Tiny House, Tiny Living, The Tiny Life.

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Tiny House Solar

I know many of you have been wanting this post for a while, but it’s finally here: my solar panel system for my tiny house.  I wanted to get the feel for what it is like to live off the grid so I could share more details with you all about what it’s really like.

Tiny House solar panels

So first, the high level details of my system:

  • 2.25 Kw panels – Nine, 250 watt panels
  • Batteries 740 amp/hr total – Eight, 370 amp/hr 6 volt Trojan L16 flooded lead acid
  • Cost for parts about $10,000 (excluding tax and shipping)
  • Off grid, battery bank, plus 5,550 watt backup generator
  • 24 volt system

Specific Parts:

  • (9) Canadian Solar CS-6p 250 Watt Poly Black Frame  (Spec Sheet)
  • (1) Schneider SW 4024 (Spec Sheet)
  • (1) Schneider MPPT 60 Charge Controller (Spec Sheet)
  • (8) Trojan L-16 6v 370 AH Flooded Lead Acid Batteries (Spec Sheet)
  • (1) Schneider System Control Panel (Spec Sheet)
  • (1) Schneider Interconnect Panel (no spec sheet)
  • (1) Midnight Solar MNPV 80AMP Dinrail Breaker (Spec Sheet)
  • (2) Midnight Solar Surge Protection Device AC/DC (no spec sheet)
  • 50 Amp RV power Inlet (Spec Sheet)

Before anything I needed to determine the best placement for the solar panels to make sure it had good solar exposure and didn’t fall into shadows too much.  To do this I used a tool called a “solar path finder” which is a semi reflective dome that you position at the location, then snap a photo.  The photo is then loaded into a program and spits out a whole bunch of calculations.

Solar Path Finder

Solar Path Finder

So once you upload the image into the software and then trace the treeline outline, you enter in your location, date and time.  It then can calculate how much power you’ll produce based on 30 years of weather patterns for your exact location and tree coverage.

My reading with the pathfinder

My reading with the pathfinder

Then it spit out all the calculations:

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With that in mind I knew what I could expect out of the system I had designed.  It also was a way to verify my assumptions.

Once I verified that the system was going to be well suited to my needs I had to build my panel support racking.  I did this out of pressure treated 4×4’s that were each 10′ long.  These things about about 300 lbs each so I don’t have to worry about wind picking up the panels.  I opted to build them because it was cheaper than some of the turn-key option out there and most of the for purchase ones required me to cement in the ground; I rent my land, so I wanted a mobile solution.  The racking is technically mobile, but not easily so.  If I remember correctly it was about $500 in materials to build this part.

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Next we installed the panels.  This part was pretty quick and the stands worked out perfectly.  The panels are 250 watt Canadian solar panels.  They are wired in groups of three, then paralleled into the system.  To give you a sense of scale, these panels are 3.3 wide and about 4 feet tall.

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Now I know many people want to know why I didn’t mount these on my roof or could they mount them.  You technically can mount on your roof, but honestly the number of panels that you need to practically power your house is too many for the roof.

There is some other major bonuses of being on the ground:

  • Much cooler, roofs are very hot places in the summer and solar panels drop in efficiency when hot
  • I can put my house under deciduous trees, this means in summer I’m in the shade, in winter I get the solar gain
  • Way easier to clean and monitor

Cleaning your panels is pretty important because you loose efficiency as residue (bird poop) builds up.  Also as I learned just a few days ago, when it snows, you need to clear your panels.  Cleaning becomes super simple and a lot safer when you don’t have to climb onto a roof via a ladder.

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Just this week we got a decent snow, 3 inches, which is quite a lot for Charlotte.  The first thing I had to do when I woke up was clear off the panels because with the snow, they made no power.  This was compounded because since it was cold, I needed more heat.  I can’t imagine having to drag the ladder out and try climbing on a icy roof… No Thanks.

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Next I built a cabinet to house all the gear.  I wanted a stand alone space because the batteries are so heavy.  At 118 pound each, plus cabling and other equipment the whole unit is over 1,100 lbs.   The top and bottom sections are divided so that the gasses from the batteries don’t go up into the electrical section and explode.  More on that later.

