A question we encounter quite frequently in talking to home and business owners is: Does solar work for my roof? While solar systems work on most roofs the answer sometimes is not that simple. This is why I am going to shed some light on this issue to give you some tools for your own roof assessment.
1) Roof Pitch
The roof pitch is one of the factors that influences how much energy your solar modules will absorb. Keep in mind that we are trying to find a good balance between summer/winter. While some people are leaning towards your location’s Latitude as the optimum angle, there are others that deduct a number from your Latitude so the modules perform better in summer, when the bulk of the harvested energy is available. The reason why the optimum pitch is often below the Latitude for a location is the fact that a typical solar system in the northern hemisphere will harvest the majority of energy from April to October. Thus the modules need to be angled a bit less to hit the optimum for when the sun declination (the angle of the sun rays in relation to the equator) is quite high. Most industrial units have flat roofs and are ideal for a solar installation as the angle of the panels can be adjusted. At the end one should not put too much emphasis on this topic since most residential installations are roof-parallel. This means the pitch is given by the existing roof slope and can not be altered.
The best orientation of a solar module is facing towards True South. This is ideal as you can see in the diagram, the sun’s path changes from season to season. But with the cost of solar modules coming down, roofs that are facing towards the East or West, and even in some cases North-East/North-West exposures are still producing good return rates. Businesses with flat roofs are ideal as the solar power system can be positioned to suit the sun’s path irrespective of the buildings direction. How important this maximum efficiency of a solar system is, depends on the feed-in-tariff program and the overall system cost.
Shade on a solar module is not a good thing and must be avoided. Modules should only be mounted on roof spaces that are not affected by partial or full shading during the core hours (10am to 4pm) of a day. Even the shadow of a telephone wire can significantly reduce your energy production. It also needs to be noted that there is no inverter technology available that can generate energy from a shaded module, contrary to what micro-inverter supporters sometimes claim.
Solar modules can operate even at very cold temperatures. In fact the electric efficiency of a module increases the lower the temperature is. Most modules are rated for as low as -40 degrees C. Due to this effect you can expect very high power generation on crisp cold but clear days. Great for northern climates like ours in Ontario.
5) Dust and Dirt
Modules have a self cleaning effect when it rains. The tempered glass surface does not allow dirt and dust to stick to it once rain water runs over it. There may be exceptions when additional cleaning is required, i.e. farm operations or locations near major highways. Ensure that demineralized or rain water is used for the cleaning. Otherwise you may get calcium build up, negatively effecting the amount of light that gets through to the solar cell under the glass.
The Ontario government has made several ground breaking advances in promoting the development of renewable energy through subsidies with the FIT and microFIT initiatives. So popular has the program been that the Ontario Power Authority (OPA) has been overwhelmed with applications from home and business owners. This blossoming development has seen the renewable energy capability of Ontario increase to 1,300MW — enough to power more than 300,000 homes, making it one of the 10 solar hotspots in North America. The OPA has further guaranteed development of the Ontario economy by insisting that 60% of the solar power systems installed in the province be made locally.
The insistence on local content has made the province a viable and attractive prospect for solar companies. Companies like Canadian Solar, Silfab SpA and others have opened plants in Ontario in recent months, creating much needed ‘green collar’ jobs. The increase in contracts has seen solar installers popping up like mushrooms. Solar installers provide thousands of jobs in the solar power industry.
Another incentive for growth is the sharp decline in prices for solar power systems; PV solar systems cost half of what they did in 1998. A recent study by Duke University showed that the ballooning costs of nuclear plants last year resulted in the crossover eagerly anticipated by renewable energy companies for decades; solar is finally cheaper than nuclear! But trouble may be on the horizon. The McGuinty government has shown a strong preference for nuclear and gas electricity production, refurbishing two nuclear reactors at the Bruce power plant with plans to build two more. The opposition has shown strong resistance to the FIT and microFIT initiatives, threatening to scrap the programmes altogether. The OPA has also hinted at future reductions in FIT and microFIT subsidies which would slow solar power installations dramatically and lead to the closure of solar companies and a loss of jobs in the province.
The Canadian Solar Industries Association (CanSIA) represents various interests in the solar industry. Said ex-chair David Eisenbud; “By 2025, solar energy expects to be widely deployed throughout Canada, having already achieved market competitiveness and no longer needing government incentives. By 2025 solar will be supporting more than 35,000 jobs and displacing 15 to 31 million tonnes of greenhouse gas emissions per year, while providing a safer, cleaner environment for generations to come.” All this will be jeopardised should FIT and microFIT subsidies be halted or altered.
When the German government threatened to reduce solar funding, members of the solar industry and local communities campaigned to have their subsidies extended. So great was the support that the German government revised its plans. CanSIA is hoping to drum up similar support. To this end, they are launching the Stand Up for Solar campaign. A website, standupforsolar.ca, allows you to create awareness through social media sites like Twitter and Facebook and email or tweet your MPP to voice your support for the solar industry. If you want the government to vote for solar in the October elections, you will have to join those in the solar industry to make a stand.
Go to the website, donate funds or post the site on your social media outlets to spread the word.
This week we look at two brews which use their heads by utilizing solar power to bring you your favourite beverages.
There’s nothing better than relaxing with a nice cold beer? Wrong! Not when you can relax with a nice cold solar powered beer. The Sierra Nevada Brewing Company owns one of the largest solar powered systems in the U.S. Since 2008, this innovative brewery has been putting sunshine in your mug. The brewery’s solar power system consists of two solar arrays. The first is an array of 6 700 Mitsubishi, 185 watt lead-free panels which utilize the brewery’s ample roof space to produce 1.4 MW of AC power. This system is coupled with an additional 2000 SunPower, 220 watt solar panels. This array avails itself of an intelligent tracking system that angles solar panels to receive the most daylight. This increases output by up to 30% and provides shaded parking for staff and customers. The system provides 892, 859 kWh per year. Sierra Nevada brews several varieties of beer it’s most popular being the Sierra Nevada Pale Ale.
Brew number two is Solar Roast Coffee; the best coffee under the sun! Fair trade coffee is passé when compared to this feisty cuppa cooked up by brothers David and Michael Hartkop. The first coffee roaster was constructed from an old satellite dish and a colander and given the heady sobriquet Helios 1. It was made from 100 plastic mirrors and roasted one pound of coffee at a time. Subsequent models were more sophisticated and fruitful, but could not surmount the fact that Oregon has only three months of sunny weather a year. Meet Helios 3; this bad boy was constructed on a trailer, roasts five pounds of coffee at a time and folds up easily for transport to provide the general public with a cup o’ joe on the go.
Pueblo California was where the Helios 3 found its final resting place as the brothers Hartkop set up their first retail business. They now
use a solid wall of mirrors, mounted to the roof of their coffee shop to roast 30 pounds of beans in only 20 minutes. Solar Roast Coffee sales have soared and they have opened several retail outlets around the U.S. They also sell their beans on the Internet and are always looking for ways to improve their Helios. Remember; chicks dig it!