Considerations for integrating solar power in new construction

July 24, 2019

[1]HORIZONS
Suvi Sharma

As solar energy becomes increasingly mainstream, thoughtful consideration of how best to integrate this photovoltaic (PV) technology into new construction has long-term implications for project success and building owner and occupant satisfaction. Architects, builders, and specifiers have a critical role to play in ensuring new structures incorporate quality PV products. Owners and builders’ priorities as they undergo the process of evaluating solar products for deployment in new structures must be the selection of efficient, affordable, and attractive PV technology.

Construction professionals, property owners, and communities are increasingly interested in lowering their carbon footprint, and building high-performance, net zero-energy structures. For years, builders and architects have visualized the construction of self-sustaining buildings that generate their own power. Today, the concept of a solar-powered building is neither remote nor unachievable. Thanks to recent advancements, architects, engineers, developers, and builders can deploy solar everywhere—on rooftops, building façades, and even in windows. The dream of having buildings performing as their own clean power plants and generating their own clean energy is being realized. For example, a 900-kW PV array deployed atop two buildings at Cornell Tech in New York City advance the institutional goal of achieving a net zero-energy campus by delivering outstanding performance, affordability, attractive aesthetics, and high efficiency and energy yield. A new 1.72-MW solar system deployed at an IKEA outlet near San Antonio, Texas, produces 2.5 million kWh of electricity annually for the store, the equivalent of providing electricity for 280 homes (~ to reducing 1868 tons of carbon dioxide [CO2] and equal to eliminating emissions from 400 cars).

Increased PV deployment is being driven by customer demand, the desire to reduce impacts of CO2 emissions, and attractive economics. Solar deployment has been growing rapidly in the United States, with zero prospect of tapering off.

Six years ago, the United States had less than 1 GW of deployed solar generation. Today, it has cumulatively more than 64 GW of deployed solar, and there is 108 GW of PV capacity worldwide.

Images courtesy Solaria[2]
Images courtesy Solaria

New standards and incentives are helping boost solar deployment in the United States. Last year, California instituted a new building code requiring all new homes constructed after January 1, 2020, to be outfitted with solar. Cities in Arizona, Florida, and Massachusetts have established similar requirements. Watertown in Massachusetts requires solar deployment on all new commercial buildings larger than 929 m2 (10,000 sf) and all new residential structures of 10 or more units. Other states and municipalities will likely follow suit, rolling out similar policies in the years to come, as jurisdictions make increasingly ambitious commitments to renewable energy adoption.

New residential and commercial construction with solar is increasing. Solar suppliers and electrical contractors are supporting the integration of PV into new design/build. Every major electrical supply house in the nation is providing a complete line of electrical management systems to support solar energy integration. Residential, commercial, and utility-grid interconnect of solar generators is widely permitted.

The process of utility-grid connection works as follows: solar installation companies typically submit interconnect applications on behalf of the utility account holder. To process the permit, the system owner’s utility requires information about a property’s electricity usage and system specifics (e.g. size, equipment, design, generation estimates, and location). Once the utility grants approval, the PV system installation may proceed. Upon completion, both the local government and the customer’s utility company send representatives to examine the system—inspect the inverter, connection at the electrical panel, and functionality. The utility then installs/upgrades a more sophisticated meter that tracks solar electricity exports to the grid, enabling the system owner to leverage the utility’s net-metering incentive. Following inspection and meter upgrade, the final step in interconnection is the granting of permission to operate (PTO). Official PTO documentation notifies the owner they can officially turn on the solar panel system for electricity generation. Utility-scale installation can be more complex, and frequently require transmission upgrades to the local distribution system. These costs are usually borne by the solar project developer.

Solar energy is fully embedded in Article 690 of the National Electrical Code (NEC) that provides definitions and guidelines for solar PV electrical energy systems, array circuit(s), inverter(s), and charge controller(s) for design, deployment, and permitting.

