One of the most difficult parts of deciding to go off-grid has been the sizing of the solar system we will be using.  This is a pretty time consuming and sometimes difficult question to answer but in general what you are shooting to do is figure out how much power all the electrical devices in your house use, and use that as a starting point for all your calculations.

In some cases this is as simple as looking at your monthly power bill and it will generally tell you exactly how many kWh per month you are consuming.  If you are anything like us, in our city house we were using around 1000kWh/month or ~30kWh / day.  Of course this is in a large 4bdrm house with all electrical appliances, double oven, lots of computer gear running, and not a whole lot of attention paid to saving power.

Lets just go with the value of 30kWh / day for the sake of discussion here, though, we will be hoping to cut that considerably in our new house.  One of the more surprising things I’ve learned while embarking upon this house building journey is the large amount of government resources readily available on the web, free to use!  You can find all sorts of great information such as water well registrations (gives an idea how far we’ll need to drill to hit good water) but also information for renewable resources such as solar and wind.

One of the great tools for running some basic solar pv calculations is the venerable PVWatts provided by the National Renewable Energy Laboratory.  Thankfully the US Dept. of Energy has seen fit to share this super handy tool and outfit it with data points/locations around the world.  In our case, the closest city to us from the options available is Ottawa, Ontario in Canada, so we will pick “ON Ottawa” from the Canada drop-down and click the “*Start PVWatts For International Sites*” button in the bottom right of the form.  This tool may not look like much but don’t discount it’s value on looks alone.  There are only two values you really need to change on this page – the “DC Rating” in kW and the “DC to AC Derate Factor” – the default is 0.77 but this is for grid-tied installations, for off-grid we are using 0.52 – shows you how much power you lose converting DC to AC in an off-grid system!  You can also play with the “Array Tilt” value to see what impact different angles of your panels will have on your solar production – if you are doing a roof-mounted panel installation and you know the angle of your roof you can enter this value here.  For us, up here in the northern climate, we will choose a racking system that lets us switch between 45 degrees in the summer and the steeper 60 degrees in the winter.  By default you generally want your panels set to the equivalent of your latitude (f.ex Ottawa is at 45 degree latitude so a panel angle of 45 degrees is good.  However in winter when the sun is lower in the sky we increase the panel angle to 60 degrees to catch more of that light.)

For the DC Rating, you are basically going to play around with some values here to try to cover the 30kWh/day we talked about above.  So lets put 20kW as an array size / DC Rating and hit calculate; you’ll get back a list like the following:

If we examine the third column, AC Energy (kWh), we can see that for every month except November and December we exceed our target of 30kWh / day or ~1000kWh / month.  November is grim up here with an average of only 2.35 hours of sun per day – that’s not a lot of time to get a battery bank fully charged!

There’s a lot to talk about here – first off is that a 20kW array would be substantial – both physically and cost wise.  If you went for the cheapest / most readily available panels in Ontario right now, the Canadian Solar 250W 60cell panels, you’d be looking at around 80 panels and with a cost of around 76cents per watt, the array would cost around $15,000CDN.  Consider also, that decent racking for your solar panels costs about the same as the panels themselves so you would be up to near $30,000 for panels and mounting alone, with none of the other necessary equipment!

This also doesn’t factor into account that we ran the calculations at a fixed 60 degree array tilt to optimize our winter solar collection, but if we run it again using 45 degrees for the summer months you can see we are well in excess of our goals.  Just oversizing a system like this will cost an extremely prohibitive amount of money and will lead to a needlessly complex and large system.  We’ll talk a little more about this in another post but for now this one is getting a bit long, so I’ll leave it here.

Managed to get out and get the milk jug that we will be using to hold our mailbox painted up in between rain showers over the past few days. 

Now we just need a 4×4″ post and we’ll be off to the races!

As mentioned in a previous post, we have no grid power to our lot, it’s about 650m away and would require a fair amount of money to install, so we’ve decided to set up our house to be “off-grid”, using solar PV panels to charge a large battery bank which will then power standard electrical loads in the house through an AC inverter.

We’ll also have a backup generator (either gas or propane) to recharge our battery bank when there have been too many consecutive days without power.  I think we are going to go with approximately 8kW of PV panels, a 1300Ah battery bank, and a 6kW inverter.  I’ll devote a separate post to each of the main components of the system, and a complete system overview, in a later post!

Last Friday, May 2nd, we applied for our building permit.  We have almost everything in order and only need to complete one additional form regarding insulation R-values.  The building inspector mentioned that the hardest part about getting approved, is the septic system permit, which we already received from the Health Department, so there shouldn’t be any issues with the permit approval barring any unforeseen circumstances.

There are weight restrictions still in place on the rural roads around Merrickville, but as soon as those are lifted (next week or two) and we get our building permit, we can break ground!

First order of business is to find a good site surveyor to stake out the building site, then we can get the excavation crew in to prepare for the concrete forming / foundation contractors!

Getting mail in the country is a little different than getting mail in the city.  You have to install a mailbox per Canada Post guidelines for mail to be delivered.

If you’ve never received mail in a country mailbox before, you can both send and receive mail via your mailbox.  For outgoing mail, you put it in your box and put up the flag, when the postman sees the flag is up, they’ll stop and collect the mail on their way by.  When they deliver mail, they’ll also put up the flag to let you know there is something for you to collect.

You can install your mailbox in a number of ways but one of the preferred methods seems to be the use of an old milk jug – drop a 4×4″ post into it, fill it with concrete/dirt, and mount the mailbox on top.  The picture above shows our new mailbox and our milk jug which has recently been primed, after having been sandblasted to remove all the crud/rust.

In another post I’ll post some pictures of the painted milk jug, and a photo of the completed and installed mailbox.  We are just waiting on some stencils as we need to paint our name and civic number on the side of the box!

Today we met with our municipal building inspector to review our finalized house plans and ensure everything is on track.  The meeting went very well and it was nice to meet someone who we had only communicated with via email for the past couple of years.

We went over the plans in some detail and covered off insulation R-values, and also discovered that because we will have a forced air heating system, we aren’t required to have an HRV.  At this point I think we will still go ahead with the Lunos e2 HRV units (three pair) though.

We also discussed our zoning (Rural), and the relevant fees for building: $2200 development fee, $1000 performance deposit which is returned after house completion, and the building permit fee which is $12 per $1000 of house construction budget.

All in all a successful first meeting and, to me, signifies the start of the building process!

Just wanted to get out a quick update as to where we are at present.  Our main goal right now is getting our building permit from the municipality.  To get the building permit we need the following items, and I’ve struck out everything we’ve already completed.

• Two sets of construction plans, with a completed permit application form.
• A site plan showing:
  • proximity of all existing neighbouring barns and gravel pits/quarries,
  • location of all existing and proposed buildings relative to lot lines,
  • location of all power lines.
• Written approvals for roadway access from Provincial Highways, County authorities, or Township Roads Superintendent, as applicable.
• Health Department Certificate of Approval.
• Deed/title to the lands.
• Severance conditions.
• Ontario New Home Warranty Plan Act declaration.
• Payment of all permit fees.
• Soils report.
• Manufacturer’s specifications on both the heat recovery ventilator and furnace/heating apparatus.