Solar powered roof ventilators deliver superior performance over conventional whirlybirds when it comes to reducing the interior temperature. But how do they compare on price?
While solar panel manufacturing costs are reducing, a quality motor and solar panel will always be the most expensive components of a solar roof ventilator. Customers should expect to pay between $500 and $900 for a product that will last. When it comes to whirlybirds, a standard home needs 2-4 quality units (@ $200 for each quality whirlybird). A single SolarStar from Solatube Australia is, therefore, worthwhile in comparison.
When purchasing solar powered roof ventilation, the best way to know if you are getting value is by understanding the wattage of the solar panel and the diameter of the extraction fan. While there are other variables, this will provide you with the simplest and easiest comparison.
A solar panel typically comes with 10-15 years of warranty as standard; however, ensure you read the fine print since most will exclude components, usually offering 1-3 years on the motor.
Customers need to be careful about imported solar roof ventilators as they may not be built for the harsh Australian environment. A single, one-size-fits-all flashing creates similar issues with leakage as in traditional low-quality skylights. Consumers should always look for roof flashings that are tailored to the contours of their roof.
Wind vents are priced in the $80 – $350 range per unit. The average air volume is tested at approximately 80-100m³ per hour, which is relatively inefficient. Often these products will have similar performance to a static cap. They have been popular in the Australian market as they are cheap to give away with insulation and roofing packages.
Quality is a factor in the pricing of wind vents. Consider these aspects before purchasing one. For instance, does the unit include a fan blade, which will help improve air extraction? What’s the diameter of the product? For domestic homes, a diameter of 250-350mm is recommended. Is the warranty for life and does it cover the bearings? Low-quality wind vents are usually associated with seized or noisy bearings.
Budget solar roof vents are available at $100 – $250 per unit while quality solar roof vents cost $500 – $900 per unit.
When looking for any solar powered product, be prepared to spend extra for a quality system. Budget solar powered roof vents are available at low prices due to poor quality motors and solar panels, both of which can reduce performance, offer little to no benefit over a standard wind vent, and often have a warranty not extending beyond a year.
Roof ventilation and home temperature
Roof ventilation will definitely reduce the temperature inside the home. But it’s difficult to say by how many degrees the temperature will reduce as the answer depends on many variables such as insulation and roof material. For instance, tiles with sarking and Colorbond roof materials will hold in more heat while tiles without sarking will allow more cross-flow ventilation. The best way to check how ventilation will work for you is by measuring the temperature in the roof cavity – temperature in the roof cavity can easily reach 60°C; therefore, exchanging this air with cooler air from outside will have a major impact on the interior temperature.
How many eave vents do I need?
As mentioned above, variables such as sarking on a tiled roof can matter. The best way to tell is by opening the manhole in the ceiling. If you still feel that substantial air is being drawn through the manhole after the ventilation is installed, you probably need more eave vents.
Do solar roof ventilators run at night?
The operation of solar roof ventilators and whirlybirds is similar, the only difference being, instead of operating with the wind, they operate with the sun. A whirlybird will not operate on a hot and still summer day and a solar roof ventilator will not motorise at night. A wind vent has similar performance to a static cap; therefore, a solar roof ventilator will still allow natural air convection at night.
Battery backup is often requested by customers, but you should be aware of the pitfalls and weigh up the extra costs. Batteries often have a 1-year warranty, and depending on the quality, need to be checked and replaced every 1-2 years. Batteries may not be able to deal with extreme temperatures; in fact, there have been many recalls for roof space battery operated products due to fire hazards. Besides, a considerable amount of solar energy will be diverted to charging the battery rather than powering ventilation.
Overcast and rainy days
The SolarStar will still operate enough to pull moisture from your roof cavity but there is little need for it to run at full capacity on rainy days. Roof ventilators draw air from outside; therefore, the condition of the outside air will determine the impact on your home.