How a transparent, modern grid properly values solar, DER

grid modernization with solar

Much of our Attack the Tariff campaign is focused on market-based innovations that improve the upfront costs and long-term value for a variety of solar projects. But state-based solutions and local movements often make the biggest impact. In a series of white papers this year, the Solar Energy Industries Association (SEIA) made a solid case for how regulators and utilities could lay the ground work for a more modern-day grid that takes better advantage of distributed energy resources.

“When states develop fair compensation mechanisms for distributed energy resources (DER), the result is a modern electric grid that better serves the needs of all its customers,” said Sean Gallagher, SEIA’s vice president of state affairs. “The case studies highlighted in our report can serve as a model for other states interested in grid modernization and the economic benefits that result.”

We recommend reading the whole thing. Our big takeaway is just how imperative it is for utilities to be more transparent with their data, forecasts and calculations. We need to get more voices in the room to offer solutions. What locations in an area need which specific upgrades? For what time of year? For what time of day?

Transparency

We all already know utility transparency is an issue, but when the possibilities for grid modernization are laid out as SEIA has done in this series, the lack of transparency seems more inexcusable than ever.

Our favorite concept from the report came in part four, Getting More Granular: How Value of Location and Time May Change Compensation for Distributed Energy Resources.

Locational value can be used to guide resources to high value locations. Utilities can create, and should publish maps showing the specific locations of any needs on the distribution system, the specific grid constraints to avoid the need (e.g., high loads during hot late summer afternoons), and the value of the avoidance in terms of dollars per amount of capacity. If a developer knows in advance that there will be a utility solicitation for the identified needs, it can begin seeking customers or project sites in anticipation of the opportunity to bid in its projects.

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The report continues in that section to lay out a basis for compensation:

In addition to competitive utility solicitations, there are alternative means of providing targeted tariffs, programs or incentives to drive DER to locations to meet identified needs. If identified needs are too small or have too short of a lead time to be met through a competitive solicitation, the utility could have a tariff- or program-based mechanism that can step in on short notice.

For example, voltage issues are often very isolated and managed with small utility investments. However, smart inverters are increasingly being deployed widely and can be used to provide voltage management services in the locations where a utility has challenges managing voltage within an acceptable range.

In addition, tariffs enable customers of all stripes to adopt solar and other DER, which delivers the generalized grid benefits we discuss, but also ensures that a state’s clean energy market grows equitably in a manner that distributes the social, environmental, and economic benefits to all ratepayers. This is an emerging topic and it is expected that California’s Integrated Distributed Energy Resources proceeding will explore non-solicitation based sourcing mechanisms.

So, there needs to be more transparency for developers and engineers to jump in and propose solutions, but there also needs to be more general transparency for the public to better understand how electricity gets to their house, what exactly it costs, and what alternatives could look like. Each small decision is super complicated, but zooming back out and considering the broad strokes from the point of view of an actual home owner would be revealing.

Changing incentives

In part five, which considers DER and non-wires solutions, SEIA makes the case that enhanced distribution system planning should incorporate the following key features:

• DER growth scenarios to inform grid planners where organic DER growth can be expected and where incremental DER deployment is needed.
• Hosting capacity analyses to determine DER hosting capacity limits on the distribution system to inform grid planners where additional investments may be needed to enable higher penetrations of DER.
• A methodology for fully valuing distributed energy resources to ensure proper price signals
• A transparent evaluation process by which NWS can be measured against traditional utility investments to determine the best investment for ratepayers.

Distribution utilities often make money on the construction of substations and other major capital projects. By avoiding those expenditures with solar or other DER, utilities would lose revenue opportunities, which is obviously a disincentive. This is why in California and New York, both states leading the way into a new era of transparency and collaboration, regulators have created compensation mechanisms to remove this potential bias.

This approach has allowed Southern California Edison to acquire about 260 MW of location-specific DER, 50 MW of which is distributed solar. In New York, the Public Service Commission agreed to defer the construction of a $1.5 billion substation, instead having Con Ed meet the forecasted load with 17 MW of customer-sided solutions and 52 MW of non-traditional utility-sided solutions by mid-2018. The overall budget here was only $200 million, of which only about $69 million was spent. The remaining money will be used to defer additional investments.

Bottom line, this series illustrates that if you started the grid from scratch in 2018, knowing what we know, and with the technology we have, there is just no way you’d arrive at the current arrangement and business model. Having utilities prioritize DER with the same long-term, capital intensive strategizing that they current apply, could be the most impactful U.S. innovation this century.

