I don't know how much it adds, but the Tesla model S module has to have rigidity for the car and some puncture resistance etc. that might not be needed in a power application right? It also may need to have a much higher peak discharge and charging rate and cooling to accommodate that.

That's true. A vehicle-grade battery pack should also already come with the wiring built in so you can charge and discharge all the cells from a single point without having to make your own harness. Still, though, I'm not convinced buying a used Model S battery pack is a good deal unless you have an application that specifically needs it.

grid power where?

For PG&E in california, grid power is .23/.29/.51 per kwh (tiers depending on usage)

Here in Portland [1].

[1] https://www.portlandgeneral.com/residential/power-choices/ba...

You are forgetting delivery charges. It's between 0.11 and 0.12, with appropriate charges.

I would love to get that from PG&E in California. As it is, and with the high cost of energy in datacenters (because it's triply redundant, etc.) I've been researching natural gas power generation at home to power my render farm, instead of putting it in a datacenter.

I can do it for about $0.17/kWh, which is cheaper that the energy I get from PG&E. Fixed cost for the generator is about $7K to power the farm.

i'd factor in wear and tear on the generator there too they aren't meant for 24/7 use.

That's fair, but it doesn't really change the main point that you're looking at a stupid amount of hours equivalent to get to break-even while adding hundreds of charge cycles to an already-degraded battery. I can't really see this being a positive ROI purchase unless you want to use it for a vehicle. Used battery prices need to come down another 20-30% before it will make sense.

I'm surprised seeing that power-source chart for OR. In particular 60% NatGas+Coal, 30% hydro, 6% wind. Any idea why so little wind-power development yet?

It's not 3000 hours of usage, it's 3000 cycles.