Almost all of the solar PV technology deployed today is in the form of rooftop panels installed in essentially the same manner as those retrofitted to existing structures. Mounts/racking are installed on existing roofs, solar panels are fixed to the racks, and the remaining components (inverter, wiring, interconnections) are incorporated to complete the solar energy system.

When the roof is invisible because of parapets, height, or other factors, this tried-and-true method of deployment makes both environmental and economic sense. However, when the PV system being deployed is more visible, building architects and owners are demanding alternatives that add, rather than detract, from the aesthetic look of the new building.

These alternatives start with deploying more attractive and efficient solar panels. PV panel grid lines, busbars, and the circuitry—historically associated with conventional solar panels—result in visually calling undue attention to internal electrical components. That distinctive conventional solar panel ‘look’ is inconsistent with the aesthetic aims associated with many modern buildings’ materials, surfaces, and specifications.

More efficient panels—devoting almost all of their surface area to generating electricity—are now available on the market. Advances in PV panel manufacturing have transformed solar cells from discrete components into aesthetic monolithic structures without inactive unattractive spacing (e.g. busbars) between cells. Not only do these advances make solar panels more efficient by increasing their energy yield, but also present a more attractive and consistent appearance pleasing to the eye. For example, some solar panels on the market offer a uniform look without visible busbars, circuitry, or gridlines.

In many instances, when designing and developing new structures, specifying all-black panels and thoughtfully integrating proven mounting techniques enables builders to meet and exceed requirements for attractive aesthetics and higher efficiency. High-efficiency solar panels are suitable for space-constrained applications in residential and commercial construction. A key benefit of deploying high-efficiency solar panels is that this cost-competitive approach empowers builders to successfully achieve both their environmental and economic goals.

Achieving net zero-energy at Cornell Tech’s campus in New York City required high-performance, 900-kW photovoltaic (PV) solar panels on a space-constrained urban rooftop.[3]
Achieving net zero-energy at Cornell Tech’s campus in New York City required high-performance, 900-kW photovoltaic (PV) solar panels on a space-constrained urban rooftop.

However, technologists, architects, and builders’ vision of attractive integration of PV into new construction does not have to end with more attractive rooftop solar panels. In fact, deploying solar on the roof is only the beginning. Building integrated PV (BIPV) and architectural solar—embedding PV in building façades—is an area showing tremendous promise.

Rather than mounting a solar panel to a structure’s rooftop, BIPV adapts a typical building component, such as a window, spandrel panel, or other cladding, to produce electricity. If a BIPV component were to be removed from a structure, the resulting gap in the façade would be filled with a substitute building material (e.g. concrete).

BIPV is most suitable for buildings with a high proportion of roof to glazing, such as multistory commercial structure, and for specialty applications like greenhouses. In fact, the only way many commercial buildings will be able to achieve net zero-energy status—an objective pursued by an increasing number of architects, owners, and developers—is to incorporate BIPV into their construction.

The author’s experience shows both the challenges and the opportunities of BIPV. The author’s firm introduced a transparent glass material in 2017 with an almost invisible electric generation capability. Mass-produced PV cells were sliced into thin strips, and embedded between glass layers in a window. Thanks to the human visual perception, the PV is not obvious when looking through the window.

This offers building owners and occupants’ several benefits in addition to electric generation: the PV strips absorb light hitting the building’s windows, reducing the solar heat gain coefficient (SHGC), the building’s internal temperature, in the warmer months, and retaining warmth in the cooler months, thereby lowering air-conditioning/heating costs and increasing comfort.

However, commercial uptake of this material has been limited for reasons worth expanding on, in part because each one is or will be addressed in ways relevant to specifiers.

Multiple stakeholders

The success of BIPV relies heavily on collaboration by building owners, architects, engineers, construction companies, glaziers, building envelope suppliers, and civil electrical contractors. The required level of coordination can be daunting.

Limited supply chain

BIPV is low volume and therefore difficult to source, and currently somewhat expensive.

