-roof system.

If you choose to "subscribe," you are committing to paying Tesla 10-13¢ for every kWh you generate. You are then (if you're in a state with net metering) selling it to the state for a profit.

In CA, the average cost of electricity is apparently about 16¢/kWh. So you're making a profit of 3-6¢/kWh.

The incentive to you is that it's free to install, and has no commitment apart from a fee of $1500 if you want to remove the system. The incentive to Tesla is that they are selling electricity to the state for full price, minus 3-6¢/kWh to you for renting your roof.

I was trying to run a similar arbitrage operation when the Tesla powerwall was first released but the breakeven was ridiculously long. Mine was to charge the powerwall when electricity was cheap on the grid and sell during peak. I found that a lot of the grids don't really support this kind of arbitrage at all and with the ones that do, the profit margin is so thin that it's basically not worth it.

As you say, Tesla is reframing the argument from renting your roof --> you selling clean electricity to the grid to make it more palatable but I don't see a problem with that.

Are you buying into a network to buy power all the time at that rate? Or is it still when your specific solar installation is making power that you may buy it at that rate?

You're buying power from the utility company, at whatever rate they set, and at the same time you are selling your power to them, at whatever rate they set. They can be thought of as two separate transactions.

(You buying power can be thought of as a sunk cost, as this isn't changing it at all (unless you are also storing power), so it can be removed from the question.)

At the same time that you are selling power to the utility company, you are also paying Tesla 10-13¢ for every kWh you generate.

If you are able to sell at a higher rate than that, you keep the extra.

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