- Solar Resources in Southern Alberta and Calgary: Solar potential in Southern Alberta and Calgary is better and higher than Rio or Rome. Also, the panels are made out of silicon (the same material used in making semiconductors and electronics), so they perform better in lower temperatures and colder climate. A cold sunny day in Calgary is the near perfect condition for a solar system’s performance.
*images used with permission from energyhub.org
- The Annual Nature of Solar System Production: The Micro-Generation Regulation in Alberta dictates the nature of the interaction for grid-tied systems. Customers can only receive “credit” for the electricity that they export to the grid. This credit is calculated at the same rate as they pay and will be used against the amount of electricity they import, or consume, from the grid. Since the amount of electricity generated in summer months is substantially greater than what is produced in winter (because of the long summer days we have, and the high altitude of the sun during that time), the working of the solar system needs to be looked at as an annual cycle. The “credit” is built up during summer, and is used up during winter months, resulting in an annual balance in favour of the customer.
- Effects of Snow: While having panels covered by snow is less than ideal, the actual effect of snow on the performance of the system is not larger than 5%. Considering that the majority of the system’s production happens in summer months, this effect is considered negligible. The snow can be removed from the panels if it can be done safely and easily to avoid this effect.
- Hail Damage: The panels are rated and designed for any impact, including hail. In other words, they will not be easily damaged by hail. This form of damage to the panels is extremely uncommon in Alberta. And in the rare event when a panel is damaged by hail, they can be replaced by a new one since the panels have a 15-year warranty.
- Added Weight to The Roof: For residential installations, the most common and cheapest method is to install the panels flush against the roof. The system would be tilted as the same angle as the roof. The amount of weight added to the roof in these cases, including the panels, the racking system, and all other components, is typically around 0.4 PSF (pound per square foot) which is very minimal. For commercial installations, the size of the system and the required fortified racking system will add considerably more weight to the roof. Therefore, accurately calculating the added weight, and determining whether the roof can withstand the weight or not from a structural point of view, are necessary parts of the design process.
- Roof Penetrations:
- Asphalt shingle roofs: The shingles will need to be penetrated, however, the fasting hardware used are typically self-sealing, and added sealant and water-proofing materials are used to ensure these footings and the penetration holes are properly sealed up.
- Metal standing seam roofs: Racking systems are typically fastened to these roofs using brackets and clamps, without any penetrations.
- Flat roofs: Penetrating the roof depends on the racking system used. Ballasted systems do not require any roof penetrations.
- All other roof types: Other less common roof types need to be looked at on a case-by-case basis to determine the best kind of racking system for those particular applications.
- Replacing Roof: It is highly recommended to replace an old roof before installing a solar system. Removing the system to replace the roof is extremely labour-intensive and expensive.
- Electricity Bill After Solar: Electricity bills are composed of different charges. The electricity exported by the system only works towards offsetting the consumption cost, and portions of distribution and transmission charges. The local access fees and the administration fees are all fixed and won’t be cancelled out. As such, a ‘zero’ electricity bill will almost never happen.
- Optimal Tilt For The Panels: Generally speaking, the optimal tilt for a solar array is the location’s latitude plus 10° or 15°. However, in reality, this rule is rarely adhered to, and the main reason is the extraordinary wind load which roof-mounted panels titled at that degree create. The means to account for and accommodate this wind load are generally very expensive: the engineering work and study which needs to be done to design the racking system, the racking system itself and the reinforcement measures which need to be applied to the roof. This is all easier to do in case of flat roofs, and even then, the majority of installations on flat roofs are tilted at 10°-15°. For most of residential roofs, it is much cheaper and easier to install the array flush-mounted to the roof, which means the array’s tilt will be the same as the roof’s pitch.
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