This webinar was recorded on Thursday, May 19, 2016.
Click here to watch on demand.
Utility-scale and commercial solar project installations can pose unique challenges and the devil is always in the details. Join us in this webinar as a leading EPC discusses how they resolved racking and installation challenges. We will highlight milestone solar installations and walk through aspects of each, including a 17 MW project that effectively addressed irregular terrain and the protection of a regional endangered species.
You will also gain insight on:
- How to reduce risks and save money on PV foundation design
- How this EPC expert dealt with challenging site conditions (including sloping terrain, ground clearance issues, etc.)
- How services can increase your capabilities and cut costs (value engineering, project management, etc.)
Solar Webinar Q&A
The following are some of the top questions asked by attendees during the solar webinar:
Q: What is the reliability of the main components of the tracking system and how easily can they be replaced if needed?.
A: All the main tracker components are industry proven and commercially available components that have undergone extensive testing for proven reliability. The system itself has undergone extensive wind tunnel testing to assess the dynamic wind effects on the tracking system. We are also engaged currently with Black and Veatch on a bankability study that will further validate the reliability of the components and the system. Replacing the main components is a very quick and easy process. Since all rows of the tracking system are open, a motor or controller can be easily swapped out in a matter of minutes.
Q: What was the ground clearance before the endanger species requirement was factored in?
A: Normally the leading edge is 18-24 inches. By raising the level to an average of 42” at the leading edge it allows for the re-establishment of the vegetation, which allows cover and protection for the tortoises from predators when they are out of their burrows. To encourage vegetation re- growth, we did everything we could to keep the root structure in place.
Q: What is the wind withstand of your installation?
A: The system that was supplied for the Bombard site in NV was designed to withstand 90 mph winds. Higher wind accommodations can also be made project specific.
Q: What was done to the fence to allow passive tortoise access? Did this add additional security concerns?
A: A 12”H x 12”W was installed in the fence every 250 feet to allow free access in and out of the acreage by tortoises. This does not warrant any security concerns.
Q: What is your normal pile depth?
A: Pile depth varies depending on a number of variables such as the location of the project, configuration of the racking system, tilt angle and ground clearance. Another important factor is the soil type, which varies greatly from site to site. On average our typical post driven I-Beam is between 12 feet and 15 feet in length.
Q: Were there any concerns or important items to consider in getting a geotech report for a large site which may be measured in square miles instead of, say, a smaller 2 MW array which may be a few acres?
A: By using an established and reliable Geotechnical and Environmental Sciences Consultant we were able to assure any and all concerns were addressed.
Q: Do you have a single axis tracker?
A: Yes, we do offer a single-axis tracking system. Our TDP Turnkey Tracker is a distributed tracking system designed for 1-10MW sites and is offered with a full suite of services including layout, design, installation, and commissioning. Find out more information about our solar trackers.
Q: What’s the incremental cost of adding tracking? What’s the breakdown of added labor vs. equipment costs for trackers?
A: There is an added cost when going from fixed tilt to tracking systems when looking at the equipment costs alone. This cost will vary by location and other site-specific factors. It is often offset by the increase in production. The added installation falls mostly in the wiring and commissioning of the system. All of these factors need to be determined when assessing the project plan. The equipment costs need to be factored into the additional output generated from that specific site and the analysis needs to be done at that time.
Q: Do you have any projects in the New Jersey area?
A: We do! We currently have 62MW of installed capacity in over 25 projects in the state of New Jersey including both ground penetrated and ballasted systems on landfills. Please contact us if you would like more information on these projects or if you have a project in the area that we can help you with.
Q: For your fixed tilt 2×9 system, what it the weight of the unfolding components? Is a crane required?
A: This system is a field assembled system where each piece is lifted individually rather than multiple pieces lifted as an assembly. The two main components are the horizontal rail and the vertical rails. The 6″ deep channel horizontals are around 30 feet in length and weigh around 80 lbs. per member; light enough for two people to lift. The vertical hat channels are around 11 feet in length and weigh 13 pounds per member; light enough for a single person to lift.
Q: Nice presentation – can we get more information on the wheeled cart used to install modules in Nevada?
