I'm at the end of a fairly typical summers weekend in Australia. Not too hot, lots of sun and everything in my house was powered by the solar panels on my roof. Here is my home dashboard right now:
Even though the sun is on the way out my solar is still outputting 1.2kW, it's a tad humid so the aircon is on low and the house is drawing 1.2kW - so net neutral right now. Below that you can see the house (Powerwall 2) and car (Model S) batteries are fully charged (I only charge my car to 90% unless I'm about to go on a very long drive).
In the Smart Meter box you can see the full stats for the entire weekend. Yesterday I consumed $0.04 of power and today I used $0.03 of power. This is caused by spikes in consumption such as the fridge or air conditioner compressors starting up - it takes a split second for the Powerwall to ramp up and for that tiny bit of time the grid provides a little power. This goes away if you disconnect from the grid entirely and is just an artefact of how the Tesla Energy Gateway watches your usage and tries to match it when it's in an on-grid environment.
Finally the column on the right in the Smart Meter box is how much excess power I sold back to the grid, $2.66 yesterday and $0.95 today (I charged the car up today which is why I exported less).
Today I saw an announcement that in South Australia the state government is going to fund 50,000 homes getting a similar system as me (solar+battery) and combine them to create a virtual powerstation! Such an awesome idea, I can only hope more states in Australia follow suit. If all homes had solar and batteries we could easily cover all residential power consumption in Australia.
Amazing stats.
You reckon Power Ledger will do great in Australia?
Power Ledger I think is a great idea to enable p2p trading of energy but I do wonder if what South Australia is doing (joining up 50,000 homes into a big virtual power station) might make it a bit redundant? Power Ledger has a much lower barrier to entry though and would certainly work in a scenario where joining into a virtual power station isn't an option.
Cheers, you know so much about this area
This is awesome. I’m so impressed that you’ve gone solar with an electric car. That must be saving you a huge amount of money. Have you calculated a payback period for everything?
Primarily I chose them for environmental reasons rather than financial. Solar panels are definitely now at a price point that they make easy financial sense (most systems pay for themselves inside 4 years). The Powerwall is probably nearer to a 10 year break even point at the moment but it also gives you some nice features such as power independence (i.e. it can power your home even if the grid is unavailable) so depending on what value you put on that feature they can make financial sense. The Tesla car however does not make financial sense at all 😆 That was a purely emotional purchase and I really should have avoided taking one out for a test drive. I had intended on only getting a Model 3 but Elon Musk knows how to sell: As you put in a pre-order for a Model 3 we would love to offer you a test drive of a Model S, which of the following days are you available? ... genius 😁
That’s funny. But if you’re in a position to own a Tesla then why the hell not? :)
A really interesting read Scott! I’m looking at buying property/a house at the moment and one of the keys features that excites me is getting it totally off the grid (electrical and water). I’m excited to see where the technology can take us in the future.
Any particular reason you usually charge your car to 90% and not 100% ?
Tesla recommend only charging to 100% when you need the extra range otherwise it just puts undue strain on the batteries (and could lead to reducing the overall lifetime of the batteries). Also when the batteries are at or near 100% the car can't do regenerative braking and it makes the driving experience very different, you get used to one pedal driving and when it's not there it feels weird :)
I always thought a full charge and full discharge cycle is best practice for battery...ofcourse Tesla knows what works best for their tech.