— Solar Builder magazine

Degrees of Separation: How to mount commercial rooftop PV systems to maximize energy

Ecolibrium EcoFoot system

Ecolibrium EcoFoot system

On commercial rooftops, design trends are all about maximizing energy density. Module selection is a huge factor there, but so are the layout and tilt decisions — figuring out the perfect shape and tilt to mount as many modules as possible without compromising their performance.

Pairing the right racking system with a flat-roof space opens up a world of possible equations. Use a racking system that will position the panels to maximize the energy output, which includes the tilt angle, inter-row spacing and the direction the panels will face. As always, geography matters. For one, the roof’s azimuth, or the direction the pitch faces. For a perfect south-facing system, the azimuth should be 180.

But new systems are tweaking the traditional. East/west systems are becoming popular below the tropic of cancer. Designers are playing more with tilt angles, with the general trend moving toward 5-degree tilt — likely to reduce inter-row shading without compromising the number of modules used or resulting in too much soiling.

“Rooftop energy density is maximized by fitting more panels on the roof using a 5-degree racking system,” said Jonah Coles, product solutions manager, Ecolibrium Solar. “The key to fitting more panels on the roof is to use racking with a small footprint and narrow inter-row spacing. The combination packs in panels, yet the inter-row spacing is wide enough to allow for the working room needed for ease of installation and post-installation maintenance.”

RELATED: Why energy density matters — and three ways to maximize it

But the tilt decision isn’t one-size-fits all. Everest Solar Systems notes tilt angle efficiency correlates to latitude — the higher the latitude often requires a higher tilt. The latitude in Hawaii, for instance, allows a system to be virtually flat, but there needs to be enough tilt to keep the rain from pooling and to keep dust off the modules. Brandon Gwinner, regional sales manager, SunModo, puts that minimum at a 4-degree tilt.

SunModo Sunbeam

“The tilt degree is dependent on the region/location and optimum output based on TSRF,” he says. “The minimal tilt degree racking systems are typically to maximize the number of modules you can get on a roof without your rear post being 8 ft off the roof and to get the most energy density/power density per the project.”

There are also some wind/snow load considerations that can keep tilt below a certain height/tilt degree, as well as parapet walls and billowing of wind. The installer has to find the balance between production and engineering capabilities.

Also, installers looking to maximize production in summer months should consider using lower tilt angles than installers looking to maximize production in winter months. In snowy northern climates, Everest Solar recommends a 10-degree system tilt angle, which is better for shedding snow, plus the wider inter-row spacing allows more room for snow to land without piling up and casting a shadow or covering the modules.

“If you can hit your power goal with a 10-degree system, then 10-degree would be the system of choice. If not, 5-degree racking can enable a successful system when 10-degree wouldn’t fit enough panels to generate enough power,” Coles said.

Commercial installations have significantly more requirements than residential installations, so understanding jurisdictional requirements at the onset of the project will make the process go smoothly. Some states, like Oregon, do not require extra engineering when the tilt is under 18 in. on the back edge of the array, based on a prescriptive path. So, cost analysis vs. ease of permitting is a factor for tilt decisions too.

The inter-row spacing issue

Tilted PV panels cast shadows on the rows of modules behind them, necessitating a gap between rows to minimize the effects of production loss due to shadows cast on panels in anterior module rows. Here are a few ideas to mitigate the impact of this phenomenon on your PV installation via Peter Abou Chacra, engineering consultant, SunModo.

  • Reduce the tilt of your south-facing array. For peak energy production on a per-module basis, PV modules have an ideal incident angle with solar rays emanating from the sun. For some installations, however, it may make sense to reduce the tilt of the modules to a less optimal incident angle. Though this means less production on a per module-basis, it can mean a significant increase in the daily unshaded collection time for the array. This gain in effective collection time can offset the losses caused by a sub-optimal tilt for the module itself. Using software dedicated to modeling and analyzing a system’s performance at a different tilt angle and inter-row spacing should figure out the best path.
  • Locate your system on a south-facing slope. Even a five-degree inclination can have a marked impact on the amount of inter-row spacing required. This can significantly increase the number of modules you can fit in a given area.
  • Consider 3-in-landscape or 4-in-landscape monoslope installations. Coupled with a low tilt, this strategy can reduce inter-row spacing significantly on a given installation since modules on the same structure and slope don’t require significant spacing between them. This can be particularly effective if you can gradually elevate the anterior monoslope PV structures as you work your way north through the site.

