Living in an Off-Grid Solar House – The Good, the Bad, and the Ugly

I built my off-grid solar home with my husband in 2003. The house was originally powered by a combination of solar and wind power. Living off-grid is an interesting experience.  Everything you do – cook lunch, have a shower, watch TV – it’s all powered by the sun or the wind. A pretty cool feeling – most of the time. Let me introduce you to the GOOD, the BAD and the UGLY.

We experienced them all one January in 2006. January 23 was clear and cold. A bitter wind raged through the bare trees and whipped the snow into eddies and drifts.  But for us, it was still a good day because the sunshine and horrendous winds gave us a record day for power. Not all days are like that.

This is what that a good day looks like to us:

A Good Day for Solar and Wind Power

A Good Day for Solar and Wind Power

You can see the sun rise in the first chart, see it start to produce more and more power until solar noon, then decrease again till sunset – a nice uniform curve. The jagged dips are from wisps of cloud crossing the face of the sun. The second chart shows the wind power – it is recorded in short intervals and what you see here in red is the maximum and minimum power for each interval, with a line in the middle for the average. You can see how variable the wind is, compared to the solar – it’s not the steady line or curve that you might expect.

That night the wind started to die down and the next day started out cloudy, with some clear sky later in the day.

A Bad Day for Solar and Wind

A Bad Day for Solar and Wind

But this is not the worst it can get. Imagine a day with no wind and it’s snowing. Here it is – the UGLY day.

An Ugly Day for Solar and Wind

An Ugly Day for Solar and Wind

Fortunately, we don’t see many days like this – but notice, there is still some solar power, even when it’s snowing.  It is for days like this that an off-grid system has a large battery bank to see you through. In January, however, that may not be enough to carry you through all the bad and ugly days so a backup generator is also part of the system.

This is what the whole month of January can look like (2006 had an unusually cloudy January).

Our Solar and Wind Power for January 2006

Our Solar and Wind Power for January 2006

The yellow bars show the solar power we received, and the blue bars represent the wind power. Add the two together and you have the total power. You can see January 23, the GOOD day, as a very tall bar – we produced 12 kWh of power that day. We only need 5 kWh a day to run our house so we stored the extra in our batteries. The next day was the BAD day – you can see how short that bar is in the chart. The UGLY day was January 13 – a very short bar indeed.

This was the worst month of the year. Most months there is plenty of sun and wind to supply all the needs of our home. That is the story with off-grid homes – you can store power for a few days, but there is no way to store all the extra power from the summer for months like this. That is the big difference between off-grid and grid-tied systems. Grid-tied systems are connected to the utility grid and, where net metering is offered, you can use the utility grid to “store” excess power that you produce in the summer for the winter months. This is done by giving you credits on your bills for the extra power.

As I am writing this, we are having one of those ugly days. Our wind turbine is not turning and we are having our first snowfall of the season. But it’s been a long and beautiful summer and fall. Like farmers, we have to work with the vagaries of the weather, but we enjoy the rewards of being self sufficient, environmentally friendly and never having a power outage.

 

Off-Grid or Grid-Tied – What’s the Difference?

Solar Power Array on the Experimental HouseSolar Power Center“I want to go off-grid and use solar instead of bringing in SaskPower!”

The desire for independance prompts many a call to Suncatcher Solar from people who want to be self sufficient and hope that solar power holds the answer to that dream.  But what does that really mean? What’s the difference between “off-grid” and “grid-tied” and what kind of lifestyle does each one entail?

What Does it Mean to Go Off-Grid?

Going off -grid means going it on your own. You have to produce and store all your own power and if you run out you start up the backup generator. There is no power utility to fall back on. On the other hand, neither is there a power bill.

Basic-Solar-Power-System1-e1318386617230

Off-Grid Solar and Wind Power System

An off-grid system needs a storage system for the electricity that you produce so that it will be available for times when there is no source of electricity. This storage system is one of the main features that distinguish an off-grid system from a grid-tied system. The other is a backup generator for long periods of cloud or calm.

The figure at the right shows the basic components for an off-grid system. A solar array and an optional wind turbine provide electricity to run the appliances in your home. Whatever you don’t need immediately is stored in the battery bank. Since you are completely reliant on your own resources the battery bank must be large enough to see you through at least 3 days without any solar or wind charging. This typically means very large battery cells forming a bank that requires a space that is a minimum of 2′ wide by 4′ long and 3′ high.

