So we are four days into operation of the solar equipment. Right now, we are operating on a limited basis, more on that in a moment. I am not home because we are on the road, but both air conditioners, all vampire loads, and the water heater are running.
Output
We chose a system that is 10 kilowatts DC. That translates to about 8600 watts AC. The system begins generating electricity at about 9am, and reaches a peak of 8kw at around 10:30. By 1pm, the Powerwalls are fully recharged from the night before. At that point, there is no place else for the generated power to go, so system output drops to match whatever the house is using. More on that later.
We haven’t used any electricity from the grid since the sun came up on Friday morning. That indicates that I have enough panels for my house.
Storage
There are two places that I can store the power I generate. One of them is in the Powerwall, which has a total capacity of 27 KWh. Right now, I am maintaining a minimum of 30% as emergency backup, and using the rest to compensate for lower output at night or overcast conditions, or to make up for transient high loads, like when both air conditioners and the water heater are running at the same time. The advantages of using the battery are that the power stays within my home, and losing the grid means that I can still access it. The disadvantage is that the upfront cost of batteries is high.
The second place that I can store generated power is in the grid. The electric company buys my excess power in the form of credits that I can redeem when my system can’t keep up with the loads that I am placing on it- nighttime, stormy weather, or when loads simply exceed what I am producing. The advantage of this is that the upfront cost is low, but the disadvantage is that it relies on the electrical grid for redemption.
I can’t use the grid as storage because I don’t yet have permission to operate (PTO) from the power company. I should get it within two weeks after our final electrical inspection, which is supposed to be this week. So we should be fully operational by August 9.
Results So Far
Each day, we are generating between 35 and 45 kWh before panel output is reduced when the batteries are full. The solar energy being generated is directly running the house during the day, with the rest charging the Powerwalls, which run the house at night.
The water heater is using 4 kw when running, the upstairs AC is using 1.5kw, the downstairs AC uses 2.7kw, and the rest of the house uses 0.3kw. Since the ACs and water heater don’t run all of the time, the panels are more than capable at this point of keeping up by charging the batteries during the periods when the large appliances aren’t running.
The solar power system was installed this week, We turned it on this morning. 24 panels, each capable of supplying 420 watts, for a total capacity of 10 kW. We can’t yet sell the power back to the power company, because they haven’t yet approved our application. Until then, we will run off of batteries and solar, with the excess being given to the power company free of charge. Hopefully, that will change within a week or two.
The install took two days, even though it was supposed to only take one. On day one, the team got the Powerwalls mounted, and 21 of the 24 panels on the roof before an incoming afternoon thunderstorm stopped work for the day. On day two, they got the final three panels up, ran all of the conduit and wiring, then shut power off to the house for about an hour so they could make all of the connections. They turned the system on, but that was at 1700, after it began raining again, so we didn’t generate any solar at all yesterday.
At 1000 this morning, we were generating 5 kW from solar while only using 0.5 kW, with the 4.5kW of excess going into the batteries. Our Powerwalls are already charged to 50% of capacity, and we have already generated 6.5 kWh purely from solar.
I will revisit the numbers within a week or so. It’s still to early to talk about how well the system is going to meet our needs.
Our series on preparedness continues. We have looked at records, did an extensive (and ongoing) examination of power, and now we move on to medicine. When people think of medicine, they think of the sexy parts: usually trauma. Yeah, using a ballpoint pen and a pocketknife to open an airway in someone’s throat makes for great television, but isn’t really something you are going to have to do.
Trauma is a surgical emergency. The only thing I can recommend with trauma, beyond first aid is stabilize the injury and get the victim to a location that is equipped and able to perform the necessary surgery. If things have gotten to the point where that isn’t possible, the victim probably isn’t going to make it. To stabilize the patient, it helps to have a decent first aid kit like this one. Here are the basics of how to treat a gunshot wound from a talk I gave at the 2021 Florida Blogshoot. There are all sorts of people that will tell you to carry IV equipment, BVMs, and all of that, but frankly, you don’t need that stuff. There are plenty of studies that bear that out.
