Time to begin to realize a return on your investment.  Once constructed the commissioning process consists of verification, testing, and sometimes rework. 

On your Marks, Get Set,

Time to begin to realize a return on your investment.  Once constructed the commissioning process consists of verification, testing, and sometimes rework.  Ideally the amount of rework is minimal because testing has taken place during construction.  The phrase that “quality is best when designed in” becomes evident when the time for interconnect to the grid finally comes.

Commissioning verifications and tests vary depending on the system configuration and if any pre-commissioning testing is done.   Tests can include looking using thermal imaging to reveal high-resistance connections, amperage tests on tracker motors to test for binding.  Some ground faults are not detected by the inverters, requiring specific testing.   

Make the Plan, Follow the Plan

Meeting the testing requirements of the various permitting agencies and do so in an efficient manner is itself a dauting task.  Retesting, doing the same test to satisfy different agencies can be time consuming, costly, and impact the interconnection commitment.  Best practices are to perform as much testing in advance of the final commissioning activities.

Visual inspections during construction that are completed as each string is completed.  Mechanical (tracker) testing can be done as each block is completed, and so on.  A full list of testing activities, and testing sequences is extensive and can consist of thousands of pages of checklists.  Utility solar construction companies have teams dedicated to the commissioning phase. 

For the journey leading up to commission, we invite you to our blogs on Preliminary Design through Construction at: https://rrccompanies.com/from-concept-to-reality-advancing-your-solar-utility-project/

Now that your Utility Solar Project has been permitted, designed, and fully financed, it’s time to build!

A Ground-Breaking Experience

It is too often the perspective of the engineer that once the drawings are handed over to the constructor, their job is done.  This is rarely the case.  Construction is where reality and the engineering design meet, and reality always wins.  For example, if the Land Survey did not represent the reality of the land, issues with flood control will win.  If the Civil grading plan is based on that same survey then the cost of moving, importing or exporting fill will win.  Issues arising during construction are greatly multiplied with solar utility projects because of the shear scale involved.

One approach is to dial into great-detail the profile of the land, the accuracy of the topo and geological studies.  However, there is a point of diminishing returns.  It’s better to also have a plan to be prepared to address and solve construction problems when they arise.  This is where boots on the ground combined with subject mater experts in the office has found to be the winning combination.

Keeping Your Eye on the Prize

It is a common approach in the oil, gas, pipeline and similar industries to have on-site personnel working with engineers “back at the home office” to address and solve problems when they arise.  Solar project construction also benefits from this approach.  Having one or two people on-site may seem like a cost to avoid, but in comparison to loosing tens of thousands of dollars for each day of construction delay, it is a low-cost investment.  Common stories include reworking the drainage plan due to issues with culverts, or saving on the cost of non-native fill by being smarter about the compaction plan. 

Having an owners-engineer on site helps to ensure construction follows the plan.  Having a construction-engineer on site with home-office backup helps ensure construction problems are resolved quickly.

Knit-One, Purl Two

Another best practice in the construction phase is to build a PV string to completion to serve as a model / template.  Not only does it provide a visual example for workers who may be new to solar construction, it also is the proving ground for things like wiring relief (slack) lengths, wire bend radius, bolt torquing, wiring termination examples, and the like.  The quicker the sample string can be put up and “certified” the quicker materials issues can be uncovered along with having an on-site classroom for the construction crew. 

Because there is so much to the build that is repetitive, having one string completed gives  workers an extra ability to figure out clever ways to be more efficient, either with methods or tools.

Building out the site and seeing it come together is the exciting, albeit mundane part of the project.  Like a marathon runner putting one foot in front of the other, the construction of a solar utility site requires steady forward progress repeating one step after another.

Welcome to day 3 of this short 5-part series following the progression of a utility solar project from idea to interconnection.  Today we touch on Detailed Design. 

Details, Details

“It all works until you get down to the details”, that is what my dad used to say.  Hopefully once you have passed through the Feasibility and Preliminary design phases you won’t come to a point in the Detail Design phase that kills the project (see day #2 for some important helps with that).

Detail design is where drawings, written specifications, etc. specify the final configuration and layout of the equipment, the materials with their quantities,  and very importantly specifying information used during  construction.

It all Looks Good on Paper

I learned early in my engineering career that just because it looks good on paper, it doesn’t mean that that it can be built.  I also learned that sometimes it’s better to let the construction contractor  follow best practice rather than for me to dictate all the details.   

The detail design in a solar project carries the characteristic that a single “error” can have the multiplying effect.  It can impact of thousands of connections, or pieces of equipment.  One example is a simple thing like specifying the type of wire tie-wrap.  One type will last for years, one will degrade in a matter of months.  Since there can be 10,000+ tie wraps, if they embrittle in the sun and need to be replaced, that simple error can lead to large rework and warranty costs.   Specifying a structural bolt that carries with it the need for specific testing can lead to huge costs, not because the bolt won’t do the job, but because the bolt specification requires testing.  The wrong corrosion code for the steel piles is something we have seen.  Imagine finding that once you have 8,000 piles in the ground.  Easily overlooked is specifying cable cuts to minimize the leftover cable on the reel.  This is a “real” problem in cases where splicing is not allowed for underground cables.  If this isn’t considered when the cable is being purchased, the entire construction schedule can stretch out waiting for more cable from the vendor.  Delaying construction is very costly.  The list goes on and on.  

