Month: May 2018

After a lot of research on the solar equipment and parts, (see this link for part 1 of this post), it was time to order materials.  The list was quite lengthy and comprehensive.  Some of the off-grid solar resources, on the net, offered complete systems, but you do pay extra for their pre-assembled units.  Additionally, you still need a ton of wire, clamps, conduits, etc. when it comes to the actual install. The whole process of determining the required components and which brand was better than the next was quite daunting.  We reached out to Liam O’Brien.  We can’t begin to tell you how helpful Liam was in helping us through this process.  Not only did we save on cost, we also felt confident in Liam’s recommendations regarding the purchase of the best  equipment and parts.  We were so appreciative of Liam’s help that we decided to hire him to come help us with the actual install.

Over the next couple of weeks, a pallet of batteries, boxes of inverters, controllers, screws, bolts, and wires started to appear.  The panels themselves were shipped to the local trucking depot, so I took the old trusty Suburban and picked them up.

The install date arrived and in order to make it as efficient as possible, we had agreed to have Liam stay with us for a few days.  Weather forecast – rain off and on every day.

After his arrival, we took a tour of the Tiny, scoped out the space, took inventory of all the materials we received, and did a preliminary layout of how the panels would be placed on the roof.  We knew there would be three panels on each of the two side roof sections that had to be aligned to the standing seams on the roof.  It was important to maximize the positioning of the panels and be able to securely clamp them down so that they would not fly off the roof when driving down the road.  All the attachments had to be fastened with special clamps so that the roof would not be compromised.  No screws, nails, or bolts were allowed to penetrate the roof.  We also discussed how the cabling would be run, where we would put the combiner box, and how the power lines would run down to the system.

Next was a run to Home Depot. Based on our assessment, we made a list of the additional components required, such as conduits, brackets, breakers, the power panel, etc.   It was starting to get really exciting.  Since it was raining, we spent the rest of the day assembling the inverter and charge controller. We also built the skeleton for the combiner box and realized that a platform needed to be built so that we could mount it on the roof.  What is a combiner box?  It simply takes the feed from one array of solar panels (we have two strings of three panels), combines it with all other strings, and outputs that into one feed that goes down to the charge controller.

We caught some sun the next morning so we decided to do the solar panel installation.  It went smooth and we were really pleased with how it aligned.  As you can see from the pictures, we do have some available space left, but not enough to have a balanced set of extra panels on each side.  We also could not go wide because there are width restrictions and we could not be too close to the ends since that would raise our roof height.  Our design of the house approaches the limits of both height and width (13.5′ [4.1m] and 8.5′ [2.6m] respectively) so we could not go beyond the already set dimensions.

The space for all the electrical, our utility closet, is like everything else, tiny. We have tried to use every available nook and cranny, so all the electrical components, the solar system including batteries, and our home automation unit, all must fit under the stairs to the gooseneck.   We started to place some of the boxes, aligning them with the wires for lights, switches, and outlets, in the utility closet.  A little planning and patience proved to go a long way; we came up with a really neat installation plan.  Liam is also very particular, organized, and resourceful, which came in very handy.

It was amazing to think that we could actually fill up an entire power panel with breakers. There were no short-cuts.  We did everything by the book. We learned a lot from Liam on the do’s and don’ts of wiring.  We wired the house (see our post of the rough-in) using a ton of electrical wiring.  For example, using the right gauge for the size breaker the load required (14 gauge for 15amp, 12 gauge for 20amp, etc.); regular 110v outlets require 3 wires – hot, neutral, ground; 220v has four – 2 hot, neutral, and ground.  In some instances, because we had some extra wires, we just used the four wire for some of the regular outlets, thinking we would just not use the extra hot.  Not so fast.  We learned that once this comes into the power panel, it now requires a double pole breaker and we would actually have two 110v circuits in this one wire.   It actually worked out fine, allowing us to split the circuit over several outlets. The downside, however, is that it takes up more room in the panel box.

So back to the solar system.  The feed that comes down from the panels gets routed to the charge controller which optimizes and controls the charging of the batteries.  This power and all the power in the batteries is DC current.  The typical current used in homes is AC power.  The purpose of the inverter is to convert DC power to AC power.  Our inverter is a 48v, which is capable of providing a full 30 amp 220v into the panel.  When there is a load (a light is turned on, the freezer is plugged in, and so forth) the inverter reaches out to the battery, converts that DC power into AC and feeds the panel.

A few words about the battery install.  This was definitely the highlight and the “cool” factor of this system.  It was also the part that was not standard off the shelf.  We had to manufacture the terminal connectors from copper bars and then the mounting brackets from wood that we tied into the floor.  We actually have room to add two or four more modules if we needed to.

It took the entire next day to make all the final connections, test them, and mount all the components.  Using a small light bulb directly connected to the panel, we eagerly awaited the light to go on.  It worked!!  We had our own power station!!!!!  To monitor the solar activity, Liam set up a Raspberry Pi computer.  This system connects directly to the inverter and charge controller giving us web access to see what is going on.  Having a Raspberry Pi, with monitoring software, also opens up a whole new opportunity for our home automation plans (more on that in the coming weeks).

The system was working and we said good bye to Liam after several very long and hard days of work.  Perhaps the most exciting event for us was that the system generated 2kWh of energy, despite the fact that it rained the entire day.  Yes, on a day of rain!!!  We didn’t even see a ray of sun.  Now, that is awesome!

We officially cut the cord.

A few days later we had our welder in to make some adjustments to the floating stairs.  It was another rainy day. His grinder and other power tools were connected and used our solar power system, all day .  As he continued in the evening, we had our large shop light running as well.  Before he took off, we checked the status screen on the charge controller; it showed the battery at 95%.  Enough said – this darn thing works!

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.