Going Off-Grid w/ Solar, Part 1: An Overview

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June 10, 2019

Talking about solar power and off-grid utilities is a sketchy subject, even amongst people who advocate for “self-reliance,” and “liberty.” It can stoke people’s anger, very, very quickly, I’ve found. I’m not exactly sure why that is, but I suspect it’s primarily three things.

First is, it smells like patchouli and unwashed hippies. After all, it’s “green” energy, right? I mean, it’s actually not, really, but, it is often marketed that way (we’ll come back to why it actually isn’t later). And, if you’re “green,” you’re obviously a nasty-smelling, foul leftist. Everyone who is a real conservative knows that we have enough coal and oil in the United States to keep our economy going for the next 500 years, without problem (well, except for the folks in the oil industry that actually understand how oil industry economics actually work, but again, that’s irrelevant to the current conversation).

The second issue about off-grid alternative energy is, it can’t save everyone. Alternative energy production, whether wind or solar, doesn’t pencil out well, at all, on the industrial scale. It works best on the small-scale, at the individual home, and—arguably—the small village. It doesn’t work worth a shit on the city, county, state, or national level. Many people, even in the “liberty” oriented “self-reliance” communities, seem to get really pissed when someone else finds a solution that allows them to live with some semblance of modern civility and utilities, even when a storm knocks out the local power (granted, my tendency, when someone announces that the power is out, to respond with, “Really? Weird, mine isn’t.” probably doesn’t help their anger management issue…).

Finally, and I suspect this is the biggest part, even though it’s actually the easiest to remedy, is the apparent cost of alternative energy installation. There are hundreds—if not thousands—of books available, dedicated to alternative energy. There are books on system design. There are books on component selection. There are books on installation. I’ve been reading books on alternative energy for well over 20 years, and I’ve barely scratched the surface. There are thousands—probably millions—of magazine articles, website articles, and even entire websites, dedicated to alternative energy systems, covering the same array of information.

Unfortunately, one the things I’ve noticed about the media available on alternative energy is, almost exclusively, it tends to tell people how expensive alternative energy is. I’ve seen books and magazine articles, in recent months, that insist a household PV system (PV stands for Photovoltaic, the proper term for the method solar panels use to produce electrical current) will start at a minimum of $10,000. I’ve talked to people who have had PV systems installed on their homes, and they invariably have paid closer to $20,000, and those were grid-tied systems.

In our local area, there are two or three different companies that advertise locally about their solar installation services. “Cut your electric bill to nothing!” “When was the last time you had a $15 electric bill?” (The basic hook-up maintenance fee in the local area is right at $15.).

I have a cousin who used one of their services, and had their entire roof retrofitted with solar panels, in a grid-tie system, hoping to reduce their electric bill dramatically (it’s the South. It’s hotter than three feet up Satan’s asshole here, in the summer). They did. He was stoked, when he got his first electric bill, and it was $22, when it had been almost $200 the month before. On the other hand, when I asked him what his monthly payment on the PV system was, and he said $400, he got a really crestfallen look on his face, when I started laughing my ass off at him. I don’t know how long the note is, and I don’t know what the interest rate is, but in his case, solar doesn’t win, especially since, if the power goes out…his goes out too. The utility companies generally don’t allow grid-tied systems to have battery bank support, because then, if the power goes out, your system is still charged, and could—theoretically—backfeed into the system, and kill one of their linemen.

So, grid-tied solar definitely does not pencil out, at the current time. Even though it’s sometimes marketed as being “more environmental,” because it “reduces the amount of fossil fuels the power company has to burn,” this is simply untrue. The power company has to keep the generators running, because they don’t know when a whole bunch of people are going to suddenly turn on their air conditioners or video consoles, and they’re going to need a very sudden upsurge in power. It certainly doesn’t pencil out for affordability and savings for the home-owner. Even if you paid cash for the system, it’s going to take you decades to get your investment back on electric bill savings.

Well, then why use solar?

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We chose an off-grid solar system for power for a couple of reasons. First of all, when it’s done right, it can actually be extremely affordable. For a rural location like ours, where the power company was going to have to install new poles and lines to reach our house, the cost of our PV system was dramatically less than what the power company wanted for the installation, and we don’t have ongoing electric bills on top of it. I’m kind of a cheap fucker. If I’m going to spend money, I want to spend it on things tangibles.