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The batteries are wired in series parallel.  The batteries are 6 volt each, in series of 4 the create a 24 volt unit, then I have two of these 24 volt units in parallel.  The reason I choose to go 24 volt over a 48 volt (which is more efficient) was because the equipment was a little cheaper, but also it allowed me to select components that I could add more panels and batteries very easily without doing equipment upgrades (just a factor of the abilities of the units I choose).  This way I can add up to 15 panels and a lot more batteries without upgrading the electronics; I can also stack these inverters so if I ever go to a normal sized house, I just add another unit and it just plugs into my current one.

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In this photo going left to right: Din Breaker Panel, Charge Controller, Interconnect w/ control panel, inverter.  In general the power flows in the same manner (but not exactly).

  • Breaker Panel: manages power from solar panels
  • Charge Controller: manages power to batteries etc.
  • Interconnect: a main junction box and breaker, holds control panel interface
  • Inverter: takes power in many forms then outputs to they type of power you need

Once the power goes through the system it outputs to a huge cable that you can see sticking out of the bottom of inverter then goes right.  From there it runs to this:

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This is a 50 amp RV style plug.  The reason I did this was two fold.  City inspectors are less picky when it comes to non-hard wired things.  This setup also lets me roll into any RV campground and hook up seamlessly.

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The plug goes into a 50 amp RV female receptacle.  This is important that you don’t have two male ends to your cord.  This is dubbed by electricians as a “suicide cord” because if you plug in to a power source, you have exposed conductors that are live; accidentally touch them, you complete the circuit and zap!

suicide-cable

You want a female end to your cord so that you reduce the chance of being shocked.  I also turn off my main breaker at the power source when I make this connection, then turn it back on.

SimpleElectricCover

If all these mentions of watts, volts, amps, amp hours etc are making your head spin a little, you may need to go back to the basics.  I have an ebook called Shockingly Simple Electrical For Tiny Houses which guide your through all the basics.  As of now, it doesn’t go too deep into the solar aspects, but the basics of electrical, wiring, power systems and determining your power needs are covered in depth and designed for those who are totally new to the topic.

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So once the power passes through the power inlet it goes to the panel.  Near the bottom you can see the backside of the power inlet, it has a large black cord coming out of it, into the box and ties to the lugs.  From there it goes out to the house.

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Back outside now, looking at the cabinet, on the sides of it, you can see the vents.  When you use lead acid (LA) batteries you have some off gassing as the batteries discharge and recharge.  These gasses are volatile and can ignite, possible leading to an explosion.  So to take care of this I installed two vents like this which provide adequate venting.  As mentioned before my battery section is isolated from the electronics section where a spark could occur.

This off gassing is a concern with Lead Acid Batteries, but other battery technologies don’t have this issue.  I choose LA batteries over AGM (absorbent glass mat) because LA’s have more cycles and cost a bit less.  Lithium Ion at this point is cost prohibitive.  My batteries should get about 4000-5000 cycles (11-14 years) before I need to replace them.  I figure in about 5 years battery technology will have progressed so much I’ll change early.  New batteries will cost me about $4,000 of the LA variety.  IMG_3123

Here is my grounding wire for my system.  This is actually one of two, another is located at the panels them selves.  My house is also grounded to this through the cable hook up and to the trailer itself.  A really important note: ground depends on a lot of things, one of which is if you house electrical panels is bonded or not, if you don’t know what that means, read up on it, its very important.

The other component of this system is the generators.  In the winter months I may need to top off my batteries every now and then, basically when its been really cold and very cloudy for a week or more.  I had a Honda EB2000i already which I really like.  It’s very quite and small.  The one downside to the Honda is that it only does 1600 watts and only 120V and I needed more power and 240V.  So I picked up another generator, a 5500 watt 240 volt Generac for $650.

generac

Here is a video that compares the two generators in terms of size, noise, output and price.

So that’s the surface level details of the system, I’m going to be doing something in the future which will be a how to size, choose parts, hook up and all the other details of doing solar for your tiny house, but that is a longer term project, most likely will take about 6 months to pull together in the way I’d like to do it.

