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The Duck Curve: A Review of California's Daily Load Predictions

Posted by Andrew Gong on Apr 10, 2020 8:19:27 AM

What Is the Duck Curve?

California’s electricity is supplied from a variety of energy sources, including natural gas, solar, hydro, geothermal, wind, and nuclear. The California Independent System Operator (CAISO) manages the operation of the state’s electricity grid, making sure that the total energy demand on any given day matches the total energy supply from the various sources. In order to continuously balance the grid, CAISO needs to be able to track and predict the volume of energy coming from all the state’s sources.In response to an ever-increasing volume of intermittent renewable energy—predominantly solar—being installed and added onto the grid, CAISO began preparing for the impacts it will have on net load (or the forecasted electric load minus the expected solar and wind supply). In a 2013 report, CAISO shared a chart that predicted these impacts from 2012 through 2020 that quickly became known as the “Duck Curve” because of its vague resemblance to a duck. The duck curve (shown below) is a snapshot of a 24-hour period in California on March 31st.

The graph starts with the actual net load profile from March 31, 2012 and March 31, 2013, followed by predictions through 2020 as the amount of renewable energy on the grid increases. The most notable features of the chart is the mid-day drop in net load, then the increase between 3 and 7 pm. There’s a dip mid-day because that’s when the sun is strongest and we get a high volume of energy from solar, and there’s a peak into the evening because solar is no longer a source of energy and there’s an increase in energy demand.

The original Duck Curve chart. Source: CAISO

CAISO noted that with the anticipated large scale deployment of solar, the net load’s mid-day dip and evening peak will become sharper and pose challenges to grid management. To reduce the increasing evening peak when energy demand is high, the solution will require adding other sources of energy to the grid to replace solar, but only during the peak hours.

Since the duck curve’s introduction in 2013, it has been used to influence decisions, such as the shift of peak time-of-use pricing in the evening to provide a pricing signal for customers to reduce their electricity consumption during those hours. There have also been additional investments in grid-connected storage, allowing some of the mid-day solar energy to be stored and used later in the day.

How Accurate Is the Duck Curve?

CAISO’s 2013 duck curve chart used data from March 31st and predicted the net load through 2020. Now that March 2020 is in the books, we can figure out how accurate CAISO’s predictions were. We pulled the hourly load data from CAISO’s website from late March and early April of each year, and compared it against CAISO’s predictions.

Note: CAISO did not provide the original methodology to create the duck curve, but we know March 31st fell on a weekend in 2012 and 2013, and it was clear skies for solar and fairly average temperatures across the state. Our comparison will look at days with the same clear-sky characteristics, but not necessarily the 31st of March for each year.

Predictions in the Duck Curve Predictions Are Really Close

When we compare actual net load (color) against the original duck curve (black), we can see that CAISO’s 2013 predictions were very close to actual net load profiles all the way through 2020. The mid-day minimum of net load has fallen lower and lower as California installed solar on over a million rooftops and added over 27 GW of solar energy to the grid. There is a notable morning mini-peak that appears around 7 am starting in 2016, but this is a result of using weekday instead of weekend dates to match the same clear-sky characteristics from 2013 and 2014.

But If You Dig in Deeper...

Expanding the data and taking a closer look, we do see some changing patterns in the net load profiles. When we plot the actual net load (color) for each day between March 15 and April 15 and compare it against CAISO’s predictions (black), the actual load starts to dip lower than CAISO’s predictions starting in 2017. Meaning, CAISO’s analysis in 2013 underpredicted the magnitude of the mid-day dip that we are seeing on the grid. Additionally, the duck curve has morphed to include a morning tail bump as well, further complicating CAISO’s grid operations strategy.

CAISO’s duck curve proved to be fairly accurate, and although the rate of solar installations slightly outpaced the predictions, the operator has been able to keep California’s grid stable even through challenging times like COVID-19. As California continues to lead the country in installing renewables, we will keep a careful eye on how the duck curve continues to evolve.

The original graph was traced to extract the data, so small errors may be present.

