The worth of engineering: Methods to optimize solar designs at each part of a challenge


By Contributing Author July 11, 2022

While “project optimization” and “value engineering” are usually regarded as one thing that happens as a single effort through the part when a challenge is about 30 p.c designed, it’s truly a steady course of that begins a lot earlier, and stretches a lot additional, than that temporary 30 p.c design level.

Optimization and worth engineering needs to be seen as a part of a holistic mindset that’s at all times targeted on lowering prices and rising worth. As the nineteenth century American civil engineer Arthur Mellen Wellington as soon as stated, “an engineer can do for a dollar what any fool can do for two.” It is that this mindset that may and will pervade every facet of a solar challenge — from begin to end — to make sure every challenge is as helpful and price efficient as attainable.

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We have listed right here the first methods builders and engineering, procurement and development corporations (EPCs) can optimize solar initiatives by worth engineering throughout a number of key phases utilizing examples from current initiatives in upstate New York.

Phase 1: Reduce extra gear throughout utility interconnect utility

One of the primary methods to cut back prices when creating the designs for a utility interconnect utility is to cut back extra gear. As context, nearly all of solar challenge designs begin by copying a earlier challenge in order that the location structure drawings and single line diagrams could be shortly generated to make the utility interconnect utility and get the challenge into the approval queue in probably the most cost-effective method. During this part, builders typically don’t cease to ponder why some gear could or might not be included within the preliminary designs as a result of they’re targeted totally on continuing with the interconnect utility as shortly as attainable. The one who accomplished the designs for the earlier challenge, which the present challenge designs are primarily based off of, won’t have recognized why particular gear was or was not included both, however they moved ahead with the designs as a result of they have been authorized and inside funds.

For instance, for ground-mount initiatives with overhead distribution strains on the level of frequent coupling to the utility, now we have been seeing varied excesses in gear, equivalent to:

  • Sets of surge arresters on each pole
  • Extra disconnect switches
  • Duplicate metering

Oftentimes, when there’s a pole-mounted Gang-Operated Air Break (GOAB) swap positioned two poles down from a hot-stick (stay line instrument) operated disconnect swap, it’s unlikely that anybody will ever use the hot-stick operated swap since they’ll simply open and lock on the GOAB from the bottom.

Castillo Engineering diagramDiagram 1. Overhead distribution strains on the level of frequent coupling to the utility positioned in upstate New York.

Beyond that incontrovertible fact that the stay line instruments in these conditions are extreme and add pointless further prices, stay line instruments are additionally unwieldy due to their size, issue to make use of and are topic to OSHA-required testing each two years, which ends up in additional avoidable prices.

Although a few of these extreme units should not huge ticket gadgets, if they’re functionally redundant or received’t be used in any way, then there is no such thing as a motive to spend cash on them that would in any other case be saved or invested in different points of the challenge. Always attempt to attenuate the invoice of supplies (BOM) to finish the job in probably the most cost-effective method attainable.

Phase 2: Eliminate redundancies throughout gear procurement

Another key technique for lowering prices on a solar challenge is to completely evaluate and remove any redundancies through the gear procurement part.

For instance, in a collection of 5 completely different 5-MW initiatives in upstate New York for a shopper of ours, we have been engaged to execute the engineering after the interconnect approval was acquired. Our shopper’s first process for us was to touch upon the steadiness of plant gear quotes that they’d acquired. The gadgets that have been reviewed included:

  • 15-kV recloser
  • Grounding transformer
  • Combiner bins
  • Pole-mounted metering cluster
  • Pole-mounted GOAB swap
  • Pole-mounted fuse cutouts
  • Data acquisition system
  • Aux power transformer and panel
  • Surge arresters
  • Secondary metering

After conducting an intensive evaluate and evaluation, we have been capable of establish {hardware} financial savings of over $200,000 for every of the 5 initiatives. The majority of those financial savings have been derived by the elimination of redundant gear and the discount of overspecifications on different gear.

Phase 3: Mitigate cable value, contemplating future O&M prices, throughout design

An important facet of the design part is with the ability to work with the contractor early on to find out gear preferences, as this could considerably scale back future operations and upkeep (O&M) prices.

For instance, deciphering the utmost desired measurement of cable to be run is essential, equivalent to 800-kcmil most single aluminum conductor and 600-kcmil most twin aluminum conductors. Other typical questions that affect the design, and thereby the challenge prices, are:

  • The most popular places of the combiner bins
  • Whether the combiner bins might be supplied with pre-installed Unistrut mounting rails
  • What the specified car entry widths and turn-around areas are.

