One of the things that we talked about in our energy posts was load shedding. That is, it’s perhaps cheaper and easier to shed loads than it is to buy a larger backup power system. That’s especially true if we are going to use a portable backup generator. Those units, having only 10 kilowatts or so of available power, require that we only power the most essential of loads: a refrigerator, a freezer, some battery chargers, and the like.
In my case, when we have had power failures in the past, I fill the refrigerator with bottles of water to increase the thermal mass and slow the rate of warming. Then we use the generator to power the refrigerator, the freezer, and a few other loads like battery chargers, TV, and a small air conditioner.
Like I said before, I feel like a prepper should be able to do better than that, so we are looking at entire home power sources, but it’s far cheaper to power fewer loads than it is to buy more power capability, and that is what we are going to look at today.
One way to do this is simply to go out to the garage and flip the breakers on the loads I want to get rid of. Or simply not turn them on. Or we could get a SPAN panel. After taking a careful look at my budget, my needs, and the panel itself, I don’t think that we are going to get one. The reason is that, at $5,000 installed, it is the most expensive way of shedding loads. Let me explain:
I have been analyzing my electrical loads for the past several weeks so I could get an idea of just how much power I will need. My loads break down like this:
- General household loads are about 3 kwh per day. That includes lighting, television, ceiling fans, and all of the vampire loads like clocks, cell phone chargers, and the like.
- My refrigerator in the kitchen is another 1.5 kwh per day
- The deep freezer in the garage is 1.1 kwh per day
- The clothes dryer uses 3 kwh for each load
- The water heater uses 7800 watts, and even with no hot water being used it sucks down about 4 kwh per day. That number goes up if you are using more hot water.
- The oven uses 3,000 watts.
- The cooktop uses 6,700 watts with all elements on
- The main air conditioner uses 6 kw, the upstairs air conditioner uses 3 kw. The big question is how often they run in the summer.
In the case of the smaller loads like the refrigerator and freezer: we don’t want to shut those off. That’s the entire reason why we have backup power, to preserve the food that is being kept cold. Those loads, combined with the smaller loads, are about 5.5 kwh per day.
You can see that most of the largest loads are ones that we have direct control over: the dryer, cooktop, and oven. If we want to shed some electrical loads, all we have to do is not use them. There is no need for load shedding there. The exceptions to this are the water heater and air conditioners, all of which turn on and off without direct input from a human. If we aren’t home and our backup power kicks in, we need to shut those loads off. If we are going to have an automatic power backup system, I believe that load shedding should also be automatic.
We can have some sort of automation to turn them off automatically whenever conditions dictate. I am opting for an automatic system with a manual backup. With that being said, there are cheaper ways to accomplish this. My air conditioners are already controlled by Ecobee thermostats, meaning that they can be controlled with a smart home controller like Home Assistant or SmartThings, or even through the cloud using IFTTT. For the water heater, you can get a smart water heater controller like this one, and use IFTTT to integrate it to your backup system, or you can use a smart relay and have a smart home controller to regulate it. These methods work just as well, and won’t cost you five grand to install. Then you can use the extra cash to add capacity to your backup system. In my case, that is most of the cost of another solar battery.
To sum this up: You can install two Ecobee thermostats for $149 each, and a smart relay for $164. This will give you automated load shedding for less than one tenth of the cost of a SPAN panel- saving you more than $4,000.
19 Comments
Birdog357 · April 8, 2024 at 10:43 am
Switching to more efficient gas appliances is a really easy way to load shed. My stove draws about 3 amps(120v) max when igniting… my water heater draws zero because it’s a continuous pilot. What’s your power bill look like?
Divemedic · April 8, 2024 at 11:00 am
You aren’t shedding the load, you are transferring it from electric to gas. Now instead of buying a larger back up electrical power source, you are now having to buy a larger gas power source.
While there are benefits to doing this, saying you are shedding the load isn’t really one of them.
Even so, there is no gas in my neighborhood. This means that I would have to have a propane tank, and that means burying one in my back yard. Now we are right back to paying lots of money for little benefit.
If you wanted to reduce the energy load of your water heater, the water heater controller that I mentioned in the post above is available for gas heaters as well as electric ones.
Birdog357 · April 8, 2024 at 7:50 pm
The only time my gas would fail is in a major catastrophe so I’m not terribly concerned about it. It is shedding an electrical load, which was the point of the post. It’s too late now since the house is finished, but propane for cooking and heating would be cheaper than doing it electrically since electric heat is the least efficient way to do it. My combined gas/electric bill(same company provides both) is always under $200/month year round. And we get deep cold in the winter and heat and humidity in the summer.
Noah Was Knower · April 8, 2024 at 11:04 am
I was thinking about that regarding rural bud’s hideout, how to minimize usage and make generator power last.
Wymyns always think that resources are unlimited so they would quickly bust that up.
Pappy had a 20 acre lot with nothing but those transformer towers in the wayouts of the southeast corner of the state and he would use the sulfur creek to store foods in a bag to keep them cold and bathing in it was actually good for the joints.
He had these 100 year old glass tubes with purple light that were used to help with arthritis by rolling over joints.
So sad he sold that acreage but he did move to FLA and resembled Ernest Hemingway at the end, even winning a lookalike contest.
The term cold hard cash is from The Depression where people would store money in an icebox, party like it’s 1929.
Icy Reaper · April 8, 2024 at 11:38 am
Dam, this series is becoming a graduate course. You should issue diplomas at the end:)
The water heater draw really surprised me though, it being higher than the AC even with no use. Have you considered a tankless electric water heater since gas isn’t a option in your area?
One other question for a non techie, a lot of the various systems today seem to be going to using a app on your phone to control things versus panels. if the power goes down for days or longer or the zombies start walking, wont the cell service be gone and thus the app will be useless?