Data source:

Topics: electric grid, California

California’s Solar Mandate for New Homes: What You Need to Know

Posted by Gwen Brown on Aug 29, 2018 10:09:35 AM

[Editor's note: This article was updated on December 6, 2018 to reflect formal approval of the policy by the California Building Standards Commission.]

As you may have heard, California recently became the first state to mandate solar PV systems on all new homes. This is a momentous decision for the industry; it brings the benefits of solar, a historically niche product, directly to a significant portion of homeowners. The policy will dramatically expand the size of California’s solar market–already the most mature in the nation–and perhaps it will eventually inspire similar action in other states.

For California solar companies that position themselves effectively, this could open up some great opportunities to serve a vast new sector. In today’s article, we detail what’s required under the new policy so you can make sense of what’s changing and assess the market opportunities.

Interested in learning more about the resulting market changes, business opportunities, and how your company can get involved?Check out our recent webinar with Solar Power World!

What policy establishes California’s new home solar mandate?  

On May 9, 2018, the California Energy Commission (CEC) approved the 2019 Building Energy Efficiency Standards. What’s significant in this update to the Building Code is that, starting in 2020, every new home built in California will be required to have a PV system installed. (That is unless the building qualifies for an exception, of which there are a few). The policy got official approval from the California Building Standards Commission in December 2018. 

What types of buildings are covered under California’s solar mandate for new homes?

The code states that the solar requirement applies to “all low-rise residential occupancies including single-family homes, duplexes, garden apartments, and other housing types with three or fewer habitable stories.” This includes multi-family housing like apartment buildings as long as they are under three stories. And for single-family homes, it doesn’t matter how tall the building is–all homes of that type must comply.

California’s mandate of solar on new home requires solar PV systems be installed on all new homes, including both single-family and low-rise multi-family homes.California’s mandate of solar on new home requires solar PV systems be installed on all new homes, including both single-family and low-rise multi-family homes.

There are a few exceptions under which a home would not be required to have a PV system (such as including when there is limited unshaded roof space) or would be allowed to install a smaller system. Multistory buildings with limited roof space and homes that incorporate energy storage can qualify for a smaller PV system. Additionally, buildings that are permitted prior to January 1, 2020 will be exempted from the requirement.

What is required to comply?

One of the most important things to understand is the required size of the PV system under California’s solar mandate for new homes. The policy establishes a minimum PV system size for a home based on the building’s projected annual electrical usage. 

Minimum PV system size is calculated based on the conditioned floor space (square feet) and the climate zone where the building is located. (To determine what zone your building is located in, you can use the EZ Building Climate Zone Search App developed by the CEC.) In order for a home to receive a building permit, the builder will need to demonstrate that it will have a solar system of at least that size.

A map of California’s Building Climate Zones, relevant to PV system size under the state's solar mandate for new homesA map of California’s Building Climate Zones; the zone a new home will be built in will influence the size of solar PV system that must be installed under the state’s new mandate of solar on all new homes. To determine what zone your building is located in, the EZ Building Climate Zone Search App is a handy tool. (Image credit: CEC)

Aside from requiring compliance with the minimum system size, the policy allows some freedom for solar contractors and builders to meet the requirements in different ways. For one, developers could choose to install a community solar installation for a group of homes instead of putting rooftop solar on each building. However, they would need to be able to demonstrate that it would offer equivalent benefit to residents as if they had solar on their own home. 

Additionally, a variety of solar financing options are allowed. Systems could be owned by the homeowner (added into the cost of the home) or third-party owned. This means depending on what kinds of solar financing your solar company offers customers, you’ll have flexibility.

How do you determine the required PV system size?

The code includes two different paths for compliance, prescriptive and performance; either can be used to meet California’s solar mandate for new homes. The prescriptive approach utilizes a formula to specify the minimum PV system size (see the appendix at the end of this article for the formula and an explanation). This method is simpler but less flexible.

The performance method (aka “computer compliance method”) is a little more complex but allows for greater flexibility. The CEC has created a free software program (“CBEC-Res”) to allow contractors to model alternative PV sizes, based on different building characteristics like battery storage or demand response. 

