If you develop, design, or build buildings in Washington, you're going to be hearing a lot more about solar panels in the next year.

Why? A revised State Energy Code will potentially trigger enhanced solar requirements for new construction. Electrical demand will continue to increase with the move towards using electricity for heating and domestic hot water, along with the shift toward electric cars to reduce fossil fuel use. Need and opportunity are converging. Solar is also a way to address our broader carbon-reduction goals while providing a renewable energy source.

Read on to learn the basics of photovoltaics [PVs], how they integrate with buildings, and what's happening with public policy.

What's a Photovoltaic Solar Panel?

Solar panels have been mainstream in America since the 1970s when an oil shortage made everyone aware of our dependency on foreign oil and, to counter public opinion about this dependence, President Carter had solar panels installed on the White House. Since these early installations, system efficiencies, manufacturing processes, and installation techniques have greatly improved.

You've seen a PV panel, but what is it? Photovoltaics is the process of converting light energy into electricity. A PV panel [or module] is made up of layers of solar cells composed of silicon, phosphorus, and boron. Light [photons] from the sun dislodges atoms in the semiconductor material, causing movement of electrons. This movement creates a voltage potential between the negative and positive surfaces in the panel, thus creating electricity. Modules can act alone or grouped to form PV arrays.

The more modules in a PV array the more potential output if the conditions are right. The largest arrays, such as some in California, can exceed 600 Megawatts [MW] of output, enough to supply approximately 100,000 homes on a peak output day.

Ballasted PV installed on Expedia Campus in Seattle

Efficiency Has Improved + May Jump

PV efficiency is the percentage of solar energy a panel converts to electricity—a hot topic in the solar industry. Every year sees incremental increases in efficiency. Most silicon-based PV panels range from 15 to 20% efficiency, and some highly-efficient panels now reach upwards of 23%. The theoretical limit is about 33% for silicon-based panels.

New technologies are pushing this number even higher. Perovskite is the new buzzword as a likely replacement for silicon. Perovskite panels can potentially reach 40-60% efficiency, but with every advantage comes disadvantages. Early perovskite panels were brittle and degraded quickly, however scientists and engineers are now discovering ways around these issues. More work is needed before the new ideas can be implemented at industrial scale, but when they are, the world of solar panels will change.

Rooftop + Building-Integrated Options

PV panels have multiple installation options depending on the structure and substrate. Each has its pros and cons.

• Ballasted. This is the preferred method on flat roofs and is typically the most cost effective. Ballasted panels are set flat on the roof and weighed down to prevent movement in wind or seismic events.
• Elevated Racks. Placing panels into elevated racks has numerous advantages. Panels can clear parapets and rooftop equipment and be angled for greatest sunlight.
• Building Integrated PV [BIPV]. This method involves integrating PV panels on a building's envelope, and includes installing PV on vertical facades, horizontal structures, canopies, or combination of all of them—anywhere that faces the sun. This is an emerging technology that currently involves a cost premium. BIPVs are a growing segment of the market, with more owners and designers exploring how to incorporate them in their buildings.

Impending State Energy Code Changes

The current 2018 Washington State Energy Code, Section C411 [Solar Readiness], requires new buildings to be provisioned for future installation of PV panels. A building under 20 stories needs solar zones totaling at least 40% of the roof area or 20% of the electrical service size, whichever is smaller.

Revising and approving the 2021 WSEC code sits at the industry-committee level now, with the Legislature scheduled to vote on its adoption in Winter 2022/2023. Here's the 2021 Code Review and Adoption Schedule. The current solar proposal would change the PV requirement from solar readiness to a mandatory renewable requirement of 0.5 watts per square foot. See this Preliminary Cost Benefit Analysis for the 2021 Washington State Energy Code [pages 10-11] for additional information.

Tax Incentives

The federal government and State of Washington heavily incentivize PV installation. The federal government offers a tax credit for both residential and commercial installation, and Washington offers a sales tax exemption for systems up to 100kW. In addition, solar generally qualifies for accelerated fully depreciated assets.

Here's more about the Federal Investment Tax Credit [ITC], which currently expires 12/31/2023. This provides a tax credit that can be claimed on corporate income taxes for 26% of the initial cost of a PV system installed in 2022. For 2023 this reduces to 22%, and beyond 2023 it reduces to 10%. Washington sales tax exemptions, which won’t expire until 1/1/2030, exempt state and local sales tax for all installations under 10kw.

Change Is Coming Quickly

The next few years are going to be exciting as our projects align with the new energy code and our state moves to electrification of heating and domestic hot water. The grid needs new capacity. Renewable solar energy is currently our best option to move the needle toward becoming a carbon-free state.

If you have questions, drop me a line at erik.bedell@gly.com.