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If you have been following us, you know that our desire has always been to go off-grid with our Tiny.  Having the ability to park our Tiny anywhere and not be dependent on a power cord, would be a great achievement.  That would entail some solar panels, an inverter, a charge controller, and some batteries.  How difficult could this be?  Lots of people seemed to have done it before.  Well, once again, our situation was a bit unique so it required a fair amount of research and custom set up. There was lots to be learned.

There is some information on the internet about being off-grid with solar, but we highly recommend finding someone you trust as an advisor.  For us, that was Liam O’Brien, “the genius”, who you will hear more about during part two of this post.  He can best be reached at Kilawatt Consulting.

First of all, when considering an off-grid system, one has to look at the power requirements; the loads one is putting on the system.   Most tiny home off-grid systems are 110v.   With our kitchen set-up, we really wanted to have an oven (actually a steam-oven), so we need a 220v system.  We also learned that the heat pump/ac system works most efficiently on 220v.   Using some template spreadsheets, we then added all the other components and their expected draw so we could arrive at an appropriate system size requirement.

Our roof design, with a deck and access window, limited us to six solar panels. Good news is that we could divide them into two strings of three.  It’s important to keep the system in balance.  Given the panels are about 300 watts each, that would give us a 1.8kW capable system.

On the battery side, most people get regular 12v lead-acid batteries.  These are similar to the ones in your car.   However, we had two concerns with this approach.  Lead-acid batteries are not what they call deep-cycle.  This means, unlike your cell phone battery, you can’t run them down close to zero before you charge them again.  Ideally, they should be 50-60% most of the time.  So with a 10kWh battery capacity, you would really only have 4kWh of use.  Second, lead acid batteries are HEAVY and take up space.  Weight and space, not friends of the Tiny.

We quickly realized that lithium-ion batteries is what we wanted and needed.  There are a few options available for home systems, but they are most often dependent on being connected to the grid and quite expensive.   A Tesla PowerWall appeared to be a great choice but this was not that straight forward.  They had the greatest capacity, but did not offer an off-grid option.  Even after we became part of their “off-grid” beta test program, they quickly shut us off once we told them it was for a tiny house on wheels, e.g. movable.

We were not going to give up.  Additional research uncovered that there was a whole business out there of people tearing down Tesla cars and reselling the battery packs.  So now we had to figure out how to connect these to a solar power system.   Not trivial.   But it all started to make sense.  We were going to build our own PowerWall.  Each of the Tesla packs (there are 16 of these in a Model S) are 24v, about 5kWh, providing about 235Ah.  They weigh about 55 lbs (25 kg).  We figured we could use 4 of them.  Connecting two in series would give us 48v and then we would connect two in parallel to give us a total of 24kWh capacity.  Above is a sketch of what the that would look like. 

After contacting various solar integrators on the internet, we narrowed down our configurations of components to a MPPT Charge Controller from Midnite Solar and a 48v inverter from Magnum.  The MPPT is the most efficient way to convert solar panel output to battery charge and a 48v inverter takes the DC current from the batteries and converts it to AC power which goes into our electrical panel.   Two tasks remained.  We had to figure out how to put all the components together and get all this at the best price.  However, we were mostly concerned about hooking up the Tesla batteries since we chose the nonconventional route.

We continued to search the all mighty U of I (University of the Internet) to find articles, examples, or perhaps some youtube videos.  Luckily, we came across one from DIY Homestead.  They had essentially done what we wanted to do.  We contacted them for some more details,  and found the one and only, Liam O’Brien.  He is a wealth of information, practical, great work ethic, and a super, awesome guy.  In short, he is the subject matter expert in off-grid solar.  Simply put “the genius”.  He not only helped us source the right gear at a lower cost, he also offered to come down and help us install.  Turns out he only lives a few hours away.  Part two – the install – will be posted in a few days.