Divemedic · April 8, 2024 at 1:26 pm
If you look closely, the switches that I am reviewing all have a manual, local override.
I Am adding some comments on power usage to the post. You should check it out.
It's just Boris · April 8, 2024 at 12:45 pm
For home automation, we’ve been using MiCasaVerde by Vera (succeeded by Ezlo, I suppose, but we haven’t migrated yet). One of the initial reasons was not needing a subscription; but another is not needing an Internet connection for it to function. Something to consider if using a home automation setup to help shed / reduce loads.
Divemedic · April 8, 2024 at 1:27 pm
That’s why all of my devices have either local control, or manual overrides.
However, it is far more likely that I will have a local or regional disruption of electric utilities while I am not home. I consider a widespread loss of utilities and Internet lasting longer than a few days as being an extremely unlikely, but high stakes disaster.
Still, prep as well as you can for the worst case, and you are ready for anything less.
It's just Boris · April 8, 2024 at 6:40 pm
Sure. My point was, though, that even if it’s only for a few days, you still might want to start the load-shed or -reduce process on things like the hot water heater when the power drops. If your home automation controller cannot operate without an Internet connection, it can’t do that for you if you don’t happen to be home at the time.
And if the power is out for an extended time, well, I might still like to be able to have all the house lights come up at one time, should something go bump in the night.
Rick T · April 8, 2024 at 1:46 pm
Generator sizing is a place where you don’t want to just stack up the nameplate ratings to determine your generator size. It is better to look at your energy bills to see what your maximum hourly usage is during the year, and probably best to have a solar energy consultant do a sizing study since they have the data to estimate realistic loads for things like your cook-top.
As one example you won’t be running all the elements in an emergency so 6.7KW isn’t a realistic load. Another is you may shut down the main AC unit and just use the smaller one for focused cooling.
Having a propane tank in your yard isn’t all bad, propane does not degrade like mordern gasoline so you have a stable energy source for the emergency generator, and propane burns very cleanly. 400 gallons (usable capacity of a 500 gallon tank) of propane can go a long way.
Divemedic · April 8, 2024 at 2:16 pm
Again, this entire series was meant to be simplified. I am trying to educate without turning this into a graduate level electrical engineering course.
I have not merely been stacking nameplate data. I have three months of daily usage from a smart meter, I have been analyzing usage using a Kill-A-Watt meter, and have been talking to at least seven different solar companies, including Tesla.
The sticking point is that there is no, and I mean no, data on what my summer usage will look like, simply because it is a new house and there is no data to be had. That makes estimating peak summer usage difficult, and at this point, simply a guess.
As to your point about propane- I don’t see the upside in my situation. Why would I bury a tank, trench the lines, and buy all new appliances and a propane generator, just to put in a system that will, no matter what happens, run out of propane in just a few days of running the generator?
We already discussed propane and a generator several posts ago. It may work for some people, but it just isn’t an option in my specific case. Here is what I said:
The real benefit to propane is in using it to cook or heat water directly. When you convert it to electricity, it ceases being as efficient or convenient, and you will eventually run out.
The reason I am looking at solar is that it:
– is effectively limitless, not needing fuel
– 30% of the cost is offset by tax breaks
– the remainder of the cost is offset by lower electric bills
– I avoid the cost of replacing my appliances
Overall, this makes the solar system much more practical and cost efficient.
Elrod · April 8, 2024 at 4:58 pm
If the plan is to have Power Source B which takes over automagically when Power Source A fails, that’s easily accomplished with a generator that starts automatically and an automatic transfer switch. I’d prefer that system rather than one which depends on me manually accessing and controlling the switchover from Remote Location X with ones and zeroes which, maybe, might not be available or just unable to make it all the way through to the device(s) being controlled.
And whether it’s called “load shedding” or “load management,” that’s one of the things transfer switches can do.
Random thought: When the house was being built did you request/demand an auxiliary circuit(s) (to be powered by a future generator, for example) that provides 120V in each room? Electricians wire houses the most convenient way for them, which is usually not the best way to manage distribution of (limited) alternate power.
Divemedic · April 8, 2024 at 7:20 pm
1 That is not the plan, nor is that what load shedding is.
2 Load shedding isn’t what a transfer switch is for, unless there are two power buses with one of them being dropped when the transfer switch switches over
EN2 SS · April 8, 2024 at 6:38 pm
My only comment on this thread is, get an inverter generator. They use considerably less fuel, either gasoline or propane. Cost more, but much more efficient.
Divemedic · April 8, 2024 at 7:25 pm
LOL. It’s almost like no one is reading these things.
EN2 SS · April 10, 2024 at 6:09 pm
What, I’m not allowed to add my two cents to the discussion? I simply posted a short opinion on using generators. That I have lots of experience with.
Divemedic · April 11, 2024 at 7:23 am
Did I tell you that your post was out of line?
Did I say that you can’t post?
No, but I am perfectly capable and willing to roast someone who is making comments that have already been repeatedly addressed in previous posts. Lighten up, Francis.
D · April 8, 2024 at 10:08 pm
I have been debating for the last 6 months on my hot water heater…go tankless, dig a trench, and hook it up to propane? Or do something stupid like flip the breaker off every night to conserve energy? (Or maybe just replace it–it’s ~15 years old and probably has 8 inches of rust in the bottom…)
It’s not in my budget to buy a tankless and trench propane to it at the moment (more damn taxes to pay)…but that link to an Aquanta might just be a decent solution. I’ll queue it up for next month’s budget and give it a shot.
Stefan v. · April 8, 2024 at 10:16 pm
In Australia there were many solar hot water heaters. If your big yellow sky thing is as powerful as it is down under, it would be worth looking into.
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