Next Steps

Some details of the policy, including more specific guidance for compliance, are still being developed by the CEC. We’ll continue to share relevant updates as they are available. In the meantime, you can check out the resources below to learn more.

Finally, if you want to prepare your company to take advantage of the resulting business opportunities, check out Aurora’s recent webinar hosted by Solar Power World.

Watch the Webinar

Aurora Solar design and sales software enables solar design for homes not yet built because you can design based on roof plansAn example of a solar project site model created from building roof plans in Aurora–one of the ways Aurora makes it easy to adapt your solar design processes for this new solar market. Our webinar (linked above) demonstrates this process.

Additional Resources:

Appendix–Prescriptive Compliance Formula

The following formula establishes the minimum PV system size for a new building under the prescriptive approach in the 2019 Building Energy Efficiency Standards. For a full explanation, see section 7.2 of the 2019 (Draft) Residential Compliance Manual (a final version is still under development at the time of writing so this draft version is the latest guidance).

kW PV required = (CFA x A)/1000 +(NDwell x B)

Here’s what those variables mean:

  • kWPV = kWdc size of the PV system
  • CFA = Conditioned floor area
  • NDwell= Number of dwelling units
  • A = Adjustment factor from Table 7-1 (see below, center column)
  • B = Dwelling adjustment factor from Table 7-1 (see below, right column)

2019 Building Code Table 7-1 for Prescriptive Formula 

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Topics: solar policy, California

California’s New Smart Inverter Requirements: What “Rule 21” Means for Solar Design

Posted by Gwen Brown on Nov 8, 2017 9:30:00 AM

In the fall of 2017, California became the first U.S. state to require the use of advanced, or “smart,” inverters in solar projects (and other forms of distributed electricity generation). These changes, implemented through updates to “Rule 21,” require that inverters have certain capabilities to help ensure proper operation of the electric grid as more and more renewables are connected.

While these requirements are specific to California for now, the changes are representative of approaches other states are likely to consider in the future. So, if you’re a solar professional, it's a good idea to get familiar with these changes no matter where you’re based. In today’s post, we explain the new inverter requirements under Rule 21 and what they mean.

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Why Are These Changes Being Implemented?

The significant expansion of solar and other renewable energy sources is a huge opportunity—for tackling climate change, improving public health, delivering cost savings to consumers, and much more. However, it also presents new challenges for the management of the electric grid, which was originally built for one-way flows of power from power plants to the grid and then to consumers.

Customer-sited “distributed energy resources” (DERs)—like solar—introduce two-way power flow, as systems feed excess energy back to the grid. The variable nature of energy sources like wind and solar, which fluctuate depending on weather conditions, adds additional complications for grid managers.

California has led the nation in the deployment of solar and is likely to continue as the state works toward achieving its target of sourcing 100% of its electricity from renewable sources by 2045. As the proportion of renewables reaches unprecedented levels, there is a need for grid operators to have additional tools at their disposal to manage these resources and keep the grid running smoothly.

As the “brains” of solar projects, inverters can support grid management, but to date regulations have prevented the use of the full range of inverter capabilities.

Picture of the inside of an inverterSmart inverters, now mandated under California’s Rule 21, can help support management of the electric grid.

Beginning a few years ago, California utilities warned that advanced inverter capabilities would be needed to avoid potential grid disruptions. With more nuanced capabilities for determining when and how solar systems disconnect from and reconnect to the grid in the case of a power outage or other disturbance, smart inverters can help ensure that solar and other DER systems don’t make grid disturbances worse.

For instance, during and after a disruption on the grid, variations in voltage and frequency may occur. Historically, PV systems have been required to immediately disconnect when these conditions are detected; however, if a large amount of DER capacity disconnects at once this could further destabilize the grid. Similarly, the grid could be stressed if many solar installations reconnect to the grid at once after an outage, or increase their power output at too steep a rate. Smart inverter functions allow systems to remain connected to the grid under a wider range of voltage and frequency levels.

Requiring these changes now also has cost-saving benefits, because they may prevent the need for costly retrofits to the inverter fleet. These issues—both grid instability and the need for expensive inverter retrofits—occurred in Germany, where solar capacity expanded very rapidly over the span of ten years.

