We heard from our kit house supplier today, that our windows and doors will not arrive in time for the original shipment (planned delivery of Aug 8th).  So at this point we encounter our first real delay on the project, but, it’s not so bad, the kit is now going to get delivered either August 14th or 15th (expect a flurry of updates after that!)

Because we don’t have a set project timeline this really isn’t too much of an issue.  The only time constraint we have sort of self-imposed, is that we want to be snug in the house before snow falls (even if the interior is not 100% complete), as we can’t really weather sub-zero temperatures for extended periods in the RV – it does have a propane furnace that works great, but not much insulation, so we go through propane at a ridiculous rate when we have to heat the RV.

A few people have asked for some more information about the kit house we are getting.  We did a lot of searching and talked to several local kit house companies, but most of these places want to sell you a “kit” that they assemble, and are selling these kits at a crazy premium – in most cases looking at their prices you might as well just go buy an existing house, there are no cost savings to be had with this approach.  While this might work for some people, we were more interested in being more involved in the building process by doing as much as possible ourselves – certainly we will not be able to do everything, but we can have a lot of fun (and save a ton of money) by doing lots of the work.

We researched a whole range of domiciles – everything from these sweet dome house kits they make out in Cali, to houses made from shipping containers (check out this really nice one built in Quebec), and then to more standard, local Ontario options like Linwood/Guildcrest/Viceroy.  We ended up selecting a kit house manufacturer based out of New Hampshire, called Shelter-Kit, for a number of reasons but the first and foremost is that their kits are 100% designed from the ground up for DIYers.  They also offer highly insulated designs (extremely important when off-grid) such as double-stud exterior walls with no thermal bridging.  We worked with them to design exactly what we wanted – a small-ish 40’x32′ ranch style house with a screened in porch out front, and a full height basement.

Here’s the front elevation plan of the house:

We settled on this design largely for it’s simplicity and ease of construction – we are hoping to be able to do a lot of the framing, roofing, insulation, and also the electrical and some of the plumbing (particularly the plumbing required for our radiant heating system) ourselves, so we’re very pleased we found Shelter-Kit and are looking forward to the arrival of the kit so we can get started!

Thanks for reading!

The last post I’ve been meaning to put up is about the battery bank.  This is the final part of our off-grid system, and one of the most important.  There are a whole bunch of reputable battery suppliers out there, such as Trojan and Crown, which are commonly used.  Also available, and what we are going with, are Rolls Surrette – we chose these because they are made out east in Springhill, Nova Scotia – and we like that our money goes towards Canadian jobs (especially out east where they really need them!)  They are also extremely highly rated and have a 7yr warranty (though many people get 10-15yrs out of them).

We are going with the S-1860’s (PDF link) – these are 2V batteries with a 20hr rating of 1445Ah.  To create a 48VDC battery bank we will need to connect 24 of these in series!  These batteries are enormous – weighing in at ~130lbs each, and about 17″ x 7″ x 12″ – we’ll have to construct a fairly large insulated box for them just outside the utility room, to get them as close as possible to the inverter.

Not a particularly exciting topic, however one of great importance to the off-grid system – without the battery bank we would need to run the generator 24×7 – not really practical nor cost effective (though, still cheaper than our standard utility bills for our house back in the city).

Thanks for reading, and I’ll have a more picture heavy post soon (I know people like these more) – we got our main water line installed between the well and the house, and also have the expansion tank connected, so there’ll be an upcoming post on that soon enough.

After posting the last entry, I realized that I should probably briefly talk about our house wiring – even though we will be off-grid, we still want to be able to run and wire our house for regular appliances and lighting.

In years gone by when people went off grid, they would in many cases use DC lighting and DC appliances, to avoid having the costly inverter in their system.  There are a few problems with this: DC wiring runs have higher losses so distance from the battery bank becomes an issue, DC electrical devices are less common, and the ones you do find are lacking in modern convenience and visual appeal (and are more expensive), and lastly, if you ever did want to connect to grid power at some later point, you would have to rewire your entire house.

Instead, we will wire the house for standard 120/240VAC, be able to use all regular lighting and appliances (except for a gas range, instead of electric, and a gas clothes dryer as well), and if we ever choose to connect to the grid down the line, we’ll be able to do so with a minimum of hassle.  We’ll just run the output of the Xantrex inverter into our standard electrical service panel as though it was a grid power connection.

Thanks again for reading!

Just wanted to get a quick post up covering the core components of our off-grid system – by core components I am referring to the inverter and it’s accessories such as the charge controllers, auto generator starter, and so on.

For a bit of a preamble: the basic premise of an off-grid system is that you have a battery bank to draw on (charged from either the solar array or the generator), and connected to the battery bank is a pure sine wave inverter (MSW or modified sine wave inverters are available, and cheaper, but they produce lackluster power that doesn’t run all appliances well) which is responsible for converting the battery bank power (48VDC) to AC power (120/240VAC) to run our house.

