Solar project logistics: Calculating the value of an efficient supply chain

solar inverter supply chain

What is a supply chain? It is the flow of all components that go into a given product, and then the flow of that product from its manufacturing origin to its end destination. In a global economy (yes, there still is one, despite Trump’s best efforts) the path from cradle to application can get wildly complex. Inverters are a great example. Modern inverters have thousands of components, integrated into sub-assemblies and then into the inverter product. Sometimes this is happening countries and oceans away from the final point of installation.

As inverters become more homogenous in their basic functions and reliability, finer elements of performance will define the strengths and weaknesses of inverter suppliers. Each supplier’s own ‘supply chain’ is one of those competitive performance variables that buyers and system designers need to consider.

RELATED: How to maximize large-scale PV site value with string design

Why?

An optimized supply chain is valuable to project owners for all of the inherent benefits of efficiency:

  • Costs will likely be lower
  • Lead times will likely be shorter
  • Fewer steps from A to Z means less risk of errors occurring
  • Adjustments will be easier to make on the fly

As it relates to inverter suppliers specifically, developers and EPCs should consider the following.

1. Follow the path of the inverter in reverse, from PV application location, upstream to the site of manufacture.

Does the path make sense? Consider how many stops and warehouses are involved because every stop and transition slathers on another layer of risk and cost.

Beyond the physical transition from place to place, how many changes of ownership are involved in the movement of goods? Is a third-party warehouse used, or a third-party distributor required? Every hand-off means transition of ownership (title and/or process) and usually means added cost and markup by each party. The end owner of the inverter pays for all this, so make sure whether or not you are paying for added risk or added value.

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2. Product line strategy – the higher quality inverter could come at a better price point depending on the product line and the supply chain.

How many options, variables and models are you dealing with? Sometimes too many variables means an increased risk of management mistakes and costs, as well as more overhead to manage more parts. Contrast that with a line of a few feature-rich, flexible product models that work for a variety of applications. This can be easier to manage and is helpful for designers.

Now, will feature-rich options add to costs? Not necessarily because of the economies of scale gained from producing fewer models. A localized inventory is more feasible with fewer products to focus on, leading to shorter lead times and ready-to-go stock and reduced inventory investment. Applications engineering, service and life-cycle support is also easier to manage with fewer products for both buyer and seller.

3. Get a full picture of all variables.

Weigh the pros and cons of a supplier manufacturer versus a third-party contract manufacturer. Consider the proximity of the fulfillment hub to the user and the carriers used (is it FedEx or some random company?). Just remember that a fulfillment hub or “Made in the USA” sticker doesn’t give the full picture. The global center of power electronic component production is Asia. So an inverter fully pieced together in Asia that ships to a U.S. fulfillment hub may actually be the most efficient supply chain you could find.

We will also dive into this in MUCH greater detail in this upcoming free webinar. Sign up here.

Utility-Scale String Design

Wed, Jun 20, 2018 2:00 PM EDT

When designing a large site one consideration is String or Central. Both have well defined benefits. Historically, the large utility-scale sites have mainly relied upon central inverters. Now a third option, the Virtual Central, is paving the way for string inverters into this space. In this webinar, we will discuss the benefits and disadvantages to both the distributed and centralized string architectures and how the design choice affects installers, developers and site owners. Sign up here.

— Solar Builder magazine

Power factor boost: Make sure to maximize revenue in design, data monitoring

inverer power factor

Remember the Seinfeld episode where the rental car company took Jerry’s reservation, but still didn’t have a car for him“You know how to take the reservation, you just don’t know how to hold the reservation. And that’s really the most important part: the holding. Anybody can just take them.”

That’s a way to think about monitoring performance of a solar site. (Just go with me here) Anyone can just monitor data, but the key is knowing what to do with it – being proactive versus reactive. Here’s two considerations for being proactive involving inverter selection.

Factoring for power factor

Utility-scale sites often come with reactive power requirements, which usually means reducing the real power produced to provide reactive power support. Because of this, be sure to check the power factor or Max AC Output Power of inverters you spec.

“When you reduce active power, you’re not getting paid at what you designed the system for,” says Sarah Ozga, product manager at CPS America. “We want customers to get paid for the nameplate rating of the inverter and not get dinged for reactive power requirements.”

CPS inverters, for example, come with kVA overhead and will supply 100 percent active power while accommodating reactive power requirements. For a 100-kW inverter, this is listed as 100 kW / 111 kVA at PF greater than 0.9 and 125 kW / 132 kVA at PF greater than 0.95 for the 125-kW inverter. Let’s play out some scenarios.

