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Building a Little Solar-powered House on the Prairie: Off-the-grid or Grid-tied?

Dan Thiede
June 06, 2012  |  19 Comments

View of the house from the prairie

A year ago, Mike Larsen and Linda Nelson left their beloved urban Minneapolis home and moved to the prairie in southeast Minnesota near Altura to live in a way more connected to the land. In this story, Mike writes about how they came to the decision to build their off-the-grid home.

Off-grid or not off-grid—that is the question. Indeed, that was a HUGE question Locus architect Paul Neseth posed to Linda and I as we sat down to yet another design session. Like “paper or plastic,” but a lot lot harder.

We’d still be designing if not for our one guiding principle, the principle by which all our design decisions were judged. Though on paper, our house was turning out to be “green, sustainable, earth-hugged, solar powered, masonry heated, humanure composting, rainwater harvesting,” we never told Paul that’s what we wanted. Instead, we asked Paul to design us a house that does one thing for us—enables the Connection.

The Connection

First, connect us to the Land, our 62 beloved ridge-top acres overlooking Whitewater State Park. Second, connect us to our friends, family, neighbors and community. Third—if we dare admit such a wild proclivity—connect us to the Divine, the great mystery that flows through and binds all of these. That’s it Paul, just this little Connection; can you do that for us? Can any house do that for us? It is, after all, just a house.

Now, one month after moving into the house, it’s too early to say we did it. But, thanks to Paul, at least we attempted it, one decision at a time. And no decision was tougher than off-grid versus grid-tie (or not off-grid).

Grid-tied versus Off-the-grid

There was never any debate about solar electric. After all, what could connect us more to the Land than harvesting sunlight to produce electricity, not unlike the Indian grass on our 40 acres of newly planted prairie. The only debate was storage. Where do we store excess electricity so we can still “plug-in” when the sun isn’t shining?

The house during constructionThere are definitely upsides to a grid-tied home—and we almost went that direction. By storing excess electricity on the grid, a grid-tied system would directly connect us to our neighbors and community. We’d become one of their electricity suppliers, potentially (and perhaps sneakily) reducing their reliance on fossil-fuel generated power. We’d also earn income by selling power to the electric company, hopefully offsetting the cost of power we purchased from the grid when the sun isn’t shining. And lower total cost means less hours employed means more time on the Land.

But for many reasons, we decided to go off the grid. Our first (and most valuable) step in going off-grid was touring four homes. By generously opening their off-grid homes to us, these pioneers gave us our first big “Aha!” There are as many good ways to go off-grid as there are good reasons to do it. And beyond all the good reasons for a grid-tied system, we discovered what draws some to off-grid. We knew about independence and self-reliance. But tinkerer? One guy had so much excess electricity that he not only drove an electric tractor, but he gutted a Jaguar to build his own electric car. Another recovered methane from cows to power his generator.

While we saw (and found online) much useful how-to information on batteries (for storing the electricity), charge controllers (for charging the batteries) and backup generators (for when the batteries get low), we didn’t anticipate the big problem—lack of local off-grid solar installers. Many installers do grid-tie. But few, we painfully discovered, have experience installing off-grid electric.

Powered by the Sun

Solar PV powers the entire houseSo when we hired Curt Shellum of Solar Connection, we knew (because he was so forthcoming) we were buying his grid-tie skills and hoping that he’d close the gap to off-grid. And he did: He installed 12 ground-mount photovoltaic panels producing 2.9kW max, 16 batteries designed to store 4 days of typical electricity usage, 1 invertor for charging batteries (from solar panels or generator), inverting battery DC to usable AC and displaying performance (red means I better start the generator) and 1 generator (powered by our tractor’s PTO).