Beyond preventing grid disruptions, the use of advanced inverter functions has the potential to improve the stability of the grid. For example, dynamic volt/var operations (also called dynamic reactive power compensation) of smart inverters allow systems to help counteract voltage deviations on the grid. Furthermore, eventually, remote communication capabilities will be rolled out that allow grid operators to remotely adjust the operation of inverters to support the grid.

The Smart Electric Power Association and the Electric Power Research Institute note   that smart inverters may be one of the most cost-effective mechanisms for addressing many grid management challenges, and in some cases, “could help defer or avoid certain distribution, transmission, and electric supply upgrades.”

Craig Lewis, Executive Director of the Clean Coalition , a nonprofit that works to accelerate the transition to renewable energy and a modern grid, notes that “enabling the full suite of advanced inverter functionality is essential to bring high-levels of distributed generation online quickly and cost-effectively – in California and every other leading market around the world.”

On September 9, 2017, new requirements for inverters used in solar projects came into effect in California. These changes were implemented by the California Public Utilities Commission through significant updates to its Electric Tariff Rule 21 (or “Rule 21”), a set of existing interconnection requirements.

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What’s Changing Under Rule 21?

The revisions to Rule 21 are being implemented in three phases.

Phase One, which went into effect on September 9, 2017, requires that any solar project which applies for interconnection to the grid must use an advanced inverter capable of performing seven autonomous grid support functions. Inverters that are eligible for use under Rule 21 are those that have been tested and certified under the new UL testing protocol known as UL 1741 Supplement A (SA).

A complete list of eligible inverters can be found on the California Energy Commission (CEC) website . The list—which is updated monthly—contains over 3,200 eligible inverters.

One of the main changes under UL 1741-SA is that inverters are now allowed to operate under a wider range of voltage and frequency levels. As  Solar Power World explains , under the previous testing protocol, UL 1741, “the old interconnection requirements only allowed inverters to operate within a narrow range of... frequency and voltage requirements.” This meant that the use of many commercially available inverter functions, including those that offer grid support benefits, was prevented.

Graphic explaining Rule 21 Smart Inverter Requirements- Phase 1

Phase Two will establish communication requirements for inverters , setting standards for how inverters communicate with each other and utility systems. This will be important for enabling grid managers to eventually make remote adjustments to inverter operations to keep the grid running smoothly. Phase Two will also require that inverters have the capability to communicate over the internet. (However, internet connections for solar systems will not be required at this stage, because it has not yet been determined whether utilities or solar customers will be responsible for paying for internet connections.)

The exact date that Phase Two will go into effect is not yet determined, but it will be either March 1, 2018, or nine months after the release of an industry-recognized certification test standard for inverter communication protocols, whichever is later.

Graphic explaining Rule 21 Smart Inverter Requirements- Phase 2

Finally, Phase Three will require additional advanced inverter functions , “like data monitoring, remote connection and disconnection, and maximum power controls.” The specific requirements and timing of this phase have not yet been determined, although the Smart Inverter Working Group , which has been instrumental in establishing the details of Rule 21 revisions, has released recommendations (available here ).


How to Comply with Rule 21

To comply with the current phase of Rule 21, the main thing you need to know is that the inverter you select for your solar design must be one that has been certified under UL 1741-SA ; consult the CEC database  to be sure.

After choosing a certified inverter, some setup may be required to ensure that the inverter operates under the default parameters of Rule 21. As Solar Power World explains, the necessary settings can be determined during the interconnection process with the local utility and set up either remotely or through the inverter interface.

Coming Soon to a State Near You?

While California is the first state to take these steps, as a solar contractor it’s a good idea to be aware of these changes wherever you work, because other states are likely to be considering similar moves in the future.

Hawaii, Nevada, Arizona, Vermont, and Massachusetts are among states that may soon follow California’s lead. Quoted in Solar Power World, John Drummond, applications engineer at inverter company Chint Power Systems, says his company “expect[s] these kinds of advanced inverter functions to be required in the entire country in the next few years.”