Fabrication and construction skills

Installing BIPV, including wiring, glazing, and/or spandrels to a building power system, has construction implications that introduce uncertainty until additional experience and expertise are acquired. (A fact further preventing greater acquisition of that experience and expertise).

Warranties and support

The industry’s experience with solar panel reliability is high, and the effort required to physically swap out a panel is relatively low. However, BIPV introduces an entirely new set of considerations, since glazing, cladding, and other components add layers of complexity.

Full-size PV cells are cut into thin strips and then assembled into high-density sub-strings to eliminate gaps and busbars. This ensures PV is not obvious to onlookers.[4]
Full-size PV cells are cut into thin strips and then assembled into high-density sub-strings to eliminate gaps and busbars. This ensures PV is not obvious to onlookers.

As is apparent, there is a certain ‘chicken-and-egg’ quality to BIPV. Greater volume requires additional experience and expertise for developers, builders, contractors, and owners, which is not (yet) widely available. Increased demand is dependent on garnering greater expertise in this arena.

When the author’s company experienced this dilemma, it responded by supplying the technology to manufacturers of glass, commercial window, and cladding systems. The belief is once BIPV is more widely offered by established companies, the concerns enumerated above will vanish.

To truly mainstream BIPV and net zero-energy buildings, architects and developers must design structures with solar PV from the beginning, rather than apply it as an afterthought to the structure. This will necessitate looking holistically at a new project, determining prior to commencement of construction what a building’s energy consumption will be, as well as its carbon footprint and ecological impacts. Armed with these insights and knowledge, there are increased opportunities to design and build world-class, aesthetic buildings with solar PV in their skins.

Products offering the greatest energy yield affordably and efficiently will prove to be the perennial winners in a competitive market. Reputable solar manufacturers offer 25-year warranties on power, performance, and workmanship of solar panels. Increasingly better rates of cell and panel efficiency continue to be drivers when it comes to lasting success.

The industry is on the threshold of a new era in design and construction of homes and commercial structures. There will be demand for solar-outfitted rooftops, windows, walls, and building façades, especially since many commercial buildings do not have a practical way of offsetting energy costs due to the constraints posed by limited rooftop space. Structures offer vast potential for generating clean electricity, while providing tremendous cost savings. There are significant opportunities to shift the operational power equation from energy net losses to net gains.

By deploying solar, developers, construction professionals, and building owners will increasingly be transforming structures into highly efficient generating assets with an aesthetically pleasing look.

Specifiers will be seeing increased demand for high-efficiency rooftop solar panels, as well as architecturally aesthetic PV embedded into structures. Undoubtedly, communities and municipalities will increasingly be requiring commercial structures that are ‘green’, and meet sustainability standards. Urban planners will be looking to specifiers for the latest in PV and energy storage technologies.

Cornell Tech’s net zero-energy campus in New York City, outfitted with PV panels, serves as an exemplar for rooftop solar power on new structures being designed and built through the United States. The new Kirin Beer facility in Yokohama, Japan, is an example of how beautiful BIPV can be deployed in a new building.

Solar innovations have the potential to drive global transformations in architecture, design, and construction to help meet the sustainability goals of today’s—and future—generations. The solar industry is geared up to respond. It promises to be an exciting time. The sky is the limit.

Suvi Sharma is CEO of Solaria Corporation, headquartered in Oakland, California. He can be reached at sdevico@solaria.com[5].

Endnotes:
  1. [Image]: https://www.constructionspecifier.com/wp-content/uploads/2019/07/Suvi-Sharma-CEO-Solaria-hi-res.jpg
  2. [Image]: https://www.constructionspecifier.com/wp-content/uploads/2019/07/Cornell-Tech-BEAUTY-shot.jpg
  3. [Image]: https://www.constructionspecifier.com/wp-content/uploads/2019/07/Cornell-NYC-17-09-3589.jpg
  4. [Image]: https://www.constructionspecifier.com/wp-content/uploads/2019/07/STRIPS.jpg
  5. sdevico@solaria.com: mailto:sdevico@solaria.com

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