Thread by @ChazTeplin

A thread on my home’s heat pump performance during the recent Colorado cold spell. There will be data and #Chartz and grid context! But the TL;DR – My system performed great! But did use lots of power. #heatpump (1/n)

Context: I gone the full #ElectrifyEverything! My 2400 sq ft townhouse has a Mitsubishi heat pump with resistance backup running in a ducted system. My @span_io electric panel monitors everything. See previous thread. (2/n)

https://twitter.com/ChazTeplin/status/1558915267614281728?s=20&t=hfijCTH4qxaS7uJpHRQNZw

It was cold last week, below -10°F in Boulder! So how did my system do? Most importantly, it kept my home comfortable. This chart show temperatures, set points, and power use. (3/n)

The vast majority of heating was provided by the heat pump, which worked well below 0°F. My controller added resistance heat briefly during the two coldest nights (Dec 22 and Dec 23). (4/n)

Total electricity = high! I used >100 kWh for heating on both Dec 22 & Dec 23. (Of course, a gas system would also use tons of energy!) Compare to my total daily (non-EV) power use of <24 kWh for most temperate days. Turns out that heating +70°F requires lots of energy! (5/n)

Now how did my grid provide that electricity? And more importantly, how could it supply my power as Colorado continues its decarbonization path? Here is Xcel’s generation mix on these days (from EIA) (6/n)

While coal/gas ran a lot, wind and solar played large roles. While cold, it was also clear. Solar, presumably from larger systems that protected themselves from the snow that fell overnight on Dec 21, performed well. Note that CO has deployed way more wind than solar. (7/n)

If we look at just wind and solar generation, we can imagine that more renewable deployment (especially solar) and some ~4 hour storage could have provided basically all the needed power during this cold spell. (8/n)

Of course, there are days when wind and solar output are low for longer periods and we may need more than today’s Li-ion batteries – but I think this “postcard from the future” shows just how far we can go even during challenging conditions! (9/9)