6 things ballasted PV racking vendors don't want you to know

Racking (mounting) systems for photovoltaic and solar thermal systems fall into two basic categories: ballasted and penetrating. Here is a brief explanation of each:

• Ballasted - The word ballast simply means "weight added for stability". The concept is that a mounting rack, usually some type of metal frame, is arranged on the rooftop and instead of fastening it to the roof structure, it is held down by weights. The ballast (commonly concrete blocks) need to be heavy enough to resist wind, snow and seismic forces.
• Penetrating - This term applies to any type of system where the waterproofing membrane of the roof system is penetrated to make the attachment to the structure. Wind, snow and seismic forces are resisted by the mechanical attachment to the building structure.

Here's what the guys selling ballasted systems don't want you to know:

1. When they say "non penetrating", they really mean "mostly non penetrating" or "sometimes non penetrating. Ballasted systems do require mechanical attachment to the structure to comply with code if they are located in a seismic zone.
   
2. Future roof repairs and maintenance will be outrageously expensive. It would be great if roofs never needed to be worked on, but the reality is that every roof needs some maintenance and, unfortunately, occasional repair work. Roof work is expensive enough with a wide open roof. Now imagine paying someone to remove thousands of pounds of cinder blocks and disassembling solar arrays just to figure out where a roof leak is originating. Elevated racking systems can be easily worked around to keep the roof clean and well maintained.
   
3. Future re-roofing? Forget about it. You can't replace the roofing with a ballasted PV system in place. Well, actually you can, but nobody would pay the price. The labor to remove and replace the system and all the ballast blocks would be prohibitive. With a properly installed elevated racking system, re-roofing is very feasible.
   
4. Roof penetrations are a good thing. Every roof has penetrations. Every skylight, air conditioner, plumbing vent, electrical conduit, fan unit, etc. is a roof penetration. The roof penetration just has to be done right. Roofers know how to do it. The reason for the bad feeling in the industry about roof penetrations is because of all the poorly installed (and leaking) penetrations installed by people with no roofing expertise. Don't be afraid of roof penetrations, just do them right.
   
5. Ballasted PV systems block water flow. Good drainage is critical for a healthy and long lasting roof. The way ballasted racking systems sit directly on the roof with the cinder blocks spread out to hold them down, water cannot flow in the direction and velocity intended in the original design. Dirt and debris will build up around the obstructions and accelerate the deterioration of the roof membrane.
   
6. Elevated PV racking systems give you higher power output per square foot of roof. Ballasted systems need unobstructed roof areas because they can't span over pipes, vents, skylights and other rooftop equipment the way a racking system can. This can radically limit the number of modules you can fit on a given roof. Also, being so close to the roof and at a low angle, the modules will build up more heat which lowers efficiency. Elevated racks allow air flow keeping the modules cooler.
   

Welcome

Welcome to Silverback Solar blog! My name is Ryan Bruce and I am the founder of Silverback Solar and RoofScreen Mfg. Inc. This is our first blog post, so I thought it would be appropriate to answer a few questions about who we are:

Who are we and where did we come from: Lately there are lots of companies popping up and jumping on the solar and renewable energies bandwagon. We have actually been around for about 7 years under the name RoofScreen Mfg. We have been perfecting the art of modular steel framing systems for commercial rooftops with watertight roof attachments, and have become a recognized leader in that area. Most of our business has been in the design of facade walls called equipment screens, or roof screens, for concealing unsightly rooftop equipment from view.

In the past few years, as the solar and renewable energies industry has really started to gain traction, we have been designing racking systems for photovoltaic and solar thermal systems using the same technology of strong steel components and watertight attachments.

Why the name Silverback, and why the gorilla?: For a while, we marketed our solar racking products under the name RoofScreen, but found that it was confusing to customers. Even though the products are virtually the same for a roof screen or a solar rack, the industries are completely different. We decided to create a unique identity for the solar racking product line, and chose the name Silverback. One day, while trying to come up with a name and logo for the product, I stumbled across a picture of a silverback gorilla and it reminded me of the day I took my kids to the San Francisco Zoo. They have a silverback gorilla exhibit where you can stand by a glass wall, with the gorillas literally 4 inches away from you on the other side. I was struck by the shear size and power of the animal. I didn't think about it at the time, but later when I saw the picture, while thinking about solar racking, it clicked. The way a silverback gorilla stands with its powerful arms and legs, and the sloping strong back, correlated perfectly with the message we want to portray; bigger, stronger, able to span longer distances. Even the fact that the special galvanized steel tubing we use is silver in color fits with the similarities. So Silverback Solar it is. Why did we choose purple? That's just a marketing thing. The solar industry is saturated with yellow, orange and green logos. We just wanted to stand out, and we like the color.

What are our objectives?: There are literally billions of square feet of unshaded rooftops available for the application of photovoltaics and solar thermal installations across the nation. The problem is that many of them have skylights, pipes, vents, air conditioners, and other equipment preventing ballasted or those other wimpy style racks from being used. Enter Silverback Solar. We can span over and past the clutter to make use of those rooftops to provide the highest module density per square foot. So our objectives are pretty simple:

• Design and manufacture bigger, stronger racking systems for commercial rooftops
• Make the roof attachments watertight
  
• Provide project specific structural engineering and shop drawings so you don't have to
• Stock the parts for quick delivery

So that's my introduction to our company. I hope you check back periodically to see what we're up to.

Ryan Bruce