As we work towards a future where clean, renewable energy is the norm, smart inverters will play an important role in managing the modern grid. We hope this article has given you a better understanding of how regulations are changing to manage rising levels of renewable energy and the details of Rule 21’s new inverter requirements for solar systems in California.

Editor's note: This article was updated in September 2019 to reflect California's passage of SB100 which sets a target of sourcing 100% of the state's electricity from clean energy by 2045.

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Topics: solar design, solar policy, inverter, smart inverter, California

Getting to 100% Renewable Energy: An Interview with David Hochschild of the California Energy Commission

Posted by Gwen Brown on May 18, 2017 12:00:00 AM

Commissioner David Hochschild serves on the California Energy Commission (CEC) , the state’s primary energy policy and planning agency. The CEC’s responsibilities include promoting renewable energy development; advancing energy innovation through investments in energy research, development, and demonstration programs; advancing energy efficiency; and promoting affordable, reliable, and environmentally sound transportation energy infrastructure. The California Energy Commission is one of California’s three governing institutions for energy, along with the California Public Utilities Commission and the California Independent System Operator.

CEC Commissioner David HochschildAppointed by Governor Jerry Brown in February 2013, Commissioner Hochschild fills the environmental position on the five-member Commission, where four of the five members by law are required to have professional training in specific areas. Hochschild’s career has spanned public service, environmental advocacy, and the private sector.

Prior to being appointed to the Commission, Hochschild served as a Special Assistant to San Francisco Mayor Willie Brown in 2001, where he launched a citywide $100 million initiative to put solar panels on public buildings. He went on to co-found Vote Solar, an advocacy organization working at the state level across the country to make solar affordable and accessible to more Americans. He served as executive director of a national consortium of leading solar manufacturers and worked for five years at Solaria, a solar company in Silicon Valley. From 2007-2008, he served as a commissioner at the San Francisco Public Utilities Commission. For his work to advance clean energy, Commissioner Hochschild was awarded the Sierra Club’s Trailblazer Award and the Department of Energy’s Million Solar Roof True Champion Award.

Recently, Aurora Solar’s Chief of Staff, Sunny Wang, and Content Marketing Analyst, Gwen Brown, had the privilege of speaking with Commissioner Hochschild—fresh off his recent TEDx talk —to get his take on the current state of solar and clean energy policy, here in California and beyond, and on trends and future developments in the industry.

Do you think that California is feeling an added pressure to double-down on its climate and clean energy efforts?

Oh, absolutely. I think the will has never been stronger than it is right now. California has the sixth largest economy in the world and is home to 40 million people—we're larger in many metrics than most countries in the world. I think particularly given recent events, leadership on renewables has shifted to the states.

Fortunately, most of the policies that really matter—in terms of accelerating renewable energy—are actually still made at the state level.

By that I'm referring to renewable portfolio standards, net metering, interconnection standards, rate design, state tax credits, etc. that really dictate the markets for clean energy around the country. I think the will is very strong to continue what we've started, and I have actually seen an increase in activity and interest here in California.

Speaking of renewable portfolio standards (RPS), California’s RPS sets the ambitious goal of obtaining 50% of the state’s electricity from renewable sources by 2030. For those who haven't been closely following California's progress, can you provide a quick update on where we are? Are there major hurdles for California to overcome in order to achieve this target sustainably?

Today, 27% of the state’s electricity is from renewable sources; that's up from 12% renewables in 2008. And, we're on a path not just to hit 50%, but to exceed it.

There are hurdles to overcome, however. One of these issues is renewable energy integration. That involves a number of different levers, including energy storage, regionalization, and load control options. Regionalization—having a broader balancing area to be able to draw on and send renewable energy to—gives you more flexibility. Load control enables us to better align electricity demand with times of high renewable energy production. This includes demand response measures, as well as electric vehicles that are designed to charge intelligently and at times of the day that support the needs of the grid.

You could think of the process of achieving high levels of renewables as having two phases. The first chapter of this work was really bringing down the cost of renewable technologies. That work has largely been successful, particularly with solar and wind. The prices of solar and wind have both fallen about 80% in the last decade, so we’ve seen really substantial cost reductions which are very good for the future of the market. The second chapter is integrating renewables successfully onto the grid.