Selecting an inverter is based on a number of factors – budget probably being foremost, but our selection criteria also included the following, listed roughly by importance:

• Continuous power supply
• Surge power supply
• Integrated accessories such as charge controllers, auto generator start, and network monitoring
• Reliability ratings, reputation of manufacturer (availability of repair parts)
• Ability to “stack” inverters for possible future expansion

To satisfy the above criteria we considered Magnum Energy 4000W inverters, and also the Xantrex 6000W inverters.  In the end we chose the Xantrex 6000W inverter as it was most suited to meeting our current and future needs.  While the Magnum inverters are less expensive, we would have needed to start off with two 4000W inverters as I don’t think we would be able to get by with just 4000W continuous load.  Furthermore, the Xantrex inverter has a 12000W surge capacity and can carry that load for a lot longer than the Magnum.  Lastly, the Xantrex’s “load support” feature seems to be more advanced than the Magnum and that would come in really handy if we need to run some really heavy loads.

Our total lineup of Xantrex products is as follows – and I’m just linking out to these on the Northern Arizona Wind & Sun website as that’s where we bought them from – on a July 4th sale, including freight shipping, it came out cheaper than getting them from Canadian suppliers.

• Xantrex 6048 Pure Sine Wave Inverter
• (2x) Xantrex 600VDC, 80A Charge Controllers
• Xantrex System Control Panel
• Xantrex Power Distribution Panel
• Xantrex Automatic Generator Start
• Xantrex Network Monitoring Combox

Also, Northern Arizona Wind & Sun has a great set of forums with tons of helpful members, I highly recommend it if you want to do some more reading on some practical topics.

At any rate, with the above setup we should be plenty good to start, and we can always add up to two more inverters and more charge controllers, if necessary.  I think we will probably be ok with the above but we’ll only really find out once we get the house built and start living in it!  Because the inverters are the core of the system, we will probably purchase a second unit to have available as a standby in case the installed one fails.

Thanks for reading and I apologize for the lack of pictures, but I did promise to do some posts on this stuff previously and I wanted to make sure I followed up!  Again – any questions, hit up the comments section below, or post on Heather’s facebook!

To power our off-grid system, we will rely on solar panels to recharge our battery bank, and, when there hasn’t been enough sun to fully top up the batteries, we have a backup generator that we will use to provide additional recharging as needed.

We can also utilize our inverters “Load Support” feature, whereby if we want to run more electrical devices than our inverter can power alone (6000W), the inverter can pair it’s output with the output from the generator (7000W) to provide power to provide a total system power of 13kW – no doubt this will take care of anything we might wish to run!

Our generator is a Honda EU7000is, which is an inverter type generator that produces a 60Hz pure sine wave electrical output at 120/240VAC, just like the electrical grid.  Right now we use this generator to power the RV (TV/Satellite PVR, Microwave) and my tools (like my table saw, compressor, etc), but when we get around to wiring up the electrical, we will hardware this into our inverter with an automatic generator start circuit so the inverter can bring the generator online as necessary to recharge the batteries, etc.

For our solar array, we are going to start with 26 panels – these are Canadian Solar 250W panels which are currently selling for around 79cents/watt.  This will give us an initial array size of 6500Watts.  We’ll wire this up, for two strings of 13 panels, each string will run to it’s own 80Amp charge controller (connected to the inverter), for a total charging capacity of 160Amps (this is a maximum which will probably not often be seen).  We will start with these panels and see how we get on – if we find we aren’t generating enough power (ie. generator is running too much), we can always add more panels.

Our goal is to be able to support a power draw of around 10kWh/day, or 300kWh/month (a third of our power use in the city!) – so if we look back at the PVWatts tool I previously mentioned, putting in our array size of 6500W with a derate of 0.52 (for off-grid calcs), and a fixed array tilt of 60 degrees (best winter angle, still good enough in the summer), we can see that we are pretty good, except of course for November with it’s particularly meager solar insolation.

What I also find interesting is that March and February are the two highest solar producing months in the Ottawa area.  I would have initially thought that June and July would hold that position.

Anyway that’s some information about our solar panels and our generator setup, if you have any questions feel free to post them as comments and we’ll be sure to respond!

Well today was the day the basement floor slab was poured.  In preparation for this, I cut through my 4″ of rigid foam at the location where our four support columns will be located, so that they will sit directly on the concrete footings, and inserted a segment of 4″x4″ post in each one.

Before putting these placeholders in place, I wrapped each one in my 6mil poly vapour barrier, which concrete won’t stick to.  This should make it easier to pull these out later when we are ready to install the four support columns.  I also wrapped the bottom of the 2″x10″ that is supporting the manifold so I can remove this more readily later.

I also took the opportunity to ensure the radiant heating system was still pressurized to 80psi for the pour (to ensure the concrete doesn’t collapse the tubing).

This morning the concrete crew showed up bright and early and got right to work.  They backed the truck right up to the house and were dropping loads of concrete directly from the truck into wheelbarrows, which they would then transport across the basement and drop it where needed.  The following gallery captures some of the progress of the pour:

After the concrete is poured, they give it what is called a “hand trowel finish”, really this is done by quite a crazy little gas-powered machine with four paddles that rotate to smooth out the concrete.  They go over the floor a number of times with this machine and in the end the floor is really smooth.  Here’s a short little video of them in action:

Because it’s quite sunny and warm today, especially in that basement with all that insulation, the crew advised that I keep the concrete watered down a few times a day to slow the concrete curing and ensure it cures with maximum strength.  Heather took a couple pictures of me carefully dousing the concrete (thank god we can get water from our well!)