And the results never cease to amaze me. Since coming on line, our off-grid system has powered the remainder of the construction project: 3 inch drills, miter saw and attached vacuum, and fans blowing all night to dry the sheetrock mud. And now that we’ve moved into our home, the system has done all we need powering lights, 5 pumps, 2 fridges, freezer, computer, and phone. I was so relieved when I heard the roaring whir of the Vita-mix blender as it turned frozen strawberries into summer-tasting smoothies. Only once in 4 months, fearing the battery charge level would drop below the 50% spec. limit, did I start the backup generator. And it turned out I didn’t need to—the next day was plenty sunny.

The Off-grid Journey

And what of our highest value—the ultimate purpose for our house—the Connection? Today is the seventh consecutive day of low-slung clouds and gully-ripping rain. The batteries remain 82% charged. At 11am the solar panels are producing zero watts of electricity. Nothing. So I feel a little anxious. Will my batteries get overly-depleted? Will I need to hook up the generator? And this slight anxiety—or better put: this heightened awareness of real solar energy—connects me to the Land in a way I never knew possible. I feel perhaps like the summer-loving Indian grass. “Where’s the sun?” And when, indeed, the sun’s rays finally strike the PV, replenishing the batteries, powering our house and our lives, I too feel replenished.

Indigo blooming outside the houseI need to make a confession about our brief grid-tie experience. The moment we started exploring grid-tie, we started designing our house differently, to suck more juice. Bigger fridge? Why not? The grid is always there. The moment we went back to the off-grid, the big fridge disappeared. So did any light that is not LED. Off-grid drove a behavior change for us that grid-tie never induced. And I liked the change.

Unlike the steady, always-as-much-as-we-want grid-tied system, off-grid follows the cycle of abundance and scarcity. This cycle connects me to the Land because it’s how I’m coming to perceive the Land: life, death and life-renewed. Lately, as I watch the dance of the wind-whipped grass, I’ve even thought of adding a small wind turbine. Yes, it will help keep the batteries full. Better yet, perhaps I’ll learn to feel more thrilled as the wind stings my face. Who knows what we’ll do? Off-grid isn’t a destination. Off-grid is a journey.

What do you think about grid-tied versus off-the grid homes? Let us know in the comments!

You can follow all of Mike and Linda’s adventures in sustainable living and the house the land built at Mike’s blog, Rah-dur. This was originally posted on the MN Energy Stories blog from the Clean Energy Resource Teams.


The information and views expressed in this blog post are solely those of the author and not necessarily those of RenewableEnergyWorld.com or the companies that advertise on this Web site and other publications. This blog was posted directly by the author and was not reviewed for accuracy, spelling or grammar.