Another related challenge that goes hand-in-hand with renewable integration is electrification. We want to see a migration of services that are now fueled by natural gas, diesel, and gasoline to being powered by this new, clean electric grid. That's everything from vehicles—we have 275,000 electric vehicles on the road today (a trend I am happily now participating in as of about a month ago)—to all-electric homes, electrified rail, etc.

Continuing on the topic of California renewable energy policy, part of the California Solar Initiative that the Energy Commission is advancing is the New Solar Homes Partnership program . Can you share some updates on the program and its successes?

The way to understand this program is that it’s really the glidepath for California to reach zero net energy in [building] code. The goal originally was 2020 as our date to mandate zero net energy in code and you don't want that to be an abrupt change. You want homebuilders already building a significant number of homes with solar before that becomes a mandate. This incentive program was created to help get that going.

One of the main challenges with new construction is that the homebuilder is not the occupant of the home. The builders’ main goal is typically to contain costs so adding extra features is often not what they are seeking to do.

This program helped kickstart that market, and in Southern California about a quarter of the new homes being built today are being built with solar.

Our energy markets to date have been built around fossil fuels–which differ significantly from renewables. From a market perspective, what will need to change about how we buy and sell electricity in order for our energy markets to function with higher levels of renewables on the grid?

Well, I think the first realization is that along with renewables comes distributed generation and a distributed model. Where California used to have just a couple hundred power plants providing all the electricity, today we have roughly 600,000 when you count all the rooftop solar.

As a result, intelligent infrastructure that's designed to allow for a friction-free market for distributed generation is essential.

That includes having the ability to meter distributed generation. It also includes having smart inverters that have telemetry and voltage regulation capabilities. So, for example, we can send signals to rooftop solar systems to tell them to adjust voltage to help support the grid. I think that's one of the main changes that is needed.

I also think you're going to increasingly see a movement among utilities towards more of a "pipes-and-wires" model, where their focus shifts from generation to managing the interactivity of all these other generators and consumers.

We need the utilities to succeed—I want to be clear about that. I think it's really in everybody's interest to have the utilities succeed, but what they are doing is going to change.

I also think that, increasingly, the role of utilities is going to shift towards transportation. I believe the electrification of the vehicle fleet is one of the single most exciting potential developments in the next few years. It offers great promise—not just to reduce greenhouse gas emissions from our transportation sector, which is California’s greatest source of emissions right now—but also to help facilitate higher penetration of renewables.

Do you believe it’s possible to supply 100% of our electricity from renewable sources?

I absolutely believe it is possible. I think it's actually inevitable. The real question is whether we get there fast enough to make a meaningful difference on climate change.

Here's the big picture. Over the long haul, basic laws of economics hold that as reserves of finite resources like fossil fuels—whether they are reserves of coal, or petroleum, or natural gas—become constrained, the prices go up.

Technology, on the other hand, as it scales, prices go down—whether we're talking about cell phones, flat screen TVs, electric vehicles, or solar panels.

The foundational technologies of the clean energy future are all going down very steeply in price: solar PV, wind, energy storage, LED lights... that is reason for great optimism about our ability to achieve this future.

There will be a lot of adjustments to be made. We're going to have to be much more nimble about things like load control, for instance. The traditional model has been that electric load (electric demand) drives electric generation... your factory turns on, and you have to turn on a fossil-fuel burning power plant.

Now, for some subset of that load, it's actually going to switch; renewable generation is going to drive electric demand. For instance, if you have a fleet of electric vehicles and you have some flexibility in the time of the day you charge them, or you have a building that needs to be cooled but you can do some pre-cooling, you have windows of time for electric demand that can be aligned with renewable generation. That will become a much more refined science.

There are plenty of other technology hurdles to cross as well—but there is nothing about the transition to 100% renewable energy itself that is outside the realm of a solvable problem.

It's all solvable; it's just new types of problems, and our ability to solve these problems has gotten infinitely better.

I look at our capabilities and where we are in our technology development at the moment, and even if innovation were to basically halt and we were just working with current pricing and current technology, we could get to 100%.

