A couple of good reasons:
- The Model 3 expansion was very capital intensive, and when the ramp-up got delayed by 6 month future capex spending was a done deal.
- The Model 3 had to ramp up and start earning money, to pay for itself and to grow revenue.
- Tesla Energy on the other hand is a lot less capex intensive and thus was easier to mothball temporarily.
- Had they ramped up TE instead the Model 3 capex flow would still have happened.
- So they had to move the Model 3 to beyond the break-even point.
- They were also cell output limited, to about 20 GWh/year. The Model 3 is a +500% value-add to every 2170 cell made, so in the short run it was a much better platform to leverage revenue up.
- Tesla also has big, valuable, 100% profit margin software products (AutoPilot) with large, constant R&D overhead. The best platform to leverage this investment is Model 3 sales.
- Tesla Energy will have high growth, a lot of customers arrive over a car purchase. So the route to scale up PowerWall demand is via increasing automotive unit sales: I.e. the Model 3.
- Tesla being in part a "story" stock, a lot depended on scaling up the Model 3.
- About half a million reservations with half a billion in cash already paid - had the Model 3 not ramped up people would have requested the deposit back.
- Half a million reservations maps to at least 20 billion future revenue - this was a lot more certain than a TE scale up of demand.
Really, there was no other option but to make the Model 3 work.
Now that cell production expands dramatically by the end of the year I'd expect a lot more focus on Tesla Energy.