New Zealand Tiny House

In the winter of 2013 Brett Sutherland of Auckland, New Zealand set about to build a tiny house of his own design on a tandem-axle trailer right in the driveway of his parents home. Start to finish took just five months but with a bit of experience and  a lot of tenacity and dedication Sutherland built one of the most unique, space-saving, tiny house trailers visible on the web today.

Mobile Villa 1

Nicknamed the MV (Mobile Villa) by Sutherland himself the inspiration behind the build was really a practical one. As Brett explains to Bryce Langston in a recent interview, “The biggest thing I was trying to avoid was losing all my money as soon as I touched down and that’s what happens when you pay a rent.” Brett truly wanted an off-the-grid, self-contained home that would allow him to concentrate more on his art than making money. He wanted to do more in life than just survive economically.

At 161 sq.ft. the Mobile Villa cost just $10,185.00 USD to build and features a sitting area, a kitchen, an upstairs sleeping loft, and a small bathroom with shower.

MV layout

MVtoilet

The roof line of the MV is a two-tier shed roof which Sutherland admits was done for airflow purposes in the sleeping loft as the top tier features a crank-out, horizontal window. The slope of the roof also allows for generous rain catchment which further allows Sutherlands pursuits for total off-grid living. The lower tier supports Brett’s two solar panels which then further feed into his electric panel situated just above the toilet area and out of direct sight and hosting a 30-amp solar regulator, battery isolator switch, and switchboard.

Upon walking in the tiny house there is immediately a twin-size day bed to the right offering guests a place to lay their head when visiting as well as a couple of sitting chairs directly across the room for more social moments. Another interesting aspect of the house is the use of what looks like standard plywood with a semi-gloss finish rather than the pine tongue-and-groove more frequently seen in tiny houses. This technique has been used before in several inexpensive yet practical ways such as the Zen Cube Mobile Living Space.

MV Living RoomIt’s what is under the day bed that is perhaps the coolest element as it houses the Flexi Tank water storage bag which is connected directly to the downspout of the gutter on the lower roof tier and holds roughly 100 gallons.

MV Water StorageOther features of Sutherlands tiny house are typical of many tiny houses:

  • 12-volt water pump (which services the sink and shower)
  • Propane cook stove
  • 12-volt outlet(s)
  • Sawdust toilet

Since construction on Sutherland’s Mobile Villa ended he has moved it to a friend’s property in Bethells Beach in Auckland. With the ocean as his front yard, no shortage of palm trees as his neighbor, and plenty of room for friends and guests to come and enjoy a barbeque Sutherland and his MV are perfect testimony to the freedom, mobility, and consciousness that tiny living can bring!

MV Moving

Your Turn!

  • Can you see yourself living tiny at the oceanfront?

 

Via

 

Future Of Batteries

With many Tiny Houses wanting to live off the grid, many of us dream of all electric cars charged by green energy sources, we get frustrated when our devices only last a scant few hours.  What does all this have in common?  Batteries.  Technology has allowed us to do so many interesting things in today’s world, but batteries are still from the stone age, or so they seem.  They are inefficient, heave, expensive, and have a low mass/volume to power ratio.  I have said to friends many times, want to make millions, make a better battery.

Living off the grid is one of the biggest benefactors of improvements in batteries.  While solar cells aren’t quite there yet, they have made some big strides in making them cheaper and more efficient.   The point is, they are on there way.  The second component to a solar array is storing that energy to have on had at night or when you are in some heavy  usage.  Better batteries will allow us to do this.  Here is a good article from Good.

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For those who didn’t pay attention in class: Batteries are typically comprised of three main parts: a cathode (positive electrode), an anode (negative electrode), and an electrolyte (an ion-rich liquid that separates the electrodes). The movement of metal ions between the cathode and the anode through the electrolyte (and back) releases electrons, generating electricity

Lead-acid batteries, found in conventional automobiles, have a low ratio of energy to weight, which means it takes a lot of battery to provide just a little juice. Nickel-metal hydride batteries, the ones powering today’s hybrids like the Toyota Prius, are significantly lighter, but offer only a slight improvement in efficiency. Neither can compete with gasoline-fueled internal combustion.