I have seen medical bloggers insist that you need to stock a room full of sterile, disposable dressings. Hogwash. All you need to do is cut up some old sheets, put them in a pot of boiling water for ten minutes, wring them out with hands freshly washed in clean, potable water, then dry them in the clothes dryer. Now you have clean bandages.
No, the important medicine that you need are the less sexy parts of the medical profession. The most important thing that you can have from a medical standpoint is knowledge. Start with a first aid and CPR course, something like First Responder or EMT. You can get an EMT certification in as little as two months for the cost of a single handgun. The more you know, the more you know, and one thing that you learn may be the difference between saving a life and not.
What medicines do we need? First, recognize that the biggest killers of people in a SHTF scenario will be contaminated food/water, and sepsis. Having things on hand to deal with those things will go a long way. So here we are with a list of medicines:
Iodine (Betadine will do)- wound disinfectant
Soap- cleanliness prevents infection
Rubbing alcohol- disinfectant
Vinegar- it can be used as a disinfectant
Loperamide (Immodium)- diarrhea is a huge killer, as it can cause severe dehydration and electrolyte imbalances
ondansetron (which is a prescription drug) and meclizine (over the counter) to prevent vomiting. They are dangerous for the same reasons that diarrhea is.
Acetaminophen (for fevers)
Ibuprofen (for inflammation)
hydroxychloroquine and ivermectin (for parasitic infections)
if possible, grow an aloe plant. Aloe is useful for burns and as a powerful laxative. If you can’t have an aloe plant, you need some burn ointments and a laxative.
hydrocortisone cream for inflammatory rashes
diphenhydramine, both pills and ointment
triple antibiotic cream
the following five broad spectrum antibiotics: augmentin, ciprofloxacin, doxycycline, metronidazole, azithromicin
Pseudoephedrine (Sudafed)
Aspirin
Famitodine
Clotrimazole cream
Those will handle most of what you will need in a SHTF situation.
IcyReaper wants to know more about the panels that we selected. I checked through the previous posts and realized that I hadn’t talked about them at all. The PV panels are the heart of any solar system, so let’s review them.
When considering which manufacturer I wanted to go with for our PV panels, we wanted to go with a large, reputable panel manufacturer. SunPower, REC and Panasonic are three manufacturers widely known for producing some of the highest quality solar panels with low degradation and good warranties. For that reason, they cost up to 30% more, but I wanted reliability.
Although REC was originally a Norwegian company with a good reputation in the industry, their panels are actually made in Singapore. The company has been bought and sold several times, and is now owned by another company headquartered in India. The company makes panels with higher efficiency and more output at up to 470 watts per panel, but they are more expensive than some of their slightly less efficient models. It winds up costing more to get the extra output than it would to simply add more panels, and roof space isn’t an issue for me, as I have a lot of sun facing southern roof to work with.
We decided on the REC Alpha Pure 2 panel for our PV panel. The spec sheet can be found here (pdf alert). The panel is 1.8 meters by 1 meter, and has an output of 420 watts with an efficiency of 22 percent. It has a 20 year warranty and has been tested as retaining 92% of its rated output at 25 years. If the REC panels are installed by a certified installer, the warranty is extended out to 25 years. You can read a review on REC panels here.
REC solar panels operate at high efficiency, have a low 0.25% annual degradation rate and come with an excellent 25-year performance, product and labor warranty. As I mentioned in earlier posts, the panels are designed for 140 mile per hour winds and hailstones of up to 35mm. In my book, that made them durable enough to withstand some serious weather.
The panels look nice, because they are pure black with no light colored lines. They simply look better than the older panels.
The disclaimer: I don’t advertise, and receive nothing for my reviews or articles. I have no relationship with any products, companies, or vendors that I review here, other than being a customer. If I ever *DO* have a financial interest, I will disclose it. Otherwise, I pay what you would pay. No discounts or other incentives here. I only post these things because I think that my readers would be interested.
