Beyond South: lower installed costs with east-west facing solar panels

Moustafa YoussefBlog

In the northern hemisphere the sun travels from east to west in a southernly direction and so aligning solar panels towards south allows them to capture the most amount of sunlight over the course of a day and year than any other direction. However because east-west facing solar panels are pointing in two different directions they provide a unique feature that allows for lower installed and/or levelized costs.

As shown below, solar modules pointing east and west peak before and after solar noon. More energy is produced as the sun rises in the sky, increases in intensity, and points closer in the direction of a solar panel. So for example a five kilowatt solar array facing south at a low tilt can peak around 4.8kW by 1pm, but a 5kW array facing south-east (45 degrees to the east of south) might peak by 1130am and a south west array by 3pm.

east and west solar arrays peak before and after south arrays

east and west solar arrays peak before and after south arrays

The point being is that a single south facing solar array will peak once but an input composed of two solar arrays facing east and west will peak twice or at least make the peak a lot wider than with south facing arrays. Knowing that both solar arrays are not going to peak simultaneously means that we may be able to add more input capacity to the inverter, allowing it to operate closer to its rated capacity and enhancing its efficiency.

more solar panels east-west solar arrays

combined east-west solar arrays can improve the capacity factor of a solar pv system because they stretch the peak ofproduction

The design advantage of east-west facing solar arrays

The outputs of east and west solar arrays allow for a more stable power output. The higher the tilts and the further from south the more bipolar their total daily output becomes. Flatter solar panels peak closer together because their direction is closer to the sun’s travel path.

effect of east-west facing solar arrays on output

solar production of east and west facing solar arrays with different tilts


Feel free to contact us to learn more about the potential of your east or west facing roofs.

How Snow Impacts Solar Production in Alberta

Moustafa YoussefBlog

Snow Impacts Solar Production

A lot has been speculated about how snow impacts solar production in Alberta. In this blog post I’ll discuss the results of the effect of snow and tilt on the output of NAIT’s Solar Reference Array, which showed that snow incurred no more than 6% of loss on annual output.

Cold is good!

A 250W module (commonly referred to as a solar panel) or a 3kW array are going to produce said power under standard conditions which are a full sun intensity and a cell temperature of 25 degree Celsius (amongst other conditions). Higher operating temperatures lead to lower solar production and so lower operating temperatures lead to higher solar production.

This means that although solar panels receive less sunlight in the winter they produce more energy over the amount of sunlight they receive compared to warmer seasons of the year.

Production losses incurred by snow

The Northern Alberta Institute of Technology (NAIT) installed two solar sub-arrays facing south as shown below. One sub-array had its snow actively removed from it; the other sub-array was setup as the control and had no snow removed from it.


The NAIT Solar Reference Array which was built to study how snow impacts solar production in Alberta – The subarray on the left has snow actively removed from it, while the one on the right acts as a control.

A report was published after one year of observation and showed that losses incurred by snow are limited to a maximum of 6% of annual production. Below is a plot of  the array’s solar production and snow losses with increasing pitch. The angles mentioned in the report range from 14 degrees to 90 degrees.

How snow impacts solar production in Alberta


How Snow Impacts Solar Production in Alberta

First of all it’s important to note that roofs that have pitches that are close to 12:12 experience the maximum annual solar output which is about 1,300 kilowatt-hours per kilowatt per year in Calgary, or 1,200 kWh per kW per year in Edmonton.  If your roof only has a slight pitch of say, 3:12 your annual production is only 15% less. Interesting snow had the biggest impact on flat pitched roofs, specifically the 18 degree tilt. Panels flatter than that suffered less from snow because they didn’t capture that much winter sunlight to begin with given how high up they are pointed in the sky.

It’s not a big deal how snow impacts solar production

Solar is a great resource in Alberta and cold temperatures in and of themselves are good for solar production. Whilst the impact of snow has a detrimental effect on a solar panel’s power production, it incurs no more than 6% in losses of total annual production. This is because we are so high up north that most of the solar production is concentrated between the months of March and September.


Imagining Alberta’s Solar Future

Moustafa YoussefBlog

kinetic multi rail racking

After hearing what Albertans had to say the Climate Change Advisory Panel recommended to the Alberta government that coal fired electricity be phased out by 2030 by phasing in 50-75% of its supply with renewables. Many reports submitted to the Panel advised on how much solar should be installed in the years to come. The Pembina Institute in their report Power to Change, conducted a study where it was shown that four gegawatts (4GW) solar can be connected to the grid whilst phasing out the supply of electricity derived from coal. So we are going to install a lot of solar and of course there are different ways we can develop a transformational capacity.

transmission line anthony henday

A transmission line parallel to the Anthony Henday carrying high voltage electricity

Alberta’s solar future

If we wish, we can just build a few giant free-field plants as TransAlta has offered to do, or we can distribute solar over roofs across the province bringing generation – and its assets – closer to the consumer.

