So last time, I rambled about some aspects to home power. Today, I’m going through my thought process on the next phase.

After much thinking and evaluation, I decided to do the free electricity period because the math works out very favorably if the provider is willing to zero out transmission charges during the free period. In this case, I chose Reliant Overnight 12. I did some unexplained and crude math in the Excel file where basically, if I’m about 60% nighttime usage (defined as between 2100 and 0500 local time), I will come out ahead. Obviously the biggest challenge here is that looking at historical consumption is a really bad way of looking at the problem when you have solar + battery because your usage pattern can change based on your incentive.

Think about a standard fixed rate plan - you use electricity whenever you want to and the only incentive is simply to use less to get a lower bill (unless you have one of the plans that commits you to a certain amount of usage per month). With solar and you are on a simple buyback plan (where the grid buys your exported), your incentive is to minimize consumption and maximize export. But with TOU (time of use) especially ones that have super-free periods of use, your incentive is different: minimize consumption in all times of the day that are not the special TOU, and in the TOU period, move as much usage to that as possible.

So, how am I going to swing as much of my consumption to the night as possible:

  1. Consume as much solar power as possible. When the sun is out, I am going to use the A/C as much as possible. Lower the setpoint until some arbitrary criteria are met e.g. production goes down or battery level drops below some amount.
  2. However, I want to conserve as much power as possible before 2100 while power production starts to dip due to solar dropping off.
  3. Optimally, consider the amount of electricity produced before allowing a car to charge, but my Wallbox Pulsar does not seem to stay connected to wifi to save my life, so I’ve put it on a schedule forbidding charging in the afternoon.
  4. During the free TOU, charge the batteries and cool the house to as low as the humans in the residence are willing to take it (turns out, the wife and kids may not want to be popsicles in the morning) as well as charge whichever EV is plugged in before sleepy time.

The real problem is very human: how do you advise your family how to best use electricity in this scheme. “Don’t use electricity except when we have excess or the sun is out but not when it’s in the afternoon and especially if there’s a storm predicted to be coming in etc. etc.”? I’m sure my wife is eager to think carefully about “Can I run the laundry given these constraints?” when two small children are hounding her or fighting each other for the 100th time that day.

Indeed, we charge the Chrysler Pacifica Hybrid at any point in the day because it’s only got a 12 kWh battery, but then what about the dryer? What about the dishwasher? What about XYZ?

My thought is to see what the basic automation can do and reevaluate after a few months. Now, on the mechanics of how I’m going to implement if/else with Home Assistant at the helm, I’ve decided to use AppDaemon, and this is the repo I’m storing the app in. While I think the Home Assistant automations could do it, I just felt I wasn’t able to expressive enough to pull it off.