It’s been a busy week here at the Sector Ocho support facility. Aside from working three 12 hour days, I also had two days of training tossed in, for a total of 52 hours this week. Let’s see if they pay the overtime or not.
I also got the final engineering report on the solar project. The 24 solar panels have a total surface area of about 500 square feet. That works out to 46.5 square meters. The panels have an efficiency of 22 percent, meaning that we generate a maximum of 10,260 watts at full daylight (full, direct sun is 1,000 watts per square meter). What is interesting is that even in heavy clouds, we still get 230 watts per square meter of sunlight here in Florida (I measured it), and the panels will still produce more than 95% of full output at that light level:
The panels themselves are rated for wind up to 140 miles per hour, and hailstones up to 35mm in diameter.
Now that the engineering report is done, we are applying to the electric company and the city for our operating and construction permits. I have to clear out one side of the garage for the wiring, panels, and mounting of the Tesla powerwalls. Installation should be within the next two to three weeks, depending on permit times.
Here we are, in the summer. Time to revisit our calculations on power consumption for our planned solar installation. Here is the usage data, combined with temperatures for the month.
January: Average use was 27kwh per day. Average Temp 60 degF, High 82 degF, Low 35 degF
February: Average use 27kwh per day. Average Temp 61 degF, High 87 degF, Low 37 degF
March: Average use 22 kwh per day. Average Temp 69 degF, High 89 degF, Low 43 degF
April: Average use 20 kwh per day. Average Temp 71 degF, High 92 degF, Low 48 degF
May: Average use 36 kwh per day. Average Temp 79 degF, High 98 degF, Low 63 degF
You can see that electric use varies with the temperature. The hot months of summer are going to be more costly in terms of electrical use, but that is somewhat offset by more daylight hours. I will continue using the estimated figure of 48 kwh per day. If we assume an average of 6 hours of peak daylight per day, then we need to be generating about 8 kw per hour of daylight. Since I am pricing out 9.6-10 kw of capacity, I think that I am right where I need to be.
Now I need to figure out how much battery capacity I need.
Let me repeat the following disclaimer, mostly because people keep commenting and asking me why I didn’t discuss power factor, some other brand of solar or batteries, or propane. I did research on batteries, and I don’t want to spend all of that money on propane that I will just wind up having to convert to electricity for air conditioning, anyhow. The numbers just don’t work (see the above posts as to why they don’t)
I sell propane and propane accessories. Solar is teh devil
You engineer types, this is a simplified discussion that was designed to give you all of the information that I considered and discovered in my research for a backup power source without bogging you down in details that are largely irrelevant. I am trying to keep things easy to understand, so spare me the discussion about how holes move. I am also excluding things like power factor, vectors, and other things that needlessly complicate the discussion.
Also remember that each person’s situation is different. Compare my climate situation to a fictional person in Starke County, Indiana (all weather data from best places) as an example:
While I have mild winters, hot summers, along with lots of sun and humidity, another person living in Starke county, Indiana might have cold winters, less sun and humidity, and warm summers.
Indiana gets 34 inches of snow per year, I get none.
Indiana has an average summer high of 83 degrees. Central Florida, 94 degrees. I see 90 days per year where the temperature rises above 90 degF, Starke County Indiana sees 9.
Indiana has an average winter low of 16 degrees, Central Florida, 46 degrees.
Our guy in Indiana has 129 days where the temperature goes below freezing and 6 days spent below 0 degF, I have 6 freezing days and the temp never goes below 0 degF.
Indiana has an average summer humidity of 62 percent, winter of 20 percent. Central Florida has an average summer humidity of 73 percent and winter of 50 percent.
Northern Indiana averages 4 peak hours of sun per day. I average 5.2.
Where I have 232 sunny days per year, our fictional guy in Indiana has only 170. Combine that with clouds, sun angle, and other factors, and our guy in Indiana gets 30-35% less power from sunlight than I do. You can calculate your own by looking here.