It’s too early to justify a target but let us try to imagine how four gigawatts of installed solar will look like. 1GW is equal to one thousand megawatts, and one megawatt (MW) is equal to one thousand kilowatts. Four panels have a rating of about one kilowatt (kW for short, has a total surface area of about 75 squared feet), therefore we are talking about installing around 16 million panels in the next 15 years! About one kilowatt or four panels for every Albertan. These 16 million panels are going to have a total surface area of about 24 squared kilometers, are going to cost us on the order of 10 billion dollars, and are going to produce about 5,000 GWh per year, about 10% of what coal fired plants are supplying today.

Alberta currently has 9.1MW of solar installed, which makes 0.3% of Pembina’s rather conservative target of 4,000MW. The 9.1MW that are currently installed are spread over 1,314 sites(personal communication, Howell-Mayhew Engineering, 2016), which works out an average system capacity of  7kW (28 panels per system). If the average system size installed over the next 15 years is 10kW then we are going to need to install 27,000 systems every year to have a capacity of 4GW by 2030. This may seem unrealistic given our demographics, the number of electricians, inspectors, truck deliveries we are going to need, the number of buildings there are, how much time we have, and so on.  So we can expect to see larger ground-mounted installations continuing to supplement rooftop residential and commercial installations that make up the bulk of Alberta’s escalating solar capacity.

Generation vs negative load

Larger systems of course enjoy economies of scale and more cost-effective, centralized technologies. However there are costs that are beyond the installation itself. For example a 500MW solar plant is going to require a transmission system to ship electricity to consumers, and given its size, it can be quite the distance. That transmission system and the local power grid at large also have to be able to handle an extra 500MW of added capacity. On the other hand, accommodating 500MW of solar distributed over thousands of sites spread across a grid that has a baseload of 6,000MW may not be a problem at all.

Connecting a grid-tied solar power system to an existing load is simpler because the wires to the grid are already there. All that is needed (from an accounting point of view only) is a new meter that measures the amount of energy exported from site. Solar is generated right where power is consumed and excess power is back-fed in the existing radial network. For example if a residential grid-tied system is producing more power than the home’s appliances are consuming at any point in time, excess power is transmitted to the neighbour’s home to feed their appliances. The neighbourhood as a whole uses less electricity, which is why electrical engineers can sometimes refer to distributed generation as a negative load. Residential solar has shown to improve real estate value because moving into homes that are going to cost less to live in on the long term is generally a good idea. Ethically speaking, it’s also a good idea since it is transferring capital – which gives power corporations market and political power – to the smaller consumer.

The Panel has recommended we merit projects based on their cost to taxpayers (a clean power call is defined as a reverse auction with bids requiring least cost from tax payers winning.):

Increased renewable generation capacity, with expansion linked to the phase-out of coal, supported by a clean power call through which the government will provide partial, long-term revenue certainty for renewable power at the lowest overall cost to consumers.

Today, small grid-tied systems are provided turn-key for $3 per watt. On the other hand the 2MW ground-mounted installation in Bassano was reported to be installed for $2.4/W. Systems with capacities between 10kW and 2MW will have a price range between these two.

Being innovative

One of the main cost reductions in ground mounted installations is the ability to use 1,000V inverters, which enable more panels to be connected to the same inverter. 1,000V inverters can connect about 70% more panels in series, allowing 40% in wire savings, a 2% improvement in efficiency, and an overall $USD 0.1/W reduction in system hardware costs (not including savings on labour).  Europe has allowed 1,000V DC systems on homes and shops since 2013, however in Canada there’s still a lot of work to be done. Coming up to standard on this topic can be a huge benefit to the development of distributed solar.

Installing a residential system on several different roof areas may have a lower output, increased labour and capital costs, but it also allows installers to be creative. The bigger the installation, the more repetitive and specialized the job tasks become. It might be more interesting for a project manager but for the most part on larger jobs, installers are typically hired temporarily and work in assembly lines which exposes them to one part of the project with rather menial job tasks.  The smaller the average installation, the more installations there are, the more creative installers have to be, the more there is to learn, and so the quality of training is higher.

Beyond the best bang for the buck

So we are going to install lots of solar in Alberta. What kind of jobs do we want to create for Albertans? What kind of training are these jobs going to be providing? Are we making the best of the technology that is available? Where are the millions of solar panels going to come from? Who is going to own these solar assets?

As mentioned the opportunity of going solar is a way for consumers to turn into micro-generators of renewable energy. They protect homes, businesses, churches, schools, communities, and co-op members, from the costs and risks of fossil fired electricity. Solar  – together with wind – can sustain Alberta’s legacy as an energy provider and, if done carefully, as a technology provider as well.

About the Author

Moustafa Youssef

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Moustafa is the owner and principal of Neighbour Power Inc.