Here is the link to part 2

If you followed us along thus far, you come to know that even though this is a tiny house, there is so much detail, so many choices, and so many decisions to be made. The roof is no exception.

From the research we did, almost everyone goes for a metal roof. Especially for those houses that will frequently be on the move. It does make a lot of sense as metal roofs are fairly light weight, virtually maintenance free, and hold up extremely well under windy conditions. Going down the road at 70 mph (120 km/h) is equivalent to being in a hurricane, so better be ready.

Once the material selection was made, we now had to make a decision on the style. Again, research told us that a standing seam was the best choice as we were going to have solar panels mounted. It turns out that there are specific mounting brackets that fit right on the seam, allowing us to mount them close to the surface and without penetrating the actual roof.

Next was the color. At first we thought a dark color, even black, would go best with our overall design and color choices for the siding. However, it turns out that a dark surface may not be the best option underneath solar panels. As black attracts heat, it would make our roof top deck unbearably hot on those days when we would enjoy being up there. So given that, we selected a light gray color, which turned out great.

We had done some roofing projects in the past, building a couple of small sheds using regular shingles. We also found several DYI Tiny home builders that installed their own. Nevertheless, when considering the tools needed to properly install it (especially to bend metal sheets around corners) and the implications of not properly flashing seams, we decided to outsource this and hire a professional.

Global Home Improvement sent over a great crew of four who spent two full days on site. Can’t imagine how long it would have taken Julia and I to do this.

It really was a custom job, starting with the fabrication of the actual panels. In this video here, you can see how they extruded complete panels from a roll of metal, right in our driveway. Fascinating!

We had to mount our furring strips and trim board as guides, so that the drip edge could be properly installed. We also had to make the holes and prepare for the kitchen exhaust vent, wood burning stove vent pipe, and the roof top access window. These three items, especially the window, made this project quite complex. The rest was really just three rectangles with a very low slope.

For our kitchen (and we have a lot more exciting news to share about that soon), we decided to go with a Wolf external blower for the fan. This way we could both have powerful fan to exhaust any fumes, but it would also limit the noise it made. To say it is a substantial unit, especially for a tiny, is an understatement. But it fit like a glove and the crew made sure it was mounted and sealed properly.

Our Tiny Wood Stove came with a roof vent kit. We have not installed the actual stove yet, but needed to get the pipe measured, aligned, and integrated into the roof. The double wall piping requires a 2″ space to combustibles, so we had created a square box in the ceiling prior to the insulation going in. Now we just had to cut the hole, mount the bracket that came with the kit, and make sure it was all the right height. The roofing crew once again got it all incorporated into the roof design and made sure it was properly sealed.

Lastly was the Velux Roof top access window. This was integral to our design as it was the way to the roof top deck. If you recall, our floating stairway was the entrance ramp. As with all the other regular windows, we had Volstrukt frame this opening as well. Because of the low profile of our roof and our desire to increase the angle of the window, the crew had to customize the flashing. Again, so grateful we had these professionals on site as it would have been a difficult task, to say the least.

We are super happy with the results. The light color, along with the insulation, kept the tiny house nice and cool, even during a few days of close to 90 degree F (30+ Celsius) weather. Now we are ready for the solar system which we are installing next week.

Planning

As we are leading up to the day of our insulation install (Closed Cell Foam), we had to ensure that all the electrical and any in wall plumbing was completed.  We honestly did not think that it was going to be that big of a deal.  A few lights here and there, some plugs, the appliances….   well, 500+ feet of regular wire and 500 feet of low voltage wire later, and we have one wired house.  And actually, this is just the rough in.

We started off to make a plan of where we wanted electrical plugs and switches. We then checked all the appliances and other electronic components to understand their draw and circuit requirement.  Lastly,  we drew a plan for all the lights and what we wanted controlled by our automation system.  You can see these sketches here.