For those reasons, solar makes more sense here than it does in northern Indiana. Your mileage may vary.
I don’t need to heat much in winter, but I need to do significant cooling in summer. Maybe your area is different- each of us has to do our own calculations and studies, which is why I posted so many posts about my decision. I have spent quite a bit of time looking into this, and you should, too. It’s a large investment, and not to be taken lightly.
What are We Getting & Who is Installing It?
We have decided to go with a hybrid solar system (meaning solar with batteries) and we know roughly how large of a system we need, now its time to get more details.
At this point, we will look at which system we are installing, and who will do the installing. One of the things that I noticed is that solar companies are better at selling solar than they are at anything else. They will play this sort of shell game with you- they mix in financing, tax credits, and other facts, overwhelming you with information to disguise the true cost of solar. It’s worse than buying a used car. That’s kind of what spawned this series of posts. I wanted to organize the information in my own mind, while at the same time helping others to cut through the bullshit.
In researching for this buy, I talked to a dozen different people in my area who already had solar, including three people in my neighborhood. My wife and I have a somewhat left leaning friend who bought the empty land next door to his home about a decade ago and put in a ground mounted solar array because he is worried about being green. We consulted him because, hey, a decade with solar. Yeah, he’s a lefty, but not hard core. He’s also a veteran and a nice guy. His advice was helpful.
We also looked at online customer service reviews, a ton of reference materials, and we consulted with the sales people of half a dozen solar companies. Manufacturer’s websites were also referenced. This article is a summary of what I have found out after two months of research.
The Batteries
We know that we want system rated between 9 and 10kw, but how many and what kind of batteries do we need? The 900 pound gorilla in the mix is Tesla. The Powerwall 3 just came out, and it has some impressive numbers. It stores 13.5 kwh of power, and can deliver 11kw continuously, which would drain the entire battery within slightly more than an hour. The company is claiming a brief surge capacity of up to 30kw, which is pretty outstanding. Still, that amount of power isn’t going to be enough to run the house in a grid failure without cutting to essential loads only. This means that we will likely need two of them. Batteries aren’t cheap, but we will get to that in a bit. Two batteries will mean we can deliver up to 22 kw continuously, and will have a total storage capacity of 27 kwh.
The Tesla battery has some nice features. The battery itself comes with an inverter, the gateway, and the backup relay that will isolate the system from the grid in the event of a power failure, so we won’t need to purchase any of that separately. Each Tesla Powerwall 3 can support up to 3 expansion battery packs. The expansion has the same capacity as the main one, meaning that a Powerwall 3 and and expansion pack gives you 27 KWh of storage, while two expansion packs would give you over 40 KWh of storage.
I have looked at other batteries, but none of them had the power specifications that were as good as the Tesla, and the ones that did come close were in the same price range or were even more expensive, so I have decided to go with the Tesla Powerwall 3.
Florida Law and Solar
Florida has laws classifying the size of a solar installation.
Type 1 systems are solar systems that produce 10kw or less.
Type 2 systems produce more than 10kw up to 100kw. If you have a type 2 system, you are required to carry a $1 million liability policy. We already carry this much insurance, so it doesn’t affect us, but just be aware that the requirement is there.
Type 3 systems are those that produce more than 100kw. I don’t know what the restrictions are, and didn’t bother to look them up because 100kw would take more space than I have on my roof.
*Note: The sizing tiers established by Florida are measured in alternating current (AC) wattage, whereas solar companies measure the size of solar systems in direct current (DC) wattage. For comparison purposes: 10kW (AC) system = 11.7kW (DC) system. The difference is caused by technical reasons that we won’t get into here.
Summing Up Our Specifications
These quotes are for a system with 24 PV panels for a total of 9.6 to 10 kw unless otherwise noted.
2 Tesla Powerwall 3’s for batteries are included, unless otherwise noted.
We also priced a Powerwall expansion, but it isn’t part of the quote.
