I want smart appliances, not the current commonly understood “smart” Internet-of-Things (IoT) appliances, but smart in actually useful ways. A couple years ago I had solar panels installed. The “smart” I want is pretty simple: I want devices that know about surplus energy. Devices which have lower power idle modes that can kick into more productive usage when solar power is bountiful. Generally IoT devices seem to be almost everything I don’t want. I don’t need devices that listen in on my conversations, track my data, and open up security holes in my home network. In this post I want to outline what I do want from “smart” appliances in my home.

In California electricity metering for residential solar customers typically involves variable rates for off-peak, partial-peak, and peak usage. In essence, when everybody is awake in the middle of the day (peak) grid-power is the highest price while 3am when little utilization is present (off-peak) the price is lowest. Solar customers typically contribute back to the grid during that peak demand and then generate nothing after dark and will draw from the grid in partial-peak and off-peak modes.

What this means in practice is that there is incentive to run electricity intense workloads either in mid-afternoon, when I am generating “free” power, or in the middle of the night when grid-power is cheapest.

Accordingly some behaviors have changed. We don’t place a load of clothes in the washer whenever but rather will use delayed starts to fall into one of those optimal time periods. The same goes for the dishwasher. When I had an electric car, returned during the pandemic, it was programmed to only charge in the off-peak hours as dictated by the utility.

Side note: if you have a home-charger for your electric car, it still might be too expensive to charge off of solar during peak. Our Nissan Leaf would draw 6.6kW while our slightly oversized solar system maxes out at 4.6kW. It was still more cost-effective to charge at night.

Programming timers is a simple and effective way to spread out electric load, but I want smart devices, not timed devices. Other major usage falls into:

  • Climate control (AC/heat)
  • Refrigerator
  • Computer(s)

Each of these could be smarter in their electricity usage. Products may exist for these use-cases, but most of what I have seen are for off-grid applications rather than “smarter” residential on-grid energy consumption.

Climate Control

I would love to be able to set ranges of acceptable use for surplus energy, especially when it is hot. For example, in the hottest periods of the summer to reduce load on the grid and comfort in the house, nothing should try to push lower than 74F, but we’re generally comfortable up to 78-80F inside. This is of course zone dependent, some parts of the house we do not typically occupy during the day, so those can be safely allowed to get warmer if there is no surplus power available. If surplus power is available however, they should stay at the desired comfort level.

Even smarter would be to recognize that surplus power falls off at the end of the day, and to be proactive and pre-cool or pre-heat areas of the house before the surplus power disappears into the sunset.

Refrigerator

The refrigerator is the biggest constant energy draw we have in the entire house. The ideal smart refrigerator would turn surplus power into reserve “cold” for use as that power dissipates, basically with the objective of reducing the amount of times the compressor needs to turn on during non-surplus energy periods. Ideally it would tap into these same surplus power events as other appliances and freeze a coolant bladder or something analogous. If there were some way to only run the refrigerator off of solar power, allowing it to turn itself into a glorified icebox through the night, that would be incredible.

I definitely don’t want an “off-grid” refrigerator, but somewhere in between what off-grid folks do and the typical residential unit would probably fit my desired use-case.

Computers

Unsurprisingly, I run a number of computers at home, having a gigabit fiber line has certainly helped me “domesticate” some of my prior remote server workloads. The “smartness” I would like is to queue up or schedule high CPU tasks for either surplus energy periods or off-peak periods. For example, video encoding, encrypting backups, or image processing could all be spun up during these periods of cheap energy.

What could be even more interesting is that if the computers pinned their different CPU performance profiles to these events. If a chipset supports three frequency, and therefore power utilization levels, during peak/partial-peak periods with no surplus energy available if they pinned themselves to the lowest setting, and letting the OS scheduler sort it out after that, would be quite interesting.

For laptops that are mains connected, it would also be interesting to have the computer self-regulate off of battery power to both keep the battery from deteriorating on constant mains power, but also to spread electric load around during the day.

Overall I think the challenge for homeowners like myself is around capturing surplus energy to make use of it. As is widely reported, the biggest challenge with solar applications is that surplus energy capture during the day. From an IoT or “smart” device standpoint, the biggest challenge to me is security and privacy. I am extremely weary of internet connected devices that area reporting data about my life back to an unknown number of data brokers. Or worse, devices which open up security holes on my network and endanger me in other ways. I’m happy to put devices on the wireless network, I’m much less happy when they talk to “cloud services.”

The peak “give back” to the grid I have observed on my system has been over 3.5kW, which is great for my net usage report but I end up “selling” highly valuable energy at a low rate, and then buying back electricity when I need it.

The more I can reduce the amount of energy I have to “buy back” from the power utility the better!

If you have tips for smart appliances or other solar utilization tips, feel free to shoot me an email to rtyler@ this domain :)