Second, we wanted reliable power. While our local utility is actually pretty decent, there have been a half-dozen outages in 2019 alone. We’ve had one, from a nearby lightning strike causing the breaker in our system to pop. While it took the utility company between 12 and 72 hours to get all the power back on, it took me 30 seconds to walk over and flip the breaker back on.

Third, we wanted resilience. Regardless of your position on Peak Oil, and other issues, the reality is, if the economy collapses—as it is showing increasing signs of doing, according to a wide range of economists with pretty solid track records, the power company isn’t going to make keeping power on to residences a priority. In the event of a CME or an EMP—both of which even the government is increasingly admitted are a matter of when, not if—the power company is going to be toast. Will a small-scale solar installation survive? Maybe, maybe not, but it damned sure has a better chance than the large utilities.

For all three of these reasons, a grid-tied system simply didn’t make sense for us.

I managed to build our system for less than $3000. It started out, when we were living in a portable shed, and building the house, with a single 210W, 12V solar panel, a cheap inverter off Amazon, three Marine/RV batteries from Wal-Mart that combined offered 330 amp hours of power, and a 700W inverted from the local parts store. The batteries were $70 each ($210). The solar panels was $105. The inverter was about $34, and the inverter was $70. We used that system for two years. At a total price of $429 (let’s round it to $450, to cover the cost of the wires and different connections I used), amortized over the 24 months we used it (I think we actually used it for 26 months, but…), our “monthly electric bill” was $17.49…the house we rented before, our monthly bill was $120 a month. So, in four months, we had broken even, and the rest was—literally—free energy, at that point.

Of course, that small of a system limited what we could run on electricity, if we didn’t want to kill the system of run out of power. In that shed, we had electric lights (and with babies in the house, we generally leave at least one light on through the night), two fans running through the day, in summer, and a smaller, 36” flat screen television and DVD player. We also charged laptops and cellphones. There were only 3-4 days, in that time frame, when I had to tell everyone to turn everything off, except the lights, because the batteries were low. In every one of those cases, I was able to hook my truck up to the battery bank, with a pair of jumper cables, and recharge the batteries, in an hour or so.

Our current system is significantly larger, but still smaller than most off-grid PV systems. We have six 240W panels, making our PV array a 1.4KW array. Most household sized units that I’ve seen are closer to 5-10KW. We have a 60amp SunnySky MPPT charge controller, an AIM 5KW inverter, and twelve 105ah Duracell AGM batteries, for a total storage capacity of 15.75KWH (105ah x 12.5V x12). Of course, since you don’t actually want to discharge the batteries past 50% capacity, really, we’re limited to roughly 7.5KWh of capacity.

The panels were purchased for something like $120/panel, for a cost of $0.50 per watt, which is, of course, significantly less expensive than the roughly $3.00 per watt of a retail price. The panels were new in the box, located via a Craigslist ad, by a friend (full disclosure: even though I was going to repay him for the cost of the panels, he ended up giving us the panels, so I actually didn’t pay for them. I’ve still included the cost of the panels in my overall cost estimates). They are manufactured by Trina Solar.

The charge controller, from SunnySky, was purchased after my previous charge controller, purchased via Amazon, for $50, turned out to not be a MPPT controller after all, and caught on fire one day, when the panels were producing more power than it could handle. Nothing better than smelling burning plastic, and looking frantically for what the source is, only to see your charge controller, right next to a bank of batteries, in flames! The SunnySky charge controller cost me something like $200, and has worked amazingly well for two years now, and has a much easier to read and understand digital display than the other piece of shit I had. The AIM inverter, even for the 5KW version, was only $400. That’s a total, so far, of $1320.

The battery bank was, by far, the single most expensive aspect of the system. After using a set of cheap Everlast Deep Cycle Marine/RV batteries for three years, including a couple of ill-advised deep discharges, we had two of the three batteries go bad. One was completely dead. It wouldn’t hold a charge over 11.2V. The other would hold a charge, but only at 12V, meaning it has lost half of its capacity (a fully, 100% charged 12V battery should actually be at 12.5-12.6V).