This will give us an average capacity of 35 kwh per day in the winter and 52 kwh per day in the summer, with 27 kwh of storage and the possibility of more, if we later decide to add expansion batteries. (One neighbor has four Powerwalls, and tells me that this is far too much. He said he let the salesman sucker him into spending $40,000 on batteries.)
This should enable us to power the house without input from the grid, especially if we turn off loads that aren’t essential. Things like the clothes dryer, a potential pool pump (if we get a pool) and other luxuries can be shut off if the grid is down and the PV system isn’t generating enough power. We are planning on putting the pool pump, if there should be one, on the non-backup power bus.
Fortunately, we have a pitched roof with a rather large, unshaded southern exposure and a great pitch angle, which will ensure that the panels will get the maximum amount of sunlight. There is plenty of room there for the 200 square feet of PV panels we will be installing.
Power companies in Florida won’t allow you to install a system that produces in excess of 10% more than your average annual electric consumption. The good news is that they can’t tell me what my annual consumption is, because no one knows that yet.
The batteries will be mounted to the inside wall of the garage, next to the breaker box (load center). The remainder of the electrical equipment will be installed on the outside wall of the house, next to the utility meter. The PV panels will of course be on the roof.
Tax Credits
As I have mentioned before, the IRS has a non-refundable tax credit of 30% of the cost of a solar system. This gives you sort of a rebate on next year’s taxes that subsidizes nearly a third of the cost of the system. Many companies use this to make it appear that the system is cheaper. Make sure that you get the bottom line cost before this tax credit is applied, so you know what it will cost you without confusing the issue.
In Florida, solar systems are exempt from sales taxes, and any value that the solar system adds to your home is not subject to property taxes.
None of the above tax credits are available to fuel powered generators, and was a big reason for me not going in that direction. The tax advantage gives installing solar more than a 37% pricing advantage over a standby generator.
Selecting the Installer
One of the problems that we had when we first bought the house is the number of door to door salesmen who came around, trying to sell us solar. Then there were the phone calls and attempted over the phone sales. I have a policy of not doing business with anyone who calls me without me contacting them first. I have found it to be a great way to prevent scam artists from making you into their next mark. Let’s begin with the technical specifications, then see what the costs will be.
I am not comfortable cutting holes in my roof, so this system is going to be installed by a professional. In my case, I contacted a few installers to get some rough quotes. Each quote includes two Tesla Powerwall 3 batteries unless otherwise noted:
One quote was directly from Tesla. They subcontract out the actual work, and only use Tesla products. Their quote for a system delivering 9.7kw was right at $42,180.
The second quote was from SunPower, another national provider. The salesman missed our first telephone conference, but called several days later to reschedule. They also subcontract out the actual installation. They do not use Tesla batteries, but use their own in house brand of battery that has similar but slightly less powerful specifications. Their quote was $52,880 for a 9.2kw system. They pushed hard for me to get a system with no batteries at all to cut costs, but that would make the system useless for power failures- the entire reason why I want this. The attempted hard sale of something that I told them I didn’t want and the high price were turnoffs.
We got a quote from a local electrical contractor who has been doing solar for about 20 years. They came recommended by a neighbor who had solar installed by them. Their quote to install a 10.1 kw system was for $43,147.
We tried to get a phone interview and a quote from a mid sized Central Florida solar installer. He was supposed to call at 12:30 in the afternoon. His secretary called at 1:00 and told us he was running late, and would call in about 15 minutes. The didn’t call until after 2pm. When he did call, he asked a few questions then promised to send over a quote with the promise: “I am going to make your choice an easy one.” The quote still hadn’t arrived a week later. He sure did make it easy to not choose his company, so that’s a promise kept.