19 Comments

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John DAngelo
John DAngelo
June 8, 2012
Marvin, What I said was not "more is bettered" but "more PV is better". If your sister paid over $100,000 for an off grid system then I think she must have installed it some time ago when PV models where much more expensive and or she had to have such a large array because her loads dictated that size. Typically, from my 40 years in the off grid market, the array sizes for an off grid house is between 2 and 6 Kw in size. There are two main ways for "back up" power for off girders. 1. Back up generator - the most often used 2. adding a complementary RE system to your main system. The least expensive is usually the back up generator that charges through one's off grid inverter. The later is called a hybrid system. However, that system can still need a back up generator depending on the loads of the individual home. I propose a third. Adding more PV modules because they are so inexpensive now, require no fuel and create no noise. The added benefit is your battery bank will perform better, last longer and when you have some sunny days, take that excess and charge up an electric car! The cost today of just PV modules is between $1.20 and 1.50 a watt. The cost of PV has NEVER been so inexpensive as it has today. As Mike pointed out he was surprised at how much power his PV array produces even on cloud days. Larger PV array, more power on cloudy days and may can get to the point where one may sell the back up generator. To me one can never have two big of a PV array. One will ALWAYS be able to find a use for FREE electricity. I believe excess electricity from over seized PV arrays will go ti charging EV's than to any other use. AFter all we have to get beyond gasoline. NOTHING can compete price wise as the energy being produced from a PV array that has been bough and paid for.
Marvin Hamon, P.E.
Marvin Hamon, P.E.
June 8, 2012
The problem with the more is better idea John is that more is expensive. My sister has an 11kW off-grid system that cost over $100k installed, and that was a good $/W deal. She still has to run a generator sometimes. Not many have the extra cash to go that route. Most people can't reasonably do more than 95% uptime with only solar and that's about 18 days a year without power. A generator is really the only way to go to pick up those days at a reasonable cost. The cost to shave days off the last 18 with solar increase exponentially with every day. Plus you end up with a PV array that over produces energy 95% of the time and that is wasteful too. Of course you can always just plan for a power outage. It's not like we can't breath without power. As long as you have a good system for keeping frozen things frozen and cold things cold a few days without power during the year might just break up the routine.
Mike Larsen
Mike Larsen
June 8, 2012
Cloudy days – PV is very, very impressive. If it ain't raining, it's producing, at least since we moved in on March 17. Its cloudy day performance is much better than I expected (and much better than our solar hot water). We'll see if I'm still singing that tune come the grey days of November. Still I agree with the PV advantage over wind. Not to lose sight of what I call the Connection, my appetite for wind energy is merely to like the wind more. What I've noticed is that PV makes me like sun more. Rainwater harvest makes me like rain more. Wood heating makes me like our weedy boxelder trees more. But I haven't learned to like the wind yet. We've got plenty of it up here on our prairie ridge.
John DAngelo
John DAngelo
June 8, 2012
" So awful that we're already contemplating designing out the generator by adding wind (or something). To us, believe it or not, that's fun! It engages us in the creative process of finding solutions." I would simply add more PV modules as they are your best bet. No moving parts, no noise, 25 year warranty output. Wind 5 year warranty and noise. My advice to off grid people is oversize the heck out of your PV array. When you get that all electric vehicle in the future you will be able to provide all of your "fuel" for free if you have a large enough array. The larger array one has the more energy it will have on this dark cloudy days. I am sure you have noticed by now that even on cloudy days your PV modules produce electricity. We have a 5 kW array and even on the worse days it will still produce about 1 kW peak. So really there is this myth that PV arrays do nothing on cloudy days. Not true. Another factor is that PV modules are at there lowest in history and they won't be going much lower as I see it. One can never go wrong with either to much money or to much electricity. I for one sure feel better having to much electricity than not enough.
Mike Larsen
Mike Larsen
June 8, 2012
I'm so appreciate of all this knowledge you're sharing and humbled as well. I just told my wife, "Next to these commenters, I feel a little inadequate. We just did it and told our story." She replied, "Maybe that's the point. You don't have to be a guru to do this! You just have to want to."
John DAngelo
John DAngelo
June 8, 2012