I contacted the local off-grid solar installer, and asked him for the price of an on-site consult. It turned out—unremarkably, given the local culture—that not only did we have a couple of mutual friends, he had actually heard of me, and was interested in looking at my system anyway. He came out, looked over the system, and declared it “good to go. I wouldn’t have done it any different, except…” he recommended a couple changes I already knew needed to be made, like getting my wiring from the battery bank to the house, either buried, or up off the ground, and that I needed to build a better structure to house my battery bank. For the record, both still need to happen…

I asked for a recommendation on higher quality batteries. Expecting him to recommend really expensive golf cart or forklift 6V batteries, I was pleasantly surprised to discover that he recommended—and used on his installs, unless the client specified something else—a simple 105ah glass mat battery by Duracell, that was available from Sam’s Club. I checked Sam’s Club, and the batteries were $179 each, plus a core charge of $10, for a total of $190. I have twelve batteries in the bank, currently. Total cost of the batteries was $2280, but I didn’t—be sure—buy them all at once. I started with four batteries, and then added two every two months, until I had ten. We used just ten for the better part of a year, before I finally went and bought two more.

So, thus far—including the cost of the panels, we’re sitting on $3600 worth of PV system. Of course, when you add in incidentals like wiring and connectors to put the system together, it’s probably closer to $3700.

That’s considerably less than the $5000 the power company wanted to extend the lines to our house, and I don’t have electric bills. For me, that was a no-brainer. We currently manage to run a 7.5 cubic foot deep freeze, lights throughout the house, a radio, the large flat screen television, a DVD player, three or four fans throughout the house in the summer, and we charge two cellphones, two laptops, four two-way radios, a shortwave radio receiver, and a few other things that escape me at the moment.

We have been using the current power system for pushing three years now. Amortized over the course of 36 months, our power “bill” comes out to $102. That’s not particularly impressive, until you start looking at the longevity of PV systems. It is currently expected that PV panels SHOULD have a working life span of 20-30 years, before there is a noticeable drop in power. Assuming we can get the expected 7-10 years of life out of the AGM batteries, versus the cheaper Everlasts that lasted three years, and absent a lightning strike that blows up the inverter or charge controller, we should get a solid four more years out of this system, without needing to spend more money on it, and probably more like another seven years. If we get the low end of seven years of life out of the batteries, we’re looking at a cost amortization of $44/month. If we get the full ten years, it drops to $30 a month.

It’s important to note that, while the AGM batteries don’t require maintenance, I do check the batteries monthly, with a voltmeter. Even after the amount of time we’ve been using this set of batteries, our batteries are still at 100%. We’re extremely careful to make sure we don’t get them below a 50% depth of discharge though. I’ve heard of people getting 15 years out of a set of batteries. While I don’t expect that, it would make me very, very happy.

Talking to friends in town, the average monthly power bill these days, in our area, is just north of $200/month. While the cost savings are nice, the bigger benefit on that front, from my perspective is, the system is already paid for. I don’t have to worry about making that bill every month.

More important to me, is the independence it offers me. One of our neighbors works for the county water department. Since we use rainwater catchment for our primary water supply, and have a composting toilet, and a greywater system, we don’t use the county water system. I was talking to that neighbor the other day though, and he mentioned that, at some point, I should expect that someone from the county was going to show up at our gate, wanting to inspect the property, for tax appraisal purposes. As he pointed out, they’ll see the place on satellite imagery. (To be clear, he’s 100% supportive of what we’re doing…and when I pointed out that if it was the Water Department that showed up, I’d know exactly who sent them, he hastened to tell me it wouldn’t be him, because he didn’t want to end up dead).

I responded that, there’s no building inspection/code enforcement in the county, so what were they going to, besides appraise it for taxes? He thought about it for a moment, and laughed. “Yeah, usually they threaten to have your power turned off, because you don’t have county water hooked up. That’s not going to work with you, is it?”

Nope.

Creating our own power offers a lot of independence. Developing our own water sources (we could do a well, but while local hand dug wells usually hit water at 10-15 feet, most of the drilled wells in the area are closer to 2000’, and we’re on top of the mountain, so it might even be deeper…and that shit is expensive!), with three spring-fed ponds for back-up (our water catchment system cost me less than $500 to build, and currently holds just over 1100 gallons), increases our independence. Local monthly water bills in the county are currently running approximately $105/month, so there’s financial savings on that front as well.

Finally, we get a lot more resilience out of our system than the local utility subscribers do. Our closest neighbor is ¼ mile from us, through the woods and across a pasture. Their power goes off for at least a couple hours, every time a storm blows in (and since we’re on top of the mountain, a LOT of storms blow in, at full strength), from downed lines. They are at the end of the power line, so they are hardly a priority for repair. As I mentioned previously, our power has gone out once this year, and it was a thirty second, effortless repair for me.