The way the automation system works is that all the switches are on regular 110v and all the lights are on low voltage.  When you turn on a switch, the signal goes back to the main controller.  The controller then sends a signal to that light (or group of lights) using low voltage.   This means that every single light or group of lights you want to turn off or on, needs to have a direct feed.   It also turns out that most of the appliances suggested a dedicated electrical circuit, which meant they needed a separate wire going back to the panel.   We may have overdone it, but better safe than sorry, so we erred on the conservative side when faced with an option.

Beyond the obvious

Our water pump needs 12volt as does the fan for the compost toilet.  We are hoping to install a Orbital Shower of the Future in the fall, so it needed to be wired as well.

Because tiny houses are so well insulated with little to no air escaping, we also have to handle the natural condensation that happens.  So we installed a Lunos ductless, simple, and highly efficient heat recovery ventilation (HRV) system.  It required thermostat wiring between the main switch and each unit (one in each end of the house).   Here are a couple of pictures.

Lastly were a few speakers for the exterior which were easily wired.  We will then simply mount and connect them once we park at each destination.

Plumbing

Now for the plumbing, it was significantly simpler.  We used PEX because it is very easy and fairly fool proof to install.  (you see some of it in the main picture above) It uses red and blue tubing and a simple ring that you clamp around the connectors using a special tool.  We only had the bathroom sink, washer, pot filler, and outdoor shower to connect.  The rest is all accessible after the insulation goes in.  I will do another post on the actual plumbing with the tanks, pumps, filters, etc.  That is a whole science in itself.

 

 

 

So there you have it – electrical and plumbing all ready for the insulation to go in….  (postponed again for a week due to colder weather)

A few more pictures for you

While every task and activity around building a house, even a tiny one, is a big deal, it is not every week that we see huge changes.  So this past week we sweated the small stuff – worked a lot on paperwork and research,  ran our utilities, and built the framing around the wheelwell.

There are still many decisions to be made and products to select.  Lucky for us there have been so many before us and many like us, who post their choices and reasons why.  A major next item for us is the automation system, so let us know any insights you may have.  We are also having to select our standing seam metal roof vendor.  Any recommendations or suggestions are welcomed.

We have started to receive some of our other items so we will post our thoughts and selections as we install them.  One small set back this week was our roof access window. We were all excited about installing it and found it cracked when we opened the box.  A replacement should arrive in the next couple of weeks.

As we have mentioned on our earlier posts, we will primarily be on the road with our tiny home.  However, when we are home, it will be our guest house.  We knew we needed water and electricity brought out to the tiny house (it is not always sunny enough in NJ for us to rely on solar power 100% of the time), so we had laid some piping under our parking spot.  With the deep freeze, at least temporarily over, we took the opportunity to dig the rest of the way and draw the power cable and water line.   For the water, we decide to get heated drinking water hoses and run them through 2″ (5 cm) piping.  Because we have about 80′ (24.3 m) of ground to cover, we had to get two 50′ (15.24 m) hoses, each with their electrical connection at the end.

Thinking ahead,  we may want the ability to rent the space and have other tiny homes be able to park on the property.  That being the case, we went with a 50Amp 220/240v electrical line with an electric meter.  We had some help with the digging, but it still took us all day.  We are pretty happy with the results, though.

 

 

Going back inside the tiny house, we focused on the wheel-wells.  The framing sits on top of them, but they protrude further in and is just a thin layer of steel.We heard from several tiny home owners that this area is often the source of drafts and cold.  Since we are having blown in closed cell foam insulation installed, we decided to build a thin frame which would allow for 2″ (5 cm) of insulation.  Yes the walls are thicker than that, but we needed to 

minimize the depth as we have appliances that will back up right to them.  We built both frames but installed one of them thus far.

 

till next time….

What a difference it makes to put in some windows.  Great progress over the last few days.  See the video below.

http://tinylivinglivinglarge.com/wp-content/uploads/2018/01/large.mov

http://tinylivinglivinglarge.com/wp-content/uploads/2018/01/720p.mov