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Comment by dbjacobs | Hacker News Reader

If you are generating 5kw and using 4kw only 1kw gets sent to the grid. So you are not selling those 4kw at wholesale prices and buying it back at retail. Only the power that is time shifted gets this treatment.

You are free to buy batteries to do your own shifting. Also remember that wholesale costs typically just account for power generation, while retail costs also account for grid maintenance. An owner with solar is benefiting from grid maintenance, so it makes sense that they contribute.

Now from a societal perspective you may want to subsidize solar. But it certainly isn't "unfair" to buy power at wholesale and sell it at retail.

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Unfortunately this is not the case! TVA has a "sell all buy all" rule, that if you are connected to the grid and generate 5kw, you are required to sell all of those 5kw to the grid (at wholesale price). Then you buy back the 4kw you use (at retail price). It doesn't matter if you were only using your own generated power, you still pay. Crazy! I didn't believe it the first time I read it either, but that is really the law they adopted.

Even crazier. In France, the setup is similar: you sell all your energy to EDF, and they sell it back to you. I don't know if that's still the case, but a few years ago, the KWh you pay to them was cheaper than the KWh you sell.

If the selling and the buying happens at different times, then that doesn't seem so crazy. The real cost of electricity is dependent on supply and demand - which varies with time.

In certain parts of USA demand is especially high when the sun is at it's peak and most places on earth see low demand in the middle of the night.

All the rule does is prohibit net metering. If you never sell your power on the grid it's irrelevant. So you're free to use your 4kw directly.

Presumably this is a hassle because most equipment is designed for net metering where the system is setup to feed all generated capacity to the grid and consume all energy directly from the grid. So without net-metered billing, to avoid paying the retail premium you'd probably need a very expensive system that eliminates the cost effectiveness.

In fairness, AFAIU most utilities despise net metering. From their perspective they're the ones getting screwed, and the TVA billing system more fairly compensates them for infrastructure costs.

According to the link sent by eppp TVA doesn’t allow net metering.

Edit: I got the terminology wrong. I agree that expecting net metering (“free” time-shifting) is not reasonable. And it seems that in addition to the “sell all, buy all” solution it is also possible to sell (or buy) only what remains after (or is required for) local consumption. https://www.tva.gov/Energy/Valley-Renewable-Energy/Dispersed...

Net metering is not the same thing as only paying for what you use. Net metering means you could push 4 kWh during the day and draw 4 kWh overnight and get metered as zero consumption from the grid. This pushes a storage and distribution cost onto the utility and its other customers. Paying you at wholesale for the daytime push and charing you at retail for the nighttime draw moves those costs back to you.

What others are saying above is that you could generate 4 kWh during the day and consume it on premises, i.e. with air-conditioning or other day time appliance use, and still have zero consumption from the grid. This is also the point of the powerwall and any other on-premises energy storage.

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