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“If we had a 100 kW/111 kVA or our 125 kW/132 kVA rated inverter and the utility company said we need to run at .95 power factor (PF) we could do this without sacrificing real power (kW),” Ozga says. “For example, if we have enough PV power coming in from the array to produce at max capability on the 125kW/132kVA inverter we would be producing 125kW active power and the apparent power would be 132kVA.”

But what if this overhead wasn’t built into the inverters? If the inverter’s apparent power was capped at 125 kVA, at 0.95 power factor (PF), it would be producing 118.75 kW active power. This is about 7 kW less than it could be producing if it had overhead capacity.

“That’s not real significant for a single inverter but these inverters are generally installed in a multi-MW system,” Ozga notes. “So for a 10 MW site that would be 570 kW, which is a significant loss of power.”

Maximize revenue

Over the life of a system, discovering issues early and fixing them quickly can make a huge difference in site performance and, what everyone is here for, revenue. If an inverter goes down or performance is low, make sure the manufacturer is able to remotely troubleshoot, push updates or make setting changes to the inverters without needing to visit the site, like CPS Ameri-ca can within its Flex Gateway. This gets the inverters back up and performing as it should fast-er and cheaper.

“Whether a company is managing its own data or is using a third party monitoring package it is important for the data to be actively monitored,” Ozga says. “That doesn’t mean someone needs to sit in front a computer watching production graphs all day. Set up automated emails/SMS for alarms or warnings for each site that is managed. These warnings could alert you when an inverter is not performing as expected.”

We will also dive into this in MUCH greater detail in this upcoming free webinar. Sign up here.

Utility-Scale String Design

Wed, Jun 20, 2018 2:00 PM EDT

When designing a large site one consideration is String or Central. Both have well defined benefits. Historically, the large utility-scale sites have mainly relied upon central inverters. Now a third option, the Virtual Central, is paving the way for string inverters into this space. In this webinar, we will discuss the benefits and disadvantages to both the distributed and centralized string architectures and how the design choice affects installers, developers and site owners. Sign up here.

— Solar Builder magazine

2016 Editor’s Choice Projects of the Year: Community Spirit

beardWe say it every year: When it comes to solar projects, we are all winners.

We already announced the winners of our 2016 Project of the Year vote, but we at Solar Builder liked a bunch of the other submissions too. Welcome to the first in our series of Editor’s Choice winners! These are projects that
didn’t garner the most votes from readers but we felt were still pretty darn cool too.

Editor’s Choice: Solving Space Limitations

 Town of Stafford

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Challenges: Building this PV system on a rocky, steep terrain required special drillers just to install the piles. Some boulders pulled out were bigger than a pickup truck. Developer Standard Solar did a formal study and used innovative smart inverter capabilities to integrate to the grid according to ES’s requirements. The landfill part of the project was unique in that all electrical wiring/conduit and racking foundations had to remain above grade so as to not penetrate or disturb the cap layer. Standard had to run the inverter output feeders in conduit down a very steep (approximately 40 percent grade) section of the cap in order to reach the equipment pad. Innovation: This is one of the first virtual net metered projects approved in Connecticut, and it offsets 100 percent of the town’s load, making the whole town net zero. It supports mostly schools and other community loads.

Town-of-Stafford-landfill-solarLocation: Stafford, Conn.

Size: 3.45 MW

Developer: Standard Solar

Contractor: Electrical Contractors and Maine Drilling and Blasting

Modules: Hyundai Heavy Industries

Inverters: Chint Power Systems

Mounting: GameChange Solar and DCE Solar


 

Cedar Falls Utilities “Simple Solar” Initiative

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Cedar Falls Utilities (CFU) launched its “Simple Solar” community initiative to meet a growing demand for clean energy, while offering flexibility around participation in the project. CFU gave its customers the opportunity to pre-subscribe for the solar energy by making an upfront payment. These payments gave customers access to a portion of the energy that the array will produce — an amount by which their energy bills will be reduced — and the more customers who participated, the lower their cost to participate. This approach proved demand and interest among customers, drove the size of array built and created a mechanism where a customer could apply their energy savings to another home if they decide to move. Interest drove the solar unit price from $399 to $270. This became the largest community solar project in the state.

Location: Cedar Falls, Iowa

Size: 1.987 MW

Developer: RER Energy

Contractor: SunLink PowerCare

Modules: Hanwha

Inverters: Yaskawa-Solectria

Mounting: SunLink

 

— Solar Builder magazine