Before installing anything on your roof, it must be assessed of capability to handle the load and the life left in your current roof. Most truss roofs should be able to carry the load. Some trusses may be borderline and may need an engineer's assessment. Normally solar panels only add the equivalent weight of a layer of shingles.
If you current shingles are older than 7 year and look poor, they should be replaced with 40 year fibreglass shingles or long life roofing. The load of the panel railing system must be supported by your roof's structural members, ie: your trusses or roof 2x4's or 2x6's. Every point load is then screwed into each truss and the tie point sealed with roof caulking. In our case, this tie in was verified by the installers, me and then the engineer. The tie point was further protected by a SS flashing which has a rubber seal where the mounting bracket for the railing goes. This gives a 3 point protection system which is never removed, even when you may have to replace your roof some 30-50 years later.
Our south facing roof is almost 100% covered with solar panels. What destroys roofs are UV radiation, heat and high winds. You must also have good air circulation in your attic. If the shingles are installed during warm weather, then they seal themselves from wind damage. Basically, the solar panels form a protective roof over our asphalt shingles.
So now you have a roof over a roof. Our roof is 95% shaded as best as possible. The temperature of the roof on a hot summer day is the same as that in the shade. Our Air conditioning load is thus greatly reduced. Further shading comes from mature trees on the west side of our home. Most days we may not even require AC
There is a 6 inch gap under the solar panels that will allow air to flow upwards cooling the roof further. Almost no snow accumulates on the roof. It accumulates on the panels and we remove it so that we can generate energy. The roof does get wet, but tar will repel water for a long time.
In addition, IMHO, the panel rails help to strengthen the structure by stiffening it. All components are either stainless steel, aluminium or copper wiring. These are all long life items. The panel railing system will outlast our house. The solar panels themselves can be replaced in 30-40 years if you are not happy with their output. Their output may decrease 0.5% per year or 15% after 30 years. Inverters may last 12-15 years and we recommend that you buy the extended warranty to make 20 years. The new smart inverters do not get hot. They lower the solar panel production output to maintain it below your nominal 10 kW rating.
Using SolarEdge with optimizers also lowers the voltage to 1 V DC at each panel when turned off. Fire-fighters will like this feature.
Conclusion:
IMHO, solar panels help you to maintain a cool roof and greatly extend the life of your roof. At the end of your 20 year contract, you grid tie and get pain 3-4 times what you use in your home. This should pay for all of your energy needs (electrical and gas). Electrically heated homes are not included here. You also save on your AC bill. The panels must be installed properly by an experienced installer.
So, I only see a win/win situation where your return is 100% guaranteed. Hydro-One put our monthly check directly into our account and we pay them for the power that we use like everyone else. Our last bill for our house electricity was reduced by 10% because of our green energy program.
Kirk is a retired Professional Engineer with experience in the Electrical Utility sector. We have no connection with Heliene, Silfab or Flexible Solar. We just believe that an informed consumer is the best consumer. Your results may vary from ours. All monitoring results were obtained from SolarEdge panel monitoring reported data.
More information:
If you are interested in installing a Microfit or Fit solar panel system, I strongly recommend giving Steve a call at Flexible Solar Solutions in Windsor, Ontario serving Southern Ontario. They are the best and most honest microfit solar panel installers that I have had the pleasure of working with. They will give you a straight analysis of your roof and what you can expect to earn. Don't forget to tell them that Kirk sent you. See my first post for more information on going Solar.
We expect to earn $6500-7500 per year depending on the weather for 20 years. That should work out to us having an extra $100,000.00 income for our retirement over and above your system costs. At that point we grid tie and earn the going rate of power which just might be very close to what we are currently being paid.