One more regional solar company was contacted. Let’s call them Bidder 6. They are not a Tesla dealer, but instead wanted to sell us another brand of battery. He tried telling us that we needed 4 of the batteries he was selling. His batteries were Enphase batteries that store 5kwh each with a peak of 3.7KW of surge. That means these batteries are roughly 1/3 as powerful as the Powerwall 3 and I can get more storage with a pair of Powerwalls than from 5 of his batteries. When I insisted on Powerwalls, we were quoted a pair of Powerwall 2’s at a cost of $14,250 each. He also said that we need a minimum of 30 to 45 PV panels because our home was going to use an average of 30KWH per day in the winter and 60 to 75 KWH per day in the summer. When I pointed out that this house was only using 23KWH per day this past winter, he replied that it had been a mild winter this year. At the end of it, his quote was three days later than promised and was for an 11.2KW system with two Powerwall 2’s, and the quote was for $59,900.
So now that we have contacted seven different installers and gotten quotes from five of them, we know that the quotes ranged from $39,000 from Tesla, all the way up to $59,900 for Bidder 6. With the 30% tax rebate factored in, the quotes look like this (from least to most expensive):
Tesla $29,526
Local Electrician $30,203
SunVena $34,062
SunPower $37,016
Bidder 6 $41,934
Each of the installers offered a written warranty that was substantially similar:
25 years parts and labor that the PV panels will still produce at least 92% of their rated power.
For the Tesla batteries: 10 years parts and labor that the batteries will store 70% of their rating
For the other brands: 10 years or 8,000 charge/discharge cycles for parts and labor that the battery will store 80% of their rating specifications
The big exception to the above warranty was Bidder 6. Their warranty was for 50 years parts and labor that the PV’s will still deliver 75% of their rated power.
Our experience
The Tesla guy consulted with us by TEAMS video call. He didn’t know anything about solar that was outside of Tesla’s product line. Their quote was nearly identical to the electrician, especially when you consider that the local electrician is offering a system with 400w more capacity.
SunVena sent a guy out who was the most knowledgeable of all of the solar company people that I talked to. I really liked the company. It’s too bad that his quote was $3000 more than the local electrician and $7000 more than Tesla.
The local electrician had the least polished of the presentations. The guy who came out knew about solar, he just wasn’t a salesman. However, he knew what he was talking about and had competitive prices.
SunPower was the one that frankly rubbed me the wrong way. He tried to push me into products I didn’t want. Like Tesla, the company only sold their own products an no others, and he seemed more interested in making the sale than he did in pleasing the customer. His price being $7,000 more than the electrician was the nail in the coffin.
Bidder 6 tried telling us that we needed at least 11kw and two Powerwalls, with the possibility that we would need 17kw and three Powerwalls. Now we are getting into a price point that I just don’t want to pay. His quote of $60,000 was simply way too high to be considered.
My Choice
So for the above reasons, the choice is between Tesla and the local electrician, with the electrician being ahead. I will ask them for more specific plans to see more details. This will require a more thorough engineering inspection of my house by them. Tesla is refusing to do a more in depth study unless we contract with them, so we are probably going with the electrician.
Since a standby generator would cost us in the neighborhood of $16,000, this system is slightly less than double the cost. We do get the benefit of vastly lower utility bills, though. Our bill will go from a winter $150 and an estimated $250 in the summer, all the way to the minimum $35 electric bill year round. That will save us about $2400 a year in utility bills, so the difference between this and a genny will be paid in about 5 years (counting the fuel that we won’t have to buy and the fact that long term maintenance for the genny is higher).
The timeline is tricky. We are trying to sell our old house, and will be using the proceeds to install our solar power system. The remainder of the proceeds from the sale will pay down the mortgage on the new place, then we will refinance to a 15 year mortgage, which will cut our house payment by about 70%. So we are waiting for the sale of the old house before we move forward.
We need some time to see what our hot weather electrical needs are going to be, and the delay for the sale of the old house will hopefully give us a better idea as to how much our summer bills will be.
For the time being, that means we are waiting until May or possibly even later before we are ready to sign a contract. That gives us time for engineering inspections, final proposals, and for us to get a better idea of what power we will need for summer air conditioning. Once we move forward, I will update this with any new information that we have. I will also do other updates to answer questions.