If the power grids go down for a longer term, our system will not last forever, of course. Batteries go bad eventually, electronic components short out or burn out. Solar panels can catch hail stones or thrown rocks, or other flying debris, and crack or break (PV panels are actually remarkably resilient though. Ours has absorbed golf-ball sized hail with no damage at all, even when metal roofs were dinged to Hell.)

But, our system does offer a more cushioned fall. We will be able to run lights a lot longer than others will. We will be able to keep our chest freezer running longer, facilitating much easier food preservation. We will have entertainment options for the children, beyond just doing chores and homeschool work.

Sure, a gas, diesel, or propane generator would allow us to do that as well, but not for nearly as long. Sure, batteries die, and while standard truck or car batteries are not particularly convenient for off-grid power applications, they will work in the short-term, and there will be a LOT of unused car batteries available, when nobody can get fuel for their cars. Even if an ad hoc battery bank like that only lasts six months or a year, with enough salvaged batteries, that gives the system a really long lifespan, even if the Duracell batteries don’t make the 10 year expected lifespan.

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We’ve been using a 5KW gas generator to to run power tools. Obviously this is not as sustainable or resilient as it could be. One of the fixes I have found is to begin switching as many tools as possible over to battery-powered tools. I was really hesitant to do this, initially, because of bad experiences in the past with battery powered tools, but I started with a couple of DeWalt cordless drills, and pretty soon found I also had a DeWalt cordless circular saw, and then a cordless Sawz-All, etc. I’ve not switched over completely yet (DeWalt doesn’t make a cordless angle grinder, that I’ve seen, and all of our power tools are DeWalt, except for a single Milwaukee hammer drill, and one Milwaukee circular saw that I’ve owned for twenty years.) I’ve been using the cordless tools an increasing amount, over the last two years, and have fallen in love with them. While I used my standard DeWalt circular saw for most of the work building our house, I don’t think I’ve pulled it out a half-dozen times since, for various projects, reaching for the cordless saw instead.

The battery pack tools are convenient, because I can charge them off the household electrical system quickly and easily, if not efficiently (think about it…the solar panels are charging batteries, which provide power to the house…which is being used to charge batteries. A better system would be to hook a PV panel directly to the batteries to charge them somehow. Unfortunately, I’m not smart enough to figure out how to do that….

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There are a number of things I’ve done “wrong” in developing our off-grid solar power system, according to the prevailing wisdom. Most obvious is, “don’t mix old batteries and new batteries.” Well, that’s fine, if you can pony up the money for all your batteries at once, or if you never have to expand the system’s storage capacity, but for the rest of us, it’s kind of a necessity. What I’ve found seems to work though is to simply check the status of the older batteries, before adding a new battery. If your old batteries are still capable of 95% or more of their new capacity, you’re probably okay adding new batteries to the bank, without worrying that it’s going to kill your new batteries.

I “fucked up” by purchasing “cheap” components, like the inverter and charge controller, that were Made in China. As I mention in the new Rifle book (shipping starts next week, for those who have pre-ordered, see the “Campfire Chat” article for this week), I see a lot of people who seem to use their rifle accessories as status symbols. “Oh, I’d never buy anything less than a US Optics/Scmidt & Bender for my rifle! Anything less is Made in China crap!” Never mind the fact that the photo they show of their rifle makes it abundantly clear the rifle is not used for regular, realistic training, but is a much-beloved safe queen. I see the same thing happening in solar discussions. “Oh, if you don’t spend at least $3000 on your Trace Inverter, you’re going to hate it, and your house will burn down.

Do you get what you pay for? Within reason, generally yes. Sure, a Trace Pure Sine Wave inverter would probably produce a slightly better form of electrical current than the AIMS modified Sine Wave inverter I have. Is the difference worth $2600? I don’t know, but it’s not to me. We manage to run a lot of electronics, on our modified sine wave electricity, that the conventional wisdom says we shouldn’t be able to, with no problems. I’d rather spend that $2600 on something else. Fortunately, I live in a place where off-grid living still generally means “no electricity or running water,” so even having a solar system is unique enough that I don’t need to “brag” about it. I don’t need to use my PV array as a status symbol. Hell, I built my house by hand, using traditional building methods. That’s bragging rights enough, as far as my neighbors seem to be concerned (we’ve had neighbors we don’t know, show up asking if they can check out the house, because they heard about it from someone).