To Mike-larson "The moment we went back to the off-grid, the big fridge disappeared. So did any light that is not LED. Off-grid drove a behavior change for us that grid-tie never induced. And I liked the change.' I think what you wrote here is the key difference from being on grid and off grid. Being on grid one really has an infinite back up - the utility company. Being off grid forces your hand at facing a new reality. Living with a finite energy source. Yes RE systems collect FREE energy , but what becomes evident immediately is that the lower your energy USAGE (i.e.. Loads) the less expensive the RE system that collects the energy one NEEDS on a daily basis. "We expect to replace the off-grid batteries every 5 to 7 years. Ouch!" The weakest link in your off did system is the battery bank. You say you anticipate replacing your battery pack every 6-7 years and that is about right using a medium quality lead acid battery bank - Rolls, Surrette, L16;s - but it does NOT have to be that way at all. The nickel iron battery and lithium ion are the real answers to the of grid battery issue. It is true that some original nickel iron cells are still being used in home power systems after 80 years of fail usage and that is NOT a false statement. Yes, you read that correctly - 80 years! It is a shame that the of grid industry today still uses lead acid battery technology when a far superior battery for home power systems exists on the market today, The other battery technology that may even be better than nickel iron technology is the lithium ion battery. However, that battery technology is about twice as expensive as nickel iron, but the advantage is being able to take a really fast charge. Just imagine getting 2 or 3 times the energy out of your PV array using lithium ion batteries. I believe by the time you are ready to change out your battery bank you will NOT being replacing it with a lead acid battery.
Bob Condon
Bob Condon
June 8, 2012
Good article, well thought out and it presents a total picture of the considerations that go into the off-grid decision. You don't have to be a "tree hugging, whale saving yuppie" to build a home and make use of the sun to save energy costs and benefit the environment. I live in San Diego California, where we experience ever climbing utility costs, which are probably the higest in the Nation. Clearly going off the grid, requires a comprehensive solution, we are very fortunate that advances in PV, batteries, inverters, and electronically controled switchgear are making such decisions possible. I am uncertain if I will live long enough to see companies offer "package solutions" that enable the homeowner options that will enable the homeowner to go off the grid in almost a "ho-hum" / "everybody's doing it" manner. That day will arrive, it will just take awhile. American Industry needs to look at such potential, as a core development which we can lead the world. Much like we did in Auto Manufacturing, Steel Mills, Shipbuilding, Oil exploration and Mining. All of which have gone by as time passed. We cannot look to the US Government to subsidize this effort, it will take private investors to step in and make it happen. This brief article is a glowing template that can be applied on almost any scale.
ANONYMOUS
June 8, 2012
I've never seen a VAWT that's able to outperform a standard horizontal-axis turbine, so I'd be skeptical of the Windspire claims and would want to see a calculation of the cost of power at my location. VAWTs may be able to handle turbulent winds better, but regardless of the turbine design, you should mount it on a tall tower to maximize energy production. Tall towers will typically put you above the turbulent flow, too, so that concern goes away.
Randall Smith
Randall Smith
June 8, 2012
I honestly don't know. Talk to your solar installer about it. I think the turbines themselves are very reasonable considering the output.
Mike Larsen
Mike Larsen
June 8, 2012
Wind! - Wow, that windspire looks like a promising Vertical Axis With wind, we're very concerned with all the noise and possible impact on our many birds. If I'm ever in Omaha I'll need to go see. Any idea what a small residential installation might cost?
Randall Smith
Randall Smith
June 8, 2012
PS: These are looking like a viable solution to low wind and turbulence problems encountered with horizontal axis turbines: http://www.windspireenergy.com/ Creighton University has them in use on their campus here in Omaha: http://www.creighton.edu/green/
Randall Smith
Randall Smith
June 8, 2012
Mike, adding wind makes sense, but only if you have a reliable source. I would never completely eliminate a fuel-fired backup generator. The PTO is better than nothing, and romantically gritty, but if you have any kind of illness, injury, or pv/inverter system failure in an emergency setting, you could still have power available for lights, water pumping, and refrigeration with an auto-start generator. I presume you have propane available for cooking (and possibly backup heat), so a propane genset wouldn't be a huge leap. Redundant systems are your friend in need.
Mike Larsen
Mike Larsen
June 8, 2012
PV Angle – The angle of our ground mount PV array was set for the dead of Minnesota winter. Though we could change it whenever we want, we haven't needed to. Since spring began, the batteries haven't dropped below 70% and typically get back to 100% every day. Undoubtedly if we were grid-tied, I'd be changing the angle to get more power to sell back to the grid. We haven't lived through a winter yet. That will be another journey I'm sure.
Mike Larsen
Mike Larsen
June 8, 2012