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.
There have been people who are saying that solar is unsafe because the batteries present a safety hazard. I was trying to keep the discussion here a simple one and not get bogged down in minutiae, but there are always people who want to make a simplified discussion more involved and complicated than it needed to be. Remember when I said that there was a lot of misinformation and outright bullshit out there?
A little bit on my background. First, I was a Navy Electrician’s mate. I spent six years being professionally trained on high voltage electrical systems. I didn’t work with batteries, but I did work with a lot of electricl stuff. No, I am not an engineer, but I still have the basics.
Second, I spent decades as a firefighter. I have Bachelor’s degrees in Fire Science, in Public Safety Administration, (even though it doesn’t apply here, Nursing), and am a couple of classes shy of a degree in Chemistry. I am also certified in HAZMAT to the operations level as a result of my time as a firefighter. Yeah, I was trying to become a Battalion Chief, and I was actively working towards that, so I took a lot of college.
Let’s take a look at fire incidents involving batteries. Fire departments in the United States track fires throughout the US using the National Fire Incident Reporting System (NFIRS). Every time a fire department responds to any incident, they file a report that sends data to this system. Every kind of fire is tracked, including those by batteries. This has created a huge database. The National Fire Protection Association (NFPA) is the industry group that publishes fire protection information. The NFPA sets the standards that battery manufacturers in the US must follow, and that standard is NFPA 855.
Lithium battery fires are caused by a phenomenon called thermal runaway. In these situations, the increased temperature in the battery triggers it to raise temperatures even higher. As a result, the battery may become too hot to touch, smoke, catch fire, eject gas, or explode. As with any battery, a solar battery could potentially cause a fire if it overheats. But the top brands have strict quality control and are very quick to do a recall if something is found to go wrong, which is incredibly rare.
The type of lithium-ion battery can make a difference, too. There are different chemistries that are used in lithium-ion batteries, for example lithium cobalt oxide or lithium iron phosphate, and some are better than others when it comes to the risk of overheating. The safest in this regard and least likely to experience thermal runaway, is lithium iron phosphate. LiFePO4 batteries are also the most durable.
The other key to ensuring safety is to make sure everything is installed correctly and that the various components of your solar system are compatible. In particular, the charge controller that manages the power flowing from your solar panels into the battery: an incorrectly sized charge controller won’t protect your battery from overcharging properly and could potentially lead to problems.
To ensure the safety of your solar power system and property you should only invest in dependable and tested solar lithium-ion batteries from a reputable company that are properly installed by an experienced installer in accordance with the manufacturer’s recommendations. Always research battery brands before purchasing, including their product reliability, testing processes, and reviews.
That is one of the reasons why I decided to go with Tesla Powerwalls and why I won’t install it myself. I don’t have the experience with battery systems to the point where I trust myself to avoid a redneck engineering situation where I put together a system that works, but creates a fire hazard.
The Risk
What are the odds of an installed lithium battery catching fire? While the NFIRS system doesn’t track fires in lithium batteries versus other kinds of batteries, it does have pretty good statistics involving battery fires in general. Nearly every fire that I could find involving a lithium battery was in a cell phone, e-bike, or e-cigarette. These sorts of small batteries present fire hazards because they are small batteries where space is at a premium, and they are not properly vented due to those size constraints. Different type of issue than the larger batteries seen in EVs and large scale storage batteries.
Factors in battery fires are easy to track. Overcharging these smaller lithium batteries is the cause of these fires. According to the CPSC, approximately 54% of residential fires involving batteries resulted from overcharging or charging with incompatible chargers. In other words, people charging their e-cigarette, e-scooter, or e-bike with a cheap Chinese charger that they bought at Dollar General.
The CPSC reported that 18% of battery-related residential fires were caused by physical damage to the device. Not going to be an issue with a battery that is in a sturdy enclosure that is bolted to the wall. The NFPA states that approximately 20% of battery-related home fires resulted from improper storage conditions.
