Intro Note: In the interest of operational security, some details are missing or slightly altered, without obscuring the learning points we experienced.
The Hurricane’s First Approach
Our family is very familiar with southeastern USA hurricanes from living in a “hurricane state” for many years. Somewhat inland, we generally have high winds but not significant structural damage. Usually, there are many, many trees/limbs down, causing havoc with roads and power systems.
As usual, the US Weather Service and the news media hyped Hurricane Helene to the max, threatening the usual utter destruction. We have learned to look at the National Weather Service maps and data ourselves. It looked like it could be bad, but the chances weren’t that high. (Normally, the predictions can change drastically in the final 24 hours before arrival.) Our local volunteer amateur radio group was alerted by the authorities, and we mustered sufficient volunteers to staff the required shelters, etc., including our county’s central control point, for the required length of time. This is a testament to our training and our dedicated volunteers — no one wants to leave their family when a big storm is approaching, but someone has to, in order to serve the community!
It looked like a big bad storm….but we’ve seen them before. I’ve served in multiple locations, and this time I was helping at the central control point, where we interface with dozens and dozens of public service employees from every department of our local government, from public works through law enforcement.
The storm came. Trees went down all over our county. Power was out to an enormous number of people in our state. With that, intersection traffic lights don’t work, and there can be accidents, too. And during the high winds, there is zero fire or ambulance response possible. You’re on your own! I kept very close touch with all our volunteers, and my loved ones have licenses and radio gear right in the living room. So it was easy to maintain contact. No power at my house, of course. But our radios still work!
Our county deputies are equipped with chainsaws in the trunks of their vehicles and they know how to use them. This is a huge force multiplier in making traffic flow in the aftermath of a storm. Our county response team uses huge computer databases and systems to track every problem the storm causes. Our radio volunteers are just “icing on the cake,” positioned at designated points, to provide backup communications, and in addition we serve a pretty good number of amateurs at their individual houses looking for and providing information from all over the county, especially when the winds are too high for law enforcement to roam and report.
As the storm passed and dust cleared, I was released to head back home, and managed to get there to reunite with loved ones. Now the real work began.
What got us to put in Solar
Some years back, we had a storm that knocked out power to our home for 10 days or more. That was an eye-opener for us, with very limited other power assets. I was repairing a generator on the kitchen table to try and help a neighbor and running my own into the ground to keep refrigerators et cetera going at my house. We decided it was time for more substantial preparations. Within a few years, we had a very substantial amount of propane available to us, and we also had a very large solar power system with a quite large battery system, using high-quality lead acid flooded cells. (This was before the development of lithium ferrophosphate batteries.) From then on, power outages for our home were much more tolerable, because we automatically had power for “life-safety” portions of our home. We would look out to see if the neighbor’s house was dark, to determine if the power was out. Our neighborhood is on the fragile end of some long power transmission line, and thus goes dark quite often — but not our house.
Well, this hurricane taught me a few new lessons. Little did I know that I would get hit twice.
Something Isn’t Right
Right after the storm, we did fine on the batteries and meager solar power from the sun with heavy overcast, and all our refrigerators/freezers were fine. We live in a relatively hot portion of the nation. The old and the young do not do well with temperature extremes, and the elderly are particularly at risk when high temperatures are uncontrolled by air conditioning in hot parts of the nation. (See for example: https://www.nia.nih.gov/health/safety/hot-weather-safety-older-adults and https://magazine.hms.harvard.edu/articles/effects-heat-older-adults.)
The “locked-rotor-amps” rating of our central AC unit is prohibitively LARGE so there is no way we are going to run central air during a utility power outage. We do have a smaller inverter-based AC system in one small section — but this newer technology has proven to be unreliable, with expensive microcomputer failures quite frequently, so we avoid using that system as much as possible! Our simple temperature control defense is small window-mounted air conditioners. We keep two available. They produce about 5,000 BTU worth of “cool” and consume a steady 500 watts. With reasonable power generation, 500 watts for many hours of the day is well within reason. It allows us to have a cool bedroom, stay healthy, and sleep well after a major storm. It isn’t infrequent that our spare window AC unit gets loaned out to family in the area and is a huge blessing to them.
We can cook with our choice of outdoor grill (propane), indoor microwave or crock pot. And we have the usual prepper set of a very diverse array of foodstuffs, from fresh, to frozen, canned, dry-canned, and freeze-dried. We don’t bother to head to the jam-packed stores when a storm is coming. People can get hurt at those chaos zones even before the storm arrives.
Because we have a very diverse set of food storage with a significant amount of food, we have multiple refrigerators and a deep freezer as well — in our hot portion of the country! My experience is that these refrigeration systems tend to cycle on and off with a duty cycle of about 33%. They don’t use a lot of energy when running, but their induction motors require a huge 15-20Amp AC spike of current to start. I usually figure an average of 75-100W for a normal fridge and freezer. Our lighting power consumption is very, very minimal, with highly efficient LED lighting everywhere. But you can see that while we have lots of preparation for power loss, even without the central air conditioning, we need around 0.5-0.6 kW average per hour, and that is 12-15 kWhr per day of energy. If we have less than that, we have to start emptying refrigerators and shutting down power loads.
So I was beginning to observe something that I hadn’t counted on: The overcast was lasting several days, not just one or two. I watched nervously as my batteries’ state of charge oscillated up and down each day, but with an overall definite trend downward. So it was time to come up with alternate charging!
I plugged in the 48V fancy charger I had bought just for this purpose years before, but never tested. I powered it from our propane generator from a nearly inexhaustible supply. It is a little more work, but I can also connect the propane generator directly into a 2nd transfer switch separate from the solar system and power some life-safety portions of the house. Making that switch to propane generator power requires moving a long, heavy cable from the transfer switch to the location of the generator (constrained by the propane supply line). In retrospect, I should have taken that step earlier! It would have greatly decreased my dependence on solar power and avoided some of the issues that developed.
Unrecognized Limitations
Turns out that the previously untested 48-volt battery charger had two drawbacks I didn’t quite foresee. First, at best it only puts out a maximum of about 0.75 kW. That’s nice, but a small fraction of what the solar system produces on a sunny day. It would need hours and hours of generator time. And nowhere close to fully utilizing the potential energy from the propane-fired generator. Worse, it was a computerized battery charger, expecting to see the steady rising voltage changes of a healthy battery under charge. If anyone turned any significant power draws on, or off — the resulting variation in battery voltage confused the computer badly, and it typically decided it was no longer connected to a “battery” and would cease to charge without notice!
It became a real problem to try and keep the computer “happy” by arranging nearly constant power draw from our inverters, just so the computerized charger would continue to charge. With its limited power output, and requirement for limited changes in power usage, this wasn’t going as well as I wanted.
A Mistake
Then I made a mistake. My wife has ONE big request during long power outages: a hot shower! I have one electric water heater set up on life-safety power just for that need, and early one morning, I turned the power from our struggling batteries toward that hot water system and she got her beloved shower…. but I failed to notice that there was a crucial dip in the battery voltage, and one of my refrigerators wasn’t able to draw that 20-amp surge current to start its compressor. You couldn’t tell it from observing the power control system unless you had looked very closely at the error messages, which I didn’t….but we would discover the defrosted freezer many hours later… Ouch.
(To be concluded tomorrow, in Part 2.)
Read the full article here