A similar situation exists in Europe. The grid and energy supplier are different companies, but in this case it's the grid which charges you more for peak usage.
So a 100 or 200kW grid connection is a lot cheaper then a 500kW connection.
So to get this back to the Ecotricity vs Tesla discussion: We'll see this more often as we get more locations. Local buffering of energy will be required I think to be able to support Quick Chargers.
To add a litte information:
1. Most major new SCs in Norway (6 or 8 bays) had to get a new transformer in order to provide enough power.
2. There is 1 charger for each 2 bays.
3. 1 charger (the newer ones) are at 135KW.
4. For a 8 bay SC location this means 4*135KW power need. Or 540KW or 0.54MW.
5. As your population of cars grow you will see full utilization of all bays. We are already at these levels here in Norway with queuing happening frequently at some SCs.
6. A battery pack in the SC setup would need to be seriously large in order to have any useful effect when the SC is experiencing constant use on all bays.
7. Tesla has paid for the upgrade of the local infrastructure. (According to newspaper articles in the local paper for the area where the new SCs have been built).
8. Tesla has usually also added in spare capacity both in the infrastructure and the parking lot to allow for future installation of a pair of 22KW type2 outlets or a ChaDeMo or Combo stall.
9. Local landlord or similar is believed to have demanded that only some (2 or 4) of (4,6 or 8) bays be reserved for Tesla. The others usually marked with P - max 30 or 45 minutes. Consensus in other forums that as landlord sees actual use of more than the reserved bays they will change the signs for more to be reserved for Teslas. This is the situation at many SCs in Denmark, Germany and Netherlands - and lately at some Norwegian SCs too. Usually the landlord also owns/operates the local shop/café and wants to ensure maximum use of the parking area.
So - back to UK/Ecotricity/Tesla issue:
Tesla must be ready to pay for infrastructure upgrade. If a site has too little available power due to insufficient cabling over a significant distance I understand that the cost of upgrading will be high - then find another site. If not - then reason with Ecotricity or the landlord.
My family did a road trip in our Tesla from Norway, via Denmark, Netherlands, Belgium and France to UK this summer. Return via same countries + Sweden. We used SCs where possible. In the UK we arrived via the chunnel, used the SC in London, then drove to York, Chester and back to London. En route in UK we used Ecotricity and ChargeYourCar chargers (22kw). They all worked fine as long as we were able to get them opened. As this trip was on a whim we did not have any "membership" cards for any of the 22 UK charging networks. We did however always get very good help from Ecotricity and ChargeYourCar who remotely opened chargers for us (or directed us to another charger that did have the remote option). I do look forward to the day when all of these charging networks have consolidated (merged or othervise) or have made alliances or roaming agreements. I do not plan to drive around Europe with a big stack of cards in order to charge when we go "off the highways" and get too far away from the SCs.
8.
near the Blackwall tunnel.