Generator – OK, now you're going to find out how truly "crazy" we are. We actually wanted the generator to be painful. One of our key design principles is transparency: how well can we see a problem. Since we view non-renewable energy usage as a problem, we didn't want to hide it in any way. So yes, hooking up the generator to the PTO, starting the tractor, listening to the horrible whine, all in freezing cold of Minnesota winter, its all quite awful. So awful that we're already contemplating designing out the generator by adding wind (or something). To us, believe it or not, that's fun! It engages us in the creative process of finding solutions.
Mike Larsen
Mike Larsen
June 8, 2012
Cost: Marvin – Cost is VERY important to us in terms of enabling the Connection. Lower cost = less time working for $ = more time on the Land. Cost is complex. Total off-grid installed cost = $33K US ( $24K US after tax credits). We never obtained a firm grid-tie bid, but the installed cost would definitely be cheaper. No batteries ($8K). No generator ($4K). Simpler invertor ($1K). Even considering that grid-tie has the additional installed cost of hookup up to the grid ($5K), it would cost $8K less. But there are hidden costs. Off-grid necessitates super-high energy efficiency: LED lighting, Sundanzer fridge and freezer, Sunfrost fridge. Very expensive. Because of the high power to run a 200 meter deep well pump, off-grid also drove us to eliminate the well and collect rainwater in a cistern, saving $25K!!!! And then there's long term cost. We expect to replace the off-grid batteries every 5 to 7 years. Ouch! Yet the uncertainty around future grid-tie cost frightened us even more. I've probably confused more than helped. You could write a book on this subject.
Randall Smith
Randall Smith
June 8, 2012
It looks like your off grid system choice was ultimately the best, given the apparent remote location indicated in your photos. I was involved in the installation of several off grid systems in Southern California, and by and large the clients were very satisfied. When you get the chance, I would add in a propane fired backup generator with an autostart feature. A PTO driven generator sounds like a lot of work! Also...why the extreme angle on the solar arrays? Are they adjusted for winter sun or is this the fixed angle? If so, you're missing out on quite a bit of summer efficiency. 30 degrees is a good all around fixed angle, and might catch a little more snow, but those arrays look small enough to be able to clear easily.
John Sheppard
John Sheppard
June 8, 2012
Living in the Isle of Man and having been involved in sustainable construction and lifestyle for many years I think the greatest lesson to be learned from Mike and Linda's excellent project is as they discovered certain unpleasant realities of the world in which we live. The majority of us have grown up with a belief that all the necessities of life can be accessed at the push of a switch, house prices will always rise as will our wages. The reality of the fragility of that belief is now being felt by most of us as each year exposes just how insecure the foundation of those beliefs really is. What is also clear is that we can all make a difference by examining our lifestyles and make them more sustainable by quite simple changes in the way we think and the way we use the not so abundant resources that we once took for granted. With the ever rising world population unless we can all acquire a more sustainable outlook the future will I suspect be worse than we can possibly imagine. John
Michael B Casey
Michael B Casey
June 7, 2012
Good article! I live in central New Mexico and never considered grid tie because I envisioned being completely independent of the utility companies. My system was originally undersized. Not enough panels for the household loads. This was the result of insufficient communications between myself and my solar electrician. I've since increased the number of panels. It is important that the electrician knows what the electical requirements of the homeowners will be and size the system accordingly. A propane backup generator controlled by the charge controller to kick on when necessary, say 60% battery capacity, would alleviate the need to hook up a PTO generator to a tractor. Simple, cheap and probably would hardly ever run except in exercise mode once a week for 15 minutes. You've got me thinking of increasing my battery capacity. I have eight 840 watt Rolls connected series parallel for 24vdc @ 1680W. I can only make it through 1 cloudy day. A wind turbine is definately in my systems future as soon as I can find one that is quiet. Don't want my serenity disturbed by prop noise and flutter. Probably will get a VAWT. They are much quieter and designs are improving.
Marvin Hamon, P.E.
Marvin Hamon, P.E.
June 7, 2012
Nice article. One big thing you left out of your grid-tied vs. off-grid decision making process were the costs involved in one system verses the other. Maybe this did not factor into your decision but it might in others so would have been nice to have been included in the write up.

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Dan Thiede

Dan Thiede

Dan Thiede is the Communications Coordinator with Clean Energy Resource Teams (CERTs) at the University of Minnesota’s Regional Sustainable Development Partnerships and Extension. Dan is the editor of the MN Energy Stories blog and manages...
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