I am going to expand the system. I have several more of the Trina Solar panels in storage under the house. My plan is to build a second, slightly smaller system, independent of the house system. I will put the freezer on the second system, and add a ductless “mini split” air conditioner to the house. A 24,000 BTU system can be found for around $1000 brand new, and I’ve got a local friend who got his used for less than $500. The cool thing about the mini-split is that they use considerably less power than a standard A/C, and the start up for the compressor is capacitated somehow, so it’s not a sudden surge that kills the batteries and overstresses the system. My family—and myself—will be grateful for the cool air, in another month, when night time temperatures are in the upper 80s, and humidity is at 90%.

The best part of switching the freezer to the new system will be the ability to put a regular refrigerator on the current system. We’ve been using a propane refrigerator for a couple of years now, because everything I had read claimed they were super efficient, and the most economical way to run a refrigerator off-grid. Unfortunately, they actually blow through a LOT of propane, and the local propane company won’t deliver to our house, because of the access road condition.

So, since we can’t get a 500 or 1000 gallon tank filled, we use several 100# tanks to fuel the cookstove in the kitchen, and 20# tanks to fuel the refrigerator. Our refrigerator—a deluxe side-by-side model from a RV—is reputed to be one of the better versions, but it only gets about 8 days out of a 20# tank of propane. I can currently refill a 20# propane tank for around $15, but when I have to do that four times a month, that starts adding up in a hurry. It would be more economical, as far as I can tell, to add a couple of panels to the array, pushing it up to a 2KW system, and a couple more batteries, and just use a regular electric refrigerator. Considering I can buy a used high-efficiency base model refrigerator for a couple of hundred dollars, and the propane fridge cost me $1300—and an eight hour round trip drive—it ends up penciling out better to just run the electric fridge, after expanding the current system. Now, if I could just convince someone to buy the propane fridge off me…..

A lot of solar “experts” insist that, for a household sized system, running a 12v system is uneconomical. They all recommend stepping up to a 24 or 48 volt system. We started out with the 12v system, because we were running such as small system. While I might get some more economy out of the 24 or 48v system, I can’t complain about the 12v system, and I already had the components. I may try 24 or 48V for the secondary system, for the freezer and A/C, but I really haven’t decided yet.

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Ultimately, I highly recommend going off-grid solar, if you live in a rural environment that makes it plausible. You’re probably not going to get to install and use an off-grid PV system in the middle of a city or a subdivision. In that case, I think a PV generator, with a single panel or two, and a couple of deep cycle batteries, that will keep your essentials running for a while, in the case of a mid-term power outage is a really solid idea. To me, it makes far more sense than a loud diesel or gas generator. Especially in a situation like a Hurricane Katrina situation, where you might want to keep stuff running in your house, without enticing looters, the silence of the solar generator offers some significant advantages.

Designing a PV system can really be accomplished two ways. The first—textbook—method, is to conduct an energy audit of what your current electric uses are, and then build a system to suit that, possibly with some oversize percentage built in, in case you need it later. This is also the most expensive way to design the system, outside of simply paying an outside contractor to come in and do it for you.

This method wouldn’t work for us, because we didn’t know what our usage was going to be. We knew we were giving up a lot of modern electronics—well, we thought we were—to go off-grid, and so we weren’t able to determine any sort of accurate figure.

We used what I call the “ol’ broke hippy” method of designing the system. We bought what we could afford, when we could afford it. When we had enough to cobble a small system together, we did. We used that, until we determined we needed to expand the system, then we added what we needed to get the desired expansion. This allowed us to take our time purchasing components, looking for the best prices and best components. There is a great book, available from Real Goods Solar, called “The New Independent Home,” by Michael Potts. It’s a series of case studies, from the 1970s-1990s, of folks who built off-the-grid houses and homesteads, using different methods and approaches. I read the original edition of the book in the late 1990s, when I was in the Army, and loved it. The newest edition adds the “New” to the title, and is even better. Be forewarned though, most of the people he discusses are very….well….”earthy” would be a good way to describe it…. (Books are the only thing I’ve ever actually bought from Real Goods, strangely. They offer a lot of really cool off-grid stuff…)