Remote Solar Power System

Remote Solar Power System

You will need to plan your energy use using a load analysis so that the charging system and battery bank is large enough to meet your needs. Heating your home in a cold climate will present some challenges. Some heating systems are difficult or prohibitively expensive to operate with an off-grid system. For example, you cannot run a geothermal system with off-grid power – the power requirements for the pumps are too large. Passive solar design and an in floor heating system are usually the best options for off-grid systems.

What is a Grid-tied Solar Power System?

Grid-tied Solar Power System

Grid-tied Solar Power System

A grid-tied system is connected to your electrical utility company’s power “grid”. The utility is now your backup generator. There is a basic monthly cost for a grid connection (usually around $25) but this is much less expensive than the $6000 or more for a generator and the fuel that the generator uses.  You can see the utility meter and subpanel for the large solar array shown in the photo on the right.

Grid-tied Solar Array

Grid-tied Solar Array

A grid-tied system often includes a net metering agreement. This means that when you produce extra power you can feed it back to the grid and receive a credit on your power bills for those times when you use more than you produce. Some utility companies may also pay you for your excess power, or buy power from you at higher than the going rate (this is called a Feed-In Tariff ).

Grid-tied solar power system

Grid-tied Solar and Wind Power System

The grid now also becomes, in a sense, your battery bank. Because you feed back your excess power for a credit, it is effectively “stored” for you until you need it. Usually this means that you feed back extra power in the summer and then use the credits in the winter when you need the power for your heating system. This is much less expensive than buying and maintaining a battery bank.

Looking at the figure on the left you can see that the grid-tied system is the same as the off-grid system but without the battery bank and its charge controller and without the emergency generator.

A Cost Comparison

This means that it is much less expensive to set up and maintain a grid-tied system. It also means that most of your money is going to what you really wanted to buy in the first place – solar and/or wind power. The inverter system, which converts the DC solar power to normal household AC power, is the only other expense for materials. Installation is also less expensive if there is no battery bank, charge controller and generator to install.

This typically makes a residential grid-tied system at least $15,000 less than an off-grid system. So why would you want to invest in an off-grid system?

Off-grid systems are still cost competitive if you live sufficiently far from the closest grid connection. If you need to have power brought in it may cost you at least as much or more to connect to the grid as to pay for the batteries and generator required for an off-grid system. If it will cost you $20,000 or more to bring in power, for example, the off-grid system quickly pays for itself, especially since there will be no ongoing power bills.

A Benefits Comparison

Off-grid System Pros and Cons:

Off-grid Battery Bank

Off-grid Battery Bank

Pros:

– ideal for more remote situations where power is expensive to bring in.
– no power bills.
– no power outages.
– self sufficiency on a clean, renewable energy source.

Cons:

– batteries and generator are expensive and require maintenance.
– lifetime for the batteries and generator(10 – 15 years) is less than for the solar array (35+ years) and wind turbine (20-25 years).
– no seasonal storage. Batteries can only store power for a few days and have a maximum capacity. When they are full, the rest of the power is wasted unless you can find an immediate use for it.
– power use must be carefully planned.

Grid-tied System Pros and Cons:

Pros:

– easy backup from grid power.
– eliminates need for expensive batteries and generator (which also requires fuel).
– provides seasonal storage if a net metering or Feed-in Tariff program is available.
– maintenance free for a solar power system (wind requires some maintenance and repair).
– internet monitoring available with inverters designed to be used for individual solar panels (Example).
– you are providing clean energy to the grid.

Cons:

– power outages. When utility power goes out your system also goes out unless you invest in a battery bank. This is a requirement by the utility company and is for the safety of those repairing the system.
– you still have to pay the basic utility bill, just not for whatever power you’ve produced.
– you are still using non-renewable resources when there is no solar or wind.

Making the Choice

Choosing the power system that’s right for you depends on your building site and the lifestyle that you prefer to live.

Contact us and discuss the options with us.

Solar Power Mounting Options

Solar panels take space – 400 to 1200 square feet or more, depending on how much solar electricity you want to generate. If you want to get top solar production in Saskatchewan, the panels should face due south and at an angle to best capture the sunlight.  But what, exactly, is that angle?  The sun moves across the sky during the day, constantly changing position.  It is also much higher in the sky during the summer than it is during the winter.

1.  Solar Trackers

Solar Trackers

Solar Trackers

A system that tracks the sun would be an ideal solution.  However, a tracking system needs a massive mount to accommodate all the panels and a complex control system to make the tracking automatic.  This makes the system expensive and the moving parts will require maintenance.