The good news is it's actually getting better. Every year, we're getting larger and more efficient wind turbines, more efficient solar panels, and cheaper batteries with longer duration. The technologies are all getting incrementally better every year so I have no doubt we will get there.

And, now there are cities, like San Diego, and whole states, like Hawaii, that have mandated 100% renewable energy. San Diego is the first major city in the United States to mandate 100% renewables by 2035, and Hawaii has mandated it by 2045. That's already underway.

The solar industry requires cooperation between different actors, such as businesses, utilities, and policymakers. In your career, you've worked in the solar energy space from many different perspectives—including public, private, and non-profit. What are your thoughts on the state of cooperation among key solar players?

Well, I think there is room for greater coordination in the industry. Early on, the solar industry was fractured in terms of industry associations; there were multiple overlapping associations. That has gotten somewhat better but it is not entirely resolved. The parallel is made, for example, to the NRA. There's not a National Pistol Association and a National Shotgun Association, right? And the NRA is pretty effective.

I think there is more maturing necessary, and I would like to see more "pan-renewables" advocacy and collaboration where everyone unifies around the vision of 100% renewable energy and the electrification of almost everything. I think there's a role for all technologies that serve that purpose, whether it be geothermal, solar, wind, or biomass energy, energy storage, or electric vehicles.

Where do you think we can expect to see new or significantly refined policies encouraging solar adoption in the next few years—either within or outside the United States?

One area is Mexico, which the California Energy Commission has been working with quite a bit on promoting clean energy policy and sharing best practices. The CEC has signed Memorandums of Understanding (MOUs) with the Mexican states of Aguascalientes and Jalisco to cooperate around clean energy, and collaborates with Mexico’s Ministry of Energy under a 2014 MOU signed by California Governor Brown and Mexican Secretary of Energy Pedro Jaoquín Coldwell. We've seen some very exciting developments in renewable energy pricing, and as a result, we're now seeing Mexico think seriously about renewables.

For example, they're now looking closely at energy storage—what its role should be in the future of Mexico and what policies they should adopt. These are things that weren’t under serious consideration about two or three years ago because renewables were seen as too expensive.

Commissioner Hochschild signs a Memorandum of Understanding with the state of Aguascalientes Mexico
Commissioner Hochschild signs a Memorandum of Understanding with the state of Aguascalientes Mexico on behalf of the California Energy Commission. Photo credit: California Energy Commission.

What developments under these MOUs are you particularly excited about?

One of the most exciting things is how greater participation in clean energy markets is leading to financial innovation. Banks and other financial institutions have to think about how to finance renewables and that has a cascading effect, even to educational institutions. Until recently in Mexico, you could not get a master’s degree in renewable energy, now a university in Guadalajara, Jalisco just launched the country’s first renewable energy master’s degree program.

All of these changes are happening right now before our eyes. It's changing so quickly it’s hard to track. For example, the states of Jalisco and Aguascalientes, which the California Energy Commission has signed MOUs with, have both recently adopted fleets of electric vehicles. Those are the some of the first states in Mexico, if not the first, to formally adopt fleets of electric vehicles and that is thanks to some of the collaborative efforts between the Commission and Mexico.

What is the most innovative solar design you have ever come across?

That’s a good question… there have been many of them. I've been involved in solar for my whole career, and some of the most innovative things I’ve seen were things that didn't ultimately work in the market.

But, the truth is, the things that I'm most excited about are not what I'd call revolutionary innovation, but rather what I'd call evolutionary innovation.

It's things that are not particularly sexy or noteworthy, but which are the incremental improvements driving the whole market.

Every year the efficiency of solar panels and inverters has been going up. The early solar panels had 5% efficiency, right? Now they're roughly 20%. The early inverters had about 60% efficiency—so you would lose over a third of the power just converting it from DC to AC. Now, utility-scale inverters are at 99% efficiency. It wasn’t an overnight change; literally every year they became 1 or 2 % more efficient, with little tweaks and improvements.

That evolutionary progress is what I find most exciting. That’s what's been working and I'm optimistic that will continue.

Topics: Solar Spotlight, California

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