Who’s on First?

One of the difficulties in our industry can be that projects are “piecemealed” together.  One company will do the Feasibility, another Preliminary Design, and yet another Detailed Design.  Because different engineering companies have different ways of doing things, specifically how all the different drawings and specifications work together, having a properly integrated final design package can be a problem.    If one drawing refers to another drawing, or one specification refers to another, someone needs to verify the validity of the reference.

Experience Matters

Successfully completing the Solar Detailed design phase requires experience engineer working with people who have installation and construction experience.  Often companies will send their engineers to the field to get a good dose of reality.  Some companies lean heavily on standardization of design, some are very good at capturing lessons learned and maintaining a knowledge database.  All are good strategies and have their pros and cons.   There is little substitution for experience and not rushing through the Detailed Design Phase.  You can, but likely will pay a big price in the construction phase.

For Day #1 Feasibility, click here

For Day #2 Preliminary Design, click here

Welcome to day 2 of this short 5-part series following the progression of a utility solar project from idea to interconnection.  Today things get real with Preliminary design.  (For Day #1, click here)

Jumping Into The Deep End

Preliminary design is where excitement and dread start to come together.  It’s like that moment when you jump from the high point of a cliff towards the deep lake below.  Things get very real very fast.

Preliminary design in the renewables industry is often termed 30%.  Some clients however ask us to jump from 10% directly to 60% design as the preliminary phase.  Either way the intent is the same.

Roughing it Out

The preliminary design of a solar project is focused on solar collector layouts, locations for major pieces of equipment, roads, storm water control, and the like.  This work primarily involves Civil and Electrical engineers.  It pre-supposes that the Land Survey information and Geotechnical Report are accurate.  Often an initial PV panel layout is used as the starting point.  Sometime other land constraint information must be considered such as environmental zones, setbacks, etc.

Risks and Rewards

What we typically see are requests for preliminary design work that is only focused inside the fence line.  We also see incomplete survey or geotechnical information.  Sometimes this is acceptable, sometimes it presents a lurking risk.

Transmission Lines: Permitting and approvals outside the fence line is overlooked in a large majority of what we see.  A significant risk exists if the transmission line needs to pass through a parcel where access is denied.  Because the T-Line to the utility interconnect substation is typically long, overhead lines are best.  However overhead lines may be denied by local authorities then requiring costly buried lines.   Similarly examining the need for a local substation, or a project substation adjacent to the utility connection substation is often overlooked until later in the design process which can be a costly mistake.

Solar Racking Piles: The information gained from a geotechnical investigation and report is very important for many aspects of the site design, however there is a significant reward (cost savings) that can be realized by adding on-site pile driving and pull-testing.  This is something seldom done at the 30% stage but something that can save hundreds of thousands of dollars in the cost of the steel solar piles.

Boots on the Ground:  We highly recommend sending qualified, multi-disciplined individuals to the site at the 30% design stage whenever possible to visually verify the 10% information and look for things that have been missed.  This is roughly equivalent to sending out an engineering inspector to a commercial building that you might be considering purchasing.   

Some of the stories that come back from these trips never cease to amaze.  Stories like, “we found out that the owner who leased the property also signed a contract to allow cattle to graze” remind us that developing a solar project can be full of surprises. 

Welcome to part 1 of a 5-part series following the progression of a utility solar project from initial idea to pumping out power. 

Lifecycles and Waterfalls

Utility solar projects fall into the general category of the “waterfall” life-cycle.  One phase is started, progresses, then finishes before then the next phase begins.  The waterfall project method is what is traditionally used for construction projects, in contrast to Agile or iterative project life-cycles found in the software or marketing industries.  The development of project management methodology is a relatively recent reality and its’ standardization even more recent.  (ref: A Brief History of Project Management). 

In the utility solar industry, the project management waterfall phases are generally;

• Feasibility (10% design)
• Preliminary Design (30-60% design)
• Detailed Design (90% – IFC)
• Construction
• Commissioning and Start-Up

Feasibility, Risk and Reward

Evaluating a solar project in the feasibility phase is similar to any large land development project in many ways.  Environmental, permitting, financing and construction issues are evaluated alongside projected ROI and these are influenced by revenue projections, short and long-term costs, local and even geo-political forces. 

From the perspective of an engineering company, such as RRC, assisting a developer in the project  feasibility phase is all about providing comprehensive technical and constructability information.

Even when the focus is on these two facets, performing the analysis requires a multidisciplinary approach, especially when it comes to identifying risks  One overlooked factor, such as the downstream impact of flooding, or wide variations in soil properties have the potential to derail or add significant cost.

Optimization in the Feasibility Phase

The value that is most often missed in the feasibility phase is the looking forward to the later life-cycle phases where the detailed engineering occurs.  This type of optimization is typically reserved for later project stages but with large utility solar projects it is important that it is a part of the feasibility phase. 

For example, optimizing for civil grading to reduce tracker costs may actually increase overall project costs.  Optimizing the PV layout may be a matter of being creative with different tracker configurations, pile designs, and the like.   Adding storm water control to minimize local scour around piles may be a better solution than excessive grading and soil stabilization.

All these are factors that may be too costly to refine in the early stages but may have a significant impact down the road.  Having an experienced multi-disciplined team able to look at the potential site and apply their wisdom is a prudent part of the feasibility phase for a solar project.