Feb 2022 cold event

Living on the Edge 

The Feb 2021 event left me in a world of hurt.  5+ days below freezing.  Lost water supply in the first 24 hours.  At the time, I was able to tend a wood stove fire; I burned a lot of wood but the warmth of the house was not seriously threatened despite the grid failures.  Eventually, I found about 6 steel pipe breaks under the house.  I VERY slowly recovered.  First, getting cold water in bathroom only after a couple of weeks.  Had to rig an outdoor shower with a 120v water heater.  That served me several months.  Eventually, I found a plumber willing to work and he, eventually, got normal water in the house.  As I recall, that was late summer.  "Normal" being hot water in bathroom sink and bathtub, in kitchen sink, and to clothes washing machine.  Cold water in bathroom, kitchen, laundry room.

For 2022, a ~2 day ice storm was forecast.  Not wanting to have to tend a fire, I had installed two mini-split hyper heat pumps.  12k and 9k btu.  Those turned out to be insufficient to keep the house very warm under the experienced conditions.  A 3rd (18k btu) unit is ready to install.  The big threat this episode was  ice induced local power failures.  That did not happen but I was prepared to burn in the wood stove.  The wood stove was held in reserve in case of the power failure.  The Power Wall carried me through (barely) the power failures of 2021.  The PW now goes into "storm mode" when the forecasts indicates.  Normally, the PW charges only from PV power.  In storm mode, it additionally charges from grid power and does not discharge while grid power is up.  That is, it tries to maintain a full charge in order to be prepared for a power failure.

The event started early Wednesday morning.  Early Friday morning, the lowest observed temperature was about 24-25.  I lost water supply in the early morning hours of Friday.  I think/hope the frozen place is at the pressure pump about 1/3 of a mile from the house.  Most of the ice failed to materialize and I had no power failures.  I had some concern about poor PV performance due to ice covered panels; we had relatively little ice.  The sun came out before noon Friday and I briefly observed about 24kw of PV production.  Recent "good sun" production has been only about 21kw.  So, the ice seems not to have limited PV production.  The PW has remained at near 100% charge for more than two days.  I have some PW augmentation that might double the capacity of my (still single battery) PW to near 30kwh.  BUT, I have been pulling about 5kw to try to keep the house warm.  In the event of a power failure, I could not expect the PW to take over for longer than about 6 hours.  I believe power failure risk has now declined to near zero.

If/when I get the 3rd heat pump installed, I should be able to keep most of the house warm down to 5-10 deg.  I need to keep working on increasing the number of PW batteries to three.  I'm near to committing to replace several of my 1940s vintage double hung wood sash windows.

Over the past few years, I've experimented with using EV batteries to augment the PW battery.  Tesla has resisted making it easy to use their cars for V2H (vehicle to home; powering a home from the car).   It can be done but only through the DC-DC that supplies the 12v battery.  That power source is limited to 1-2 kw.  Ford seems to be promising V2H capability for their announced EV pickup truck.  IF Ford delivers and Tesla does not, I will buy a Ford.  Individual PW batteries have a capacity of about 13kwh.  Both Ford and Tesla pickup trucks should have 100+kwh batteries.