Sunday, May 27, 2012
Roof and Solar Install
Schuco rails are heavy duty. We received our rails from our supplier DTE Solar's old stock. This was fortunate since the rails were a full 20' long. The new products out there are apparently available in standard 10' lengths only. Longer lengths are special order. I was glad we were able to get these longer lengths. The L brackets, which are attached to the roof throuth the shingles and into the rafters with 1/4" x 3.5" stainless lag screws are mounted along each rail, 4' OC. Pre-drilled mounting, with a special flashing that tucks under the shingles and sealant is applied under the brackets as well. This is a long and messy job - the mounting of all these brackets. It is also very permanent. Once in place, it becomes an issue to repair the roof under these feet. And all the traffic on the roof in warm weather has really worn down the shingles. Especially near the scaffold. However, we are expecting the shingles will last a long time due to their being protected a great deal by the panels.
Note: We originally intended to go with a standing seam metal roof. Price for our Vicwest Tradition 100 22ga painted steel roof was $7.50/SF (this is a very thick sheet metal gauge for steel roofs), compared with $2.30/SF for the shingles (including full Ice and water on the south side and ridge vent). Major difference in cost, but we were totally willing. It would have been an excellent looking roof, but also extremely long lasting, recyclable, good for rainwater collection (no much concern of the tar from shingles), and waterproof. In addition, the solar panels would have been mounted directly to the steel seams with S-5! clamp mounts, giving a very sleek and low-profile integrated panel install. Unfortunately, the timing didn't work out and we had to meet our microFIT deadline, so we went with a shingle roof (not to mention we are elated at the cost savings).
HOWEVER: One thing to keep in mind: The metal roof with the S-5! mounting would have been a very versatile roof/solar system, because the S-5! clamps can mount anywhere along the seams, and there are no penetrations through the roof. The rail system is quite a downgrade (although significantly more expensive than the S-5!) in my view because once those rails are in place, they are not moving. Whatever the future brings, it must go on those rails. And one thing I'd like to see in the future is that we increase the number of panels on the roof - no chance with those rails - with the S-5!, it would have been simpler, I think. I do foresee that people will want solar PV even beyond the microFIT limits. I certainly do - the cost is so reasonable right now, and I feel it can be made even cheaper by not using the inverters - for example solar PV water heating can do fine with DC - no need for AC.
The panels are on a portrait layout, 3 rows of 15 panels for a total of 45. 6 Rails, 2 for each row of panels. The rails have a splicing hardware which is basically a bar that slides into the rail grooves and screws in place. Note, with the metal roof and S-5! clamps, it would have been a landscape layout. We have two 5kW 'Power One' inverters for a total output of 10kW. The array is rated at 250x45 panels for total of 11,250W. One is allowed to install up to 12kW for a 10kW system capacity. We could add 3 panels to the system - perhaps on the garage in back? Each inverter takes 2 channels of DC input. We have therefore divided the array into 4 blocks - 3 with 11 panels and one with 12 panels. This uneven-ness is no problem for the inverters to handle (without any loss of energy to speak of).
What is annoying to me is the system architecture mandated by the MicroFIT program. It centres around this Anti-Islanding feature. Simply, the system is not configured (and cannot be configured, I'm told) to provide the homeowner directly with power, bypassing the grid. In other words, the array serves the grid only, and the inverters shut off automatically if they detect no grid. This means they cannot be used to provide the household with power. Personally I hate this - it means there is no redundancy benefit for the owner. When the grid is down (during a blackout), so is our own generation system. This serves to protect hydro workers from being exposed to electricity while they repair the grid. Investigation is needed to see if there is a safe and legitimate way around this.