Examining the trade-offs in combiner field places is a multi-variable effort as a result of ease of entry for O&M work may come on the expense of both longer string conductors or combiner field output conductors. Also, if trenching is being utilized, that value must be factored in as effectively.

With the worth of supplies drastically rising over the past 12 months, now we have seen some shoppers begin to contemplate loosening their voltage drop standards as a result of the diminished losses from bigger cables now have a considerably longer payback, whereas others are sustaining their strict voltage drop standards. Typical standards might be to focus on a 1.5 p.c common dc voltage drop, with a worst case allowable dc voltage drop of two p.c, which could be a actual problem for uniquely formed solar websites.

Diagram 2. Initial challenge design in inexperienced (left) and contractor really useful design in pink (proper) for a solar tracker challenge in upstate New York. The desk under exhibits the drastic improve in size for the copper string wiring and the rise in common dc voltage drop.

Diagram 2 is an instance from one in all our current initiatives in upstate New York. It exhibits combiner field places and trenching as initially designed to optimize cable lengths, sizes and voltage drop in inexperienced, and contractor really useful places to attenuate trenching in pink.

While the contractor suggestions decrease trenching and the size of aluminum combiner field output conductors and conduit, the desk under signifies the drastic improve in size for the copper string wiring, together with a rise in common dc voltage drop from 1.5 p.c to 1.7 p.c.

castillo engineering table

The last design that Castillo Engineering produced required a number of iterations with a view to discover the optimum compromise between the unique design and the contractor really useful design.

A large number of things should be thought of when designing a solar challenge, together with future O&M prices. Recommendations for gear, equivalent to conductors, can range significantly. It is pertinent to carry out an intensive evaluation to find out the professionals and cons of every design with a view to discover the optimum answer.

Phase 4: Reduce time, prices with flexibility throughout prolonged post-design

Developer and EPC shoppers typically can deliver solar initiatives to design and engineering corporations which have difficult design schedules. In these conditions, Phases 1 by 3 are mixed and sometimes result in fourth part — prolonged post-design. Adaptability in these conditions is paramount to maintain prices down and meet tight deadlines.

For instance, we not too long ago acquired a 6.6-MW solar tracker challenge in New York that used string inverters and had a difficult design schedule. The shopper submitted the essential challenge data to us on a Tuesday and requested that we generate a 60 p.c design in accordance with their requirements in a single week.

Our customary contract schedule is 4 weeks to supply a 90 p.c submittal, so a major quantity of design work was compressed, and it was hampered by not having a CAD file for a structure drawing or any racking data. This shouldn’t be the primary time that now we have proceeded primarily based on PDFs, and we have been capable of make the most of the suitable racking particulars from our challenge library to submit the 60 p.c set in a single week, as requested.

There have been then a number of iterations of the 90 p.c design, as we acquired varied units of shopper and proprietor feedback along with a racking structure change and varied modifications in PV module picks as a result of availability and price. Some feedback have been small in scale, such because the elimination of two strings on a half desk, which was later modified to the unique design intent, returning the 2 eliminated strings again into the array. Most of those design iterations have been requested with a one-day turnaround time, two days most. Issue for development (IFC) drawings have been lastly issued to fulfill the schedule with some gear nonetheless “on hold” from the shortage of receiving store drawings. However, regardless of these vital challenges, this challenge is being efficiently executed with a minimal quantity of contractor requests for data (RFIs).

Bottom line

At Castillo Engineering, now we have discovered over 25 years (and over 300 utility-scale solar initiatives), that it’s a uncommon challenge certainly that proceeds from the 30 p.c preliminary design to the 60 p.c design to the 90 p.c design (problem for allow) after which to the 100% design (problem for development) with just one set of feedback to include at every stage. The current provide chain points have additionally created a big improve in materials substitutions being requested effectively into the development part merely as a result of lack of availability of the popular gear.

At the tip of the day, with the ability to acknowledge and implement alternatives for optimization at virtually any stage of the challenge by main mechanical completion, paired with a excessive stage of flexibility, are key to mitigating prices and maximizing challenge worth.

Joe Jancauskas is a senior electrical engineer at Castillo Engineering, bringing 30 years of engineering expertise, primarily working for utilities and solar EPCs. Joe holds a bachelor’s diploma in electrical engineering and a grasp’s in engineering administration. John Cruz is a solar engineer at Castillo Engineering. He has a bachelor’s diploma in electrical engineering from the New Jersey Institute of Technology.

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Tags: industrial and industrial, utility-scale


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