That’s 92 percent of all battery related fires being caused by improper charging, improper handling, or improper storage. This simply isn’t going to be an issue with a professionally installed home battery system.
Outside of that there are a few EV fires, and one other incident in a town called Surprise, Arizona. I searched every database that I could, and found a very few fires involving large storage batteries.
The Surprise, Arizona battery facility was a fire in 2019 involving a 2 MWh battery facility that resulted in the injury of 4 firefighters. A 2MWh battery is about 150 times larger than the batteries we are discussing for a home solar system. The lithium-ion battery involved in this incident was commissioned prior to release of the current standard on large storage batteries: NFPA 855.
So avoiding all of the media hype, just what are the statistics involving batteries and fires?
Each year, there are about 9,300 fires that occur in the United States.
Tesla alone sells about a million EVs each year. There were 44 electric vehicle fires in 2023.
In total, there were 390 fires, explosions, overheating, or incidents of venting involving batteries of all kinds in the US in 2023, but once you remove the smaller batteries as discussed above, that drops to less than 100.
Worldwide, Underwriter’s Laboratories reports that there have been 51 injuries and 4 fatalities from large storage batteries since they began tracking them in 1995.
Considering that there are about 2 million homes in the US with solar storage batteries in them, seeing 100 fires per year means that the risk is extremely low: about 1 in 20,000.
The batteries in energy storage systems (ESSs) predominantly use safer lithium-iron phosphate (LFP) chemistry, compared with the nickel-manganese-cobalt (NMC) technology found in EVs.
The failure rate of lithium batteries is about 1 in 40 million.
LFP cell failure results in less energy release and a lower probability of fire. A LFP battery that fails is more likely to smoke than it is to catch fire.
So yes, about 1 in 100 fires in the US involves a large battery of some kind, with the majority of those being EV battery fires, and one known case of a home storage battery causing a fire in the past 5 years. The risk of a solar battery fire is exceedingly low, but it is possible.
What if A Battery Does Catch Fire?
The National Fire Sprinkler Association is an industry trade group that is responsible for tracking how fire sprinklers put out fires. This is a great resource for fires involving lithium batteries. While it is true that there have been several high profile incidents involving lithium batteries, the incidence of them is rare, as discussed above. That brings us to our next point:
A second statement was that Lithium fires are impossible to put out, so fire departments don’t even waste their time with them. That’s a surprise to me, after spending more than 30 years as a firefighter. The metal fires that gave me fits were magnesium fires. There are certain brands of cars that use magnesium in their transmissions that are hard to put out, and I hated car fires involving them.
One of the problems that I saw with vehicle fires in general is that many firefighters have trouble putting them out. The fire is usually in an area protected from water, and lobbing water on the roof or hood of a car from 30 feet away isn’t effective at putting out a fire in the engine or transmission. You need to get to the source of the fire for any sort of firefighting to be effective.
Still, let’s look at the available information. The National Fire Protection Association is the fire industry’s main source of research and information on fires and fire prevention. Here is what they have to say on the matter:
Water works just fine as a fire extinguishing medium since the lithium inside of these batteries are a lithium salt electrolyte and not pure lithium metal. Confusion on this topic stems from the fact that pure lithium (like what you see in the table of elements) is highly reactive with water, while lithium salts are non-reactive with water.
However, this is only true of small and EV batteries. I would not recommend fighting a home solar battery fire with water, because a home battery storage system will be energized with some relatively high voltages. Although there are some companies out there that are trying to sell specialized equipment for these fires, most of it looks like hogwash that is designed to steal your money. My bet will be on using dry chem and calling 911.
Conclusion
The risk of fire from solar batteries is rare, and I worry more about an ordinary electrical fire caused by the wiring in the wall or from a stove than I do from the solar or its associated battery system. The battery in my laptop is more likely to cause a fire than a solar battery.