Solar panels have come down in cost so much that it is far cheaper to buy more solar panels and put them on a mount that is fixed at an angle that provides a good compromise.  Typically, for the 30% extra power production that you can get from a tracker, you could easily buy 50% more solar panels if you have the room for them.

Solar trackers do make economic sense if you are short of space or if there is a reason to squeeze maximum production out of a fixed size of solar power system.  This is the case, for example, in Ontario, Canada where the feed-in tariff pays a premium rate for systems up to 10 kW.

2. Roof Mounts

Solar Power on House Roof

A roof clear of obstructions is best for mounting solar panels

The least expensive way to mount your system is directly on your roof.  The mounting system fastens to the roof trusses and provides rails on which to mount the panels.  The rails keep the panels a bit above the roof itself to provide ventilation for the panels.  Solar panels are more efficient at lower temperatures, so ventilation is important.

A simple roof mount is the way to go if you have enough south facing roof space at an angle approximately equal to your latitude.  If this is a grid-tied system a lower angle can also work well since you usually produce a lot more power in the summer when the sun is higher in the sky.  With grid-tied systems you can usually feed that extra power back for credits in the winter or sell it back to the utility.

Ballasted Solar Mount for a flat roof

Ballasted Solar Mount for a flat roof

If your roof is flat, or just doesn’t have  a steep enough slope, the roof mount angle can be adjusted to compensate for that.  This adds some expense, but can significantly improve the production.  Ballasted roof mounts, that don’t require any roof penetrations, are also available for flat commercial roofs where the possibility of leaks is a big concern.

Keep in mind that you also want your solar array to be free of any shading.  Watch for dormers or trees or a roof on a more southerly part of the house that might shade your panels.

3. Ground Mounts

Ground mounted Solar Array

Ground mounted Solar Array

Perhaps you have no suitable roof space but lots of room on the ground.  This is often the case on acreages and farms.  A ground mounted array is the second most economical choice.

A rack for the panels is set up at a suitable angle and mounted high enough above the ground to account for snow cover.   The racks require more material than a sloped roof mount, so this adds some expense, as does the screw pile foundations.

Ground mounted arrays have their advantages.  You can more easily choose a good location with minimal shading.  The array is also easily accessible for cleaning and clearing off any snow cover that accumulates on the panels.

4. Pole Mounts

Solar Panels on a Pole Mount

Solar Panels on a Pole Mount

Another alternative for smaller solar power systems is one or more pole mounts.   These are like a tracking mount but without the expense and complexity of the tracking system.  Pole mounts are more expensive than ground mounts but can be manually adjusted for seasonal angles.   It is also easier to select a good location for a pole mounted array.

The limitation with a pole mount is that you don’t want to mount too many panels on one pole.  The array of panels is like a sail in the wind, so the larger the number of panels you mount on a pole, the more massive the pole and foundation will need to be.  The other alternative is simply to use more pole mounts but each mount will need a pole and concrete foundation, with its attendant costs.

Contact Us for help in choosing the best solar mounting system for your home.

Solar Panels and Hail

 

Everyone who has talked to us at Suncatcher Solar about solar panels invariably asks about hail. It’s an understandable question. Canada, especially around Saskatoon, and the rest of Saskatchewan can’t go a year without hail of some sort. These panels are supposed to last a long time, and the majority of the front face is glass. Glass that is going to be outside, with no cover or protection above it. Hail can cause a lot of damage, it can ruin entire crops, total off vehicles, and destroy siding and shingles.

What makes solar panels any different? Well for one, solar panels are built to last. They use tempered glass instead of plastics or regular plate glass. Tempered glass is much more resistant to impacts than regular glass. It’s able to with stand impacts at twice the speed that would break regular glass. If you know your physics (F=mv2), this translates into being four times as tough.


How tough are solar panels? Watch the video above of a solar panel taking a direct hit from a ball of ice the size of a billiard ball at 120 kph.

Hail isn’t as perfectly spherical or solid as what is shown in the video. It’s loosely held together, has many weak points and a lot of air trapped inside. Also, panels are rarely mounted in such a way that they would take a direct perpendicular impact from hail. Hail impacts will generally be at an angle, sometimes as much as 45 degrees – that’s more of a glancing blow than an impact. The one weakness of tempered glass is its edges. Impacts here can cause the entire sheet to shatter. This is why solar panels also have an aluminum frame. Aluminum keeps the weight down, provides corrosion free protection for the edges of the tempered glass and is a convenient mounting surface to secure the panels. Solar panels will last just as long if not longer than any other feature on the outside of your home.

Come hail, wind, rain or snow – solar panels do their job.