A: Thank you! We would be happy to send you more information on our QuikCart.
Q: What happens when the CIP pads move around due to frost?
A: The CIP rack is limited to string sizes that can be supported by two ballasted foundations. We do not allow for more than two ballasted foundations to support one rack in order to account for settlement issues. We have installed our racks on two ballasted foundations at our facility and then lifted our foundation up with a forklift so that the rack was at a 20% slope. All components and fasteners were structurally acceptable after the slope was introduced into the racks. With only two foundations, although the slope may change if one should move, the plane of the racks remains.
Q: How is the grounding of racking system accomplished?
A: The racking system itself is a completely bonded and conductive system with bonding throughout created by hardware attachment points at different connection areas through the rack. The module is bonded to the racking system by a direct bolt attachment where the nut and bolt are both serrated to dig into the frame of the module to create the bond. This eliminates any additional steps to bond the module to the racking system.
Q: We have a site that needs 2.5MW of fixed panels. Do you help evaluate layouts to minimize space needs? Also compare to trackers that way?
A: Yes, we can help you with that. We have layout capabilities to determine proper row spacing based on the design of the system. We can also do a comparison analysis of trackers versus fixed in terms of ground coverage ratio and land usage.
Q: Do you also provide ground mounted smaller residential racking systems?
A: Unfortunately, we do not at this time. Our minimum project size for our fixed tilt systems is 500kW.
Q: What would be the cost advantage between precast and CIP solution offered?
A: The main cost advantage when comparing these two systems lies in the transportation costs for shipping large pre-cast ballast blocks over the road. There is also a cost savings realized on site where the large pre-cast blocks need to be staged before installation and then moved into final position using heavy lifting equipment. This all depends on the project site and location. Due to these factors, the added cost of the cast in place form is more than made up for in the cost savings on logistics. At SFR we offer both a pre-cast and cast in place system. We can provide you an analysis and quote detailing both options and help you decide which makes the most sense for your project.
Q: Are you guys operating in Western Canada?
A: We can provide our racking and services to Western Canada. We have over 500MW’s installed in Ontario and have manufacturing set up in Ontario as well.
Q: Is Solar FlexRack’s market primarily utility-scale now and ground mounted solutions? Is it cost effective for SFR to pursue roof mount projects? Has SFR permitted any roof mounted ballasted systems in California?
A: Yes, Solar FlexRack’s market is primarily utility and commercial scale ground mount and tracking systems. We do not offer a roof mount product at this time.
Q: How would you approach small projects 200-300 kW? Is Geotech necessary for a small site?
A: We typically do not quote smaller projects, but we have in the past if there is more than just one project in the pipeline or for other reasons that make sense for both parties. If we were to do a project of this size, it would need to be determined based on the project location if a Geotech made sense or not. Without a Geotech, we would design a worst-case scenario foundation, which would add cost. Our Geotechnical Engineer would inspect the site location and make a recommendation based on soils in the area as to what that best approach might be in this case.
Q: If you have a site that is known for having rocking conditions, shallow bedrock, do you recommend a CIP ballasted system? Do the additional costs of refusals with pier installation justify the upcharge with using the ballasted system?
A: It depends on just how unforgiving the conditions are at the site. We typically will review the Geotech report and conduct pull testing to determine the optimal foundation design. Typically, our testing will include a few different post types for sites that are rocky. We may test a drill and grout system, helical pier, or a drill and drive solution to determine what will work best for the site. There are sites where the additional cost of working through the refusals does justify looking at a cast in place, ballasted system.
Q: What is the capacity of your CIP?
A: The CIP ballast forms are sized for the site-specific wind, snow, and seismic loads. We have designed for areas in MA up to 120mph wind loads per ASCE 7-05 with 50 psf snow.
Q: Have you had a time study done on the full install of any of your racking systems?
A: Yes we have! We have had third party time studies done on our fixed tilt racking systems by The Industrial Time Study Institute Inc. Contact us if you would like more information on the results of the time study.
Q: Do you guys offer installation services in other countries?
At this time the only countries we offer installation services to are the U.S. and Canada.