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Integrating PW2 with a smarter house/car charging

Integrating PW2 with a smarter house/car charging

I have posted in the general forum but now PW II users have their own I will post here.
I have a small PWII setup and 10kWp solar. My wife runs a Chevy Volt and I drive a Golf GTE (both PHEV). I have a deposit on an M3 but since I live in the UK we've not been told whether it will arrive in this decade (if it ever will).
My goal is to minimise my energy bills.

The first info I wanted was to view my generation, battery state and demand over a reasonable period of time - so the rather limited Tesla app wasn't any help.
Luckily there is some JSON data available on the PWII gateway and with a few lines of Powershell I have created https://www.bowmill.net/xmenu/powersoc.shtml
Fronius also expose similar data so there are corresponding pages for the inverters. The jury is out on the best way to monitor use. I started using plug adapters from a company called CurrentCost but I think they disappeared so I am trying Vera (z-wave) but finding their boxes very unreliable.

I have been controlling the charge rate on the Volt via the ODB port but this method seems to have caused quite a few premature failures of the attached charger (3 so far).

Zappi http://myenergi.uk/product/zappi/ looks promising but, as yet, they have no published API

The reason for this post is to see if anyone else is having any success playing in this area/has any pointers to interesting hardware/has any examples of similar work.

Steve

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Atom12 | 20. März 2020

Flagged kouipleirpl. But, since I'm here will add to this 3 year old thread. If Elon adds "charge current" to the Model 3 remote API suite this problem is easily solvable. As of yet, one can only accept the in car setting.

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contact | 01. Juni 2020

I have a Zappi EV Charger that is designed to monitor excess solar and charge your EV from solar (you can adjust the solar/grid percentage to whatever you want) - https://myenergi.com/product/zappi/

But in addition to its standard features I wanted something that wasn't on offer, so I have 'hacked' my Zappi EV charger so it 'Boost Charges' when the variable tariff I am on drops below the rate I get paid for exporting my excess solar (the rates can change every 30 minutes) - https://youtu.be/vhnQqKtkb00

The only problem is that when the system activates it takes energy from my Powerwall (that I have filled with solar from my roof), rather than from the grid, where (at that time) it costs less to buy than the rate I get paid for exporting excess solar to the grid.

I can prevent this by manually switching my Powerwall to 'Back-Up Only' using the app, but I would really like to be able to do this automatically when the rate I am paying per kWh drops below my fixed export rate, as the lower prices often occur early in the morning, while I'm asleep.

If this could be done, there is a small added bonus in that if the Powerwall isn't fully charged when it switches over to 'Back-Up Only' it will charge to 100% at the cheaper rate.

Does anyone know how to automate switching over the 'Back-Up Only'? Can it be tied to a variable tariff threshold?

Being able to export from the Powerwall during peak demand periods would be nice, but in the summer I'm still creating excess solar through the peak periods and my house needs about half of my Powerwalls capacity to run till sun up the next day. In the winter I'm going to need everything that is in the Powerwall to run the house plus some from the grid, so no spare capacity then to sell then. Plus I'm currently on a fixed rate export tariff.

Maybe an electro-mechanical solution like my Zappi Charger 'hack' could be wired into the gateway to locally do the switching and bypass the app/web based control?

TeslaTap.com | 01. Juni 2020

I like your plan with the Zappi but I can't with that project. If you charge an EV, you might consider a different strategy in part, where you charge the car during the day when you have strong solar. I wrote up more details about this, how it can save about 10% for the amount your Tesla is charged: https://teslatap.com/articles/solar-powerwall-system-optimizations/

kaushal88027 | 04. Juni 2020

I can prevent this by manually switching my Powerwall to https://bollyshare.info/ 'Back-Up Only' using the app, but I would really like to be able to do this automatically when the rate I am paying per kWh drops below my fixed export rate, as the lower prices often occur early in the morning, while I'm asleep.

TeslaTap.com | 04. Juni 2020

@kaushal88027 is a copy and paste bot - please flag.

gregbrew | 04. Juni 2020

I would if I could, but I have no mechanism to flag posts, and Tesla won't acknowledge my multiple requests to verify my account. It's very frustrating to find that over half of new posts are spam bots, and I can't even report them to clean up this forum.

I only stay here to help others, as I've got over two decades of residential solar and EV experience, but I'm getting ready to pack it in.

TeslaTap.com | 05. Juni 2020

@gregbrew - I appreciate you staying around! With COVID, it seems many of the key Tesla forum employees are out of the picture right now. It may also be that "owners" are only those with Tesla cars, which doesn't seem fair for those with Tesla energy. I'd try again to get owner status in a month or two when things might get back to normal.

gregbrew | 05. Juni 2020

I appreciate it. It's good to hear kudos from an actual human, rather that a copy-paste spam-bot, with copious "thank-yous" and unrelated links to Indian brothels thrown in.