Wait what? I'm with
@RobStark here and don't share your and
@Doggydogworld's concerns about solar lease renewal rates after 20 years.
Here's the facts:
- Average solar system installation size is almost 8 kW in California, current value ~$31k.
- Current historic cell degradation rates are about 0.7%/year, which over 20 years gives about 15% degradation.
- System will still have ~6.8 kW useful capacity after 20 years, 85% of the original. Typical warranties are 80% capacity.
- Technology improvements constantly reduced average household electricity use as well, relative to overall economic growth:
- Technological improvements do not just reduce the value of existing installations, they cut both ways: wet appliances, heating and cooling systems improve their energy efficiency. LEDs use much less power and smart homes will idle unused appliances better. (With the exception of EV charging, but see below.)
- Current per household electricity use is actually shrinking in the U.S. and in Europe.
So the outcome at 20 years renewals seems pretty clear to me:
- 6.7 kW system will still be perfectly good and cover much if not all the then current electricity use levels.
- Newly installed storage systems (Powerwalls, etc.) might further improve the effective generation capacity of old solar installations, without having to touch the roof.
- Many (I'd argue most) home owners would rather not mess with old roofs, which creates an additional disincentive to remove an existing, working solar installation.
- Even under your adversarial "old panels are obsolete" scenario a lot of the installation cost is going to be in installing the new panels on the roof and removing the old panels. If the new system is smaller then the roof that was shadowed by the panels for 20 years is going to have a different color, and will look ugly - re-roofing is much more expensive. If the new system has the same area then it either includes dummy panels which might look ugly or the supporting electric network will need rewiring due to higher capacity, etc.
- I.e. the cost of installing an equivalent 6.7 kW system using the latest solar cells will still be relatively high, and the renewal rates could price in that value of the system and installation cost and the convenience of not having to touch a working system. This is true even if new panel costs go down dramatically: installation costs, roofing costs and electric wiring costs wont go down, as they are mostly labor costs.
- So in reality, after 20 years Tesla will most likely be in a good position to offer the solar customer a renewal, and most customers who don't want to reroof will accept it.
The big risk to solar lease renewals after 20 years isn't people wanting all the hassle of removing older, perfectly working 6.7 kW installations just because there's newer ones available. The big risk is EV use exploding and people wanting to charge 4-5 family EVs, each 100 kWh or larger.
Can we also agree that this outcome will be a happy problem, that if EV use explodes fast then profits from Tesla's Storage, growing Solar and EV division will be more than adequate to cover higher than expected non-renewal rates of old solar installations, which could easily be upgraded by
Tesla after 20 years?