Several technologies are competing to fuel the next generation of EVs. All of them, however, have serious weaknesses that researchers are still attempting to address. “People are betting on different horses at this point in time,” says Matt Keyser, a senior engineer in energy storage systems at the National Renewable Energy Laboratory in Golden, Colorado. “Which one is going to come out and win is anyone’s guess.”

Here’s a look at some of the technologies vying to corner the EV market:

Lithium-Ion

lithium-ion-smallThese batteries use lithium ions as the electrolyte. A battery pack made of these cells, while more powerful than lead-acid and nickel-metal hydride batteries, is still 10 times weaker than an internal combustion engine of the same weight. Versions of these batteries are already used in in both the Tesla Roadster and Chevy Volt, as well as many electronic devices, such as laptops and cell phones. The knock on current lithium ion technology: It dispenses its stored energy slowly, so acceleration may be slow, and the batteries take several hours to charge. Also, while lithium is plentiful, it’s not extensively mined, so it’s expensive to obtain. It may take up to 10 years for supply to catch up to projected demand.

Ultracapacitors

ultracapacitor-smallUltracapacitors charge quickly and dispense their charge speedily (curing the slow acceleration problem that plagues some electric cars). They also last much longer than batteries—they can be recharged over and over again, whereas batteries eventually will not recharge. That’s because ultracapacitors use electric fields, instead of slowly depleting chemicals, to get charges. They are already in use in short-run electric buses in Russia and garbage trucks in the United States. The downside: They only hold their charge for a limited time, so it’s unlikely that ultracapacitors will become a viable option for powering a car alone. “I think ultracapacitors are a technology that’s going to work with [battery] systems,” says Savinell. However, one Texas-based company called EEStor says it has solved the storage problem, claiming its ultracapacitors will enable a small car to travel 250 miles on a single charge that only takes five minutes to complete.

Fuel Cells

hydrogen-fuel-cell-2-smallLike batteries, fuel cells have cathodes and anodes and involve a chemical reaction, specifically making water and electrons (and thus electricity) by combining hydrogen with oxygen. The technology is simple enough, but the safety issues are the drag: The transport and onboard storage of highly explosive (remember the Hindenburg?) hydrogen gas could keep fuel cells from catching on. In addition, the catalysts needed to split hydrogen atoms into protons and electrons (like platinum, palladium, rhodium, nickel) are very expensive. “Fuel cells from a mobile standpoint are difficult,” says NREL’s Keyser. “Maybe in twenty five or thirty years down the road, we may be able to deal with all the storage issues, the transport issues, the infrastructure issues, the catalyst itself.” Seemingly agreeing with Keyser’s skepticism is the Obama administration, which cut $100 million from the federal hydrogen fuel cell program in 2009.

Redox Flow

vanadium-redox-flow-smallSimilar to fuel cells, redox flow batteries would require filling stations rather than plug-in capability. In this case, a charged electrolyte flows through the battery, producing electrons. After a while, the electrolyte loses its charge and needs to be pumped out and replaced. The electrolyte is typically made with vanadium, which is the 22nd most abundant element in the world. It’s also very safe. “If you were to spill this on the road and light a cigarette near it, it’s not going to go off like hydrogen,” says Keyser. “The big thing with [redox flow batteries] is: Are you going to get the energy density or power density that you need for the car itself?” Right now, even lithium ion cells are several times more powerful than redox flow cells. German researchers, however, claim they have a method to increase the distance redox flow batteries can power a car by four to five times, rendering them roughly equal to lithium ion batteries.

Metal Air

metal-air-battery-smallSavinell and Keyser both point to metal air batteries as the technology of the future. This battery uses the oxygen in the air as its cathode, which means it doesn’t need as much material and gets more energy for its weight. Depending on what material is used for the anode, metal air batteries could be anywhere from three times more powerful than lithium ion batteries of the same weight to as powerful as an internal combustion engine. IBM intends to bring these to market in five years for smaller electronics. “For lithium air, I think that’s more ten to fifteen years down the road [to power a car],” says Keyser. “We’re just starting to really look at that and understand all the benefits and the costs associated with lithium air batteries.” One major barrier remains: When the oxygen reacts with the electrolyte to form ions, it also creates a solid that can gunk up the air intake, blocking the battery’s function. Researchers are searching for an electrolyte that will produce the necessary ions but avoid the formation of this solid.