— Solar Builder magazine

Solar + Sharing: Connect groups of homeowners, renters via one solar + storage network

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The EnSync Home Energy System includes high-efficiency “LFP” lithium-ion batteries, a Matrix Energy Management system with 9-kWac output capacity, modular energy storage capacity of 9-kWh increments, modular DC-DC converters and the DER Flex Internet of Energy control platform.

Brad Hansen, president and CEO of EnSync Energy Systems, believes solar + storage for the home is still “in the dark ages.” EnSync Energy Systems has built a reputation for deploying high-value distributed energy resources (DERs) in the C&I segment. So why is Hansen discussing residential solar + storage? Well, EnSync has just launched a Home Energy System that will not only address some of the antiquated architecture of current home storage systems but also invent an entirely new project design concept.

At the basic level, the EnSync Home Energy System combines solar, energy storage, power electronics and Internet of Energy control into one platform. It has the advantage of leveraging technology and lessons learned from EnSync’s C&I business to achieve an outcome like lessening thermal stability concerns of repackaged lithium-ion batteries that are often used in a home energy storage applications. Instead, EnSync pairs a residential-scale version of its modular Matrix Energy Management system with thermally resilient lithium-ion batteries and its DER Flex Internet of Energy solution that are all designed to work together.

“Most [current systems] are significantly underpowered and cannot support the entire home if the grid electricity is out, or they have issues disconnecting and reconnecting to the grid during an outage,” Hansen says. “If the home is off-grid, many cannot reliably perform if high inrush currents are created by the start-up of appliances like refrigerators or air conditioners.”

Peer-to-peer exchange

This is the part that could change the sector. The EnSync Home Energy System introduces True Peer-to-Peer energy exchange technology. The goal here is to enable individual residential units in a property to be linked into a network behind the utility meter to provide highly efficient, direct energy exchange between units. Suddenly property developers, property managers and homeowners’ associations can provide seamless and economical transfer of excess energy from any given residence to any other residence in the network with excess demand via EnSync’s DC-Link.

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“The future of the electricity market will be individual homes and building owners operating in a ‘spot market’ for the buying and selling of electricity across a network,” Hansen says. “At EnSync, our mission for the company is simple: the democratization of energy through innovative and economic energy systems. Homeowners and property owners that install our products today do so with the confidence that as the market for energy continues to be radically changed, they are not only prepared for it, but can capitalize on it and profit from it.”

A single residence, multifamily building or entire neighborhood could reduce consumption on the grid and possibly open up a new revenue stream. The sharing of electricity between interconnected residences on a True Peer-to-Peer energy exchange network prioritizes the use of solar generated or stored electricity ahead of that from the utility grid for any residence in the network. The network can also be configured as “non-export,” meaning no excess generation for any unit goes back to the utility grid. This capability is becoming more critical as several states and jurisdictions prohibit or economically penalize energy export.

Additionally, many utilities are in the early stages of implementing time-of-day electricity rates and are already levying punitive demand charges on customers. The evolving rate structures and impact of resident vacancy rates, vacation schedules and time-of-day load profiles frequently make deploying solar generation uneconomical for large portions of property development. Virtual net-metering and virtual peer-to-peer programs are fraught with excessive complexity and administrative overhead.

EnSync will initially target the multi-residential property market for its solution, and then broaden its market presence. At the time of launch, the company had already built a sizable order backlog for the EnSync Home Energy System. The Michaels Development Co. was the first to sign a 20-year PPA to build a solar and energy storage system at the Keahumoa Place affordable housing development, a greenfield project in Hawaii that is expected to complete construction in 2019. Savings from the PPA will finance the construction of a 750-kW PV panel-covered canopy that will simultaneously produce energy and shade the development’s parking lot, as well as a 500-kW hour energy storage system, with individual modules interconnected by the proprietary True Peer-to-Peer DC-Link behind each unit’s utility meter.

“True Peer-to-Peer revolutionizes the economics of solar + storage in residential properties like Keahumoa, by dramatically reducing the negative impacts of vacancy rates, absence during peak generation times, vacation schedules and micro-loading effects within each unit from appliances such as refrigerators and air conditioners,” Hansen says.

— Solar Builder magazine

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