Microgrids 1.1: The Basics

There are a number of key and catchy words in the energy and environmental world in which I live…algorithms, net zero, parity, equity, resilience…microgrids. I love them all, especially the latter as a consultant in that new and daring space. We’re spearheading a project to develop 32 energy-resilient, solar + storage systems now for Southern California cities. If the grid goes down, a facility can still function.

Microgrids are a hot topic because they provide energy resilience. In Monterey County, EcoMotion worked for a school district that sought resilience to keep its students from wasting an educational minute. We found a cost-effective means to finance solar coverage for every campus, battery energy storage, and microgrid controls. Supported by wireless energy management capabilities, the microgrids are designed to operate indefinitely in a carbon-free mode during a prolonged outage. This case study will be presented later in this series.

But let’s get back to basics: What are microgrids? Literally…they are really small grids. Some of them serve islands or ships and are autonomous, while others are tied to the grid and spring into action when the grid goes down. We’re going to focus on the latter:

For the purposes of this discussion and series, microgrids are facilities or geographic areas that can “island” from the power system and operate in parallel with and independently of the power system. We’ve developed solar + storage microgrids. Between the two, and tight controls, the microgrids can be operational and autonomous. They can be carbon-free. And they can be financed.

Thomas Edison started pretty small at the Pearl Street Generating Station in the financial district of Manhattan in New York City in 1882. Edison Illuminating Company’s coal-fired power plant originally served 400 streetlights and 82 customers. It was actually a cogeneration plant as steam heating was providing to adjacent manufacturers and buildings. It was a small grid…a microgrid…served by a single power source.

Later the Edison companies got bigger and bigger, with not only local distribution but also long-distance transmission tying in generators far away. As centralization of power generation occurred, gone was its cogeneration, and gone was resiliency. Unplanned outages cause widespread disruption. While tapping the economies of scale for power generation, the central systems that we largely rely on today in America fundamentally lack the resilience that lots of small systems create.

So back to microgrids and addressing today’s realities. Microgrids can augment and shore up the power system by being able to operate and provide power to critical loads. In the event of an emergency, they can provide for refrigeration, medical equipment, or IT systems and communication.

Many hospitals, police and fire stations are already energy resilient. They have generators – typically gas-fired or diesel – that operate only when the grid goes down. New age microgrids have day jobs. They can generate savings during normal times and serve highly valued resiliency during outages.

During Superstorm Sandy, there were few pockets of light in and around New York City. One such pocket of light was Coop City, a housing development in the Bronx. Its power plant is configured to run in sync with the grid in normal times, and to be able to generate on its own during outages. Normally, ConEd buys excess power from Coop City, but during the superstorm, it was fully functional in islanded mode. This case study of a money-making, quite large-scale microgrid will be presented later too.

A colleague that I admire, Peter Asmus of Navigant Research, stated the other day to me that the current state of microgrids is pretty clear: Everyone wants one. This is especially so in California where PSPS (Public Safety Power Shut-offs) events are wreaking havoc on homes and businesses. Imagine your utility telling you that they are shutting down for the next several days due to extreme conditions…so sorry. Really, this is a sorry state of affairs. Can carbon-free microgrids be designed so that they pay for themselves, and cover you when the grid goes down, planned or unplanned?

Microgrids 1.2: Today’s Components

This second part of EcoMotion’s 10-part microgrid series digs into microgrid components: the hardware and the software that make up a new-age microgrid’s infrastructure.

There are three primary components to what I’ll call “green microgrids:” generation, storage, and controls. Smart providers – companies like Schneider and Scale – are working to provide these in pre-engineered packages. Let’s take them one by one.

The first component is generation. Microgrids can have a single source or multiple sources of generation. Early microgrids were generally powered with back-up generators. They were resilient for as long as their fuel supply lasted, be it a tank of diesel or natural gas. While the gas grid fails only about 1/20^th of the time that the electric grids fail, it does fail. As such, there are natural gas generators on the market backed up with propane tanks… back-up to the back-up!

EcoMotion’s green microgrids generate and then operate on solar power, a renewable resource that keeps on giving. Paired with storage to ride through the night, solar provides an ongoing source of energy. In the Santa Rita microgrid story that we’ll tell in a future edition, each campus microgrid has solar arrays sized to power annual energy use.

The second component is storage. It is costly but enables microgrids to be powered with intermittent renewable power. Microgrids can operate using real-time power generation during the day, and then rely on stored energy at night. To reduce the amount of costly storage required, it makes sense to identify critical loads. These can be wired into a critical load sub panel which is powered on during an outage.

To size the storage – be it Tesla, LG, Samsung, Invinity batteries – we focus on the daily power requirement of the facility in emergency mode, and its critical power requirements. How many kilowatt-hours are required each day? How does this compare with solar generation throughout the year? (Naturally, winter production is low.) Microgrid storage sizing is based on the critical load, the anticipated solar generation, and the net requirement. Days with little sun will require a further reduction in emergency loads.

The third major component is the controls. They sound like a big deal, and they are in terms of functionality. In terms of size, however, microgrid controls are really small. A notebook computer may constitute the controls, but software is the name of the game. Some companies in this space like Geli only do software. They have developed proprietary “algorithms” that drive the controls and optimize on generation and storage and the grid interface.

Proprietary systems are programmed to address different use scenarios and optimize battery use: First, when the grid is fully functional, the controls are optimizing solar and storage daily. The microgrid is in sync with the grid, operating in parallel. By loading up the batteries with solar and discharging at costly peak periods… the controls are enabling energy arbitrage. Excess solar goes into the grid to be net energy metered, earning credits to be redeemed on the bill.

Now the grid goes down. This is a new use case. No longer in sync and parallel with the utility grid, the microgrid now is “islanded.” A switch/breaker safely disconnects the microgrid from the grid. That’s called the Point of Common Coupling. Now the system is running independently… a mode in which recharging the batteries with solar is key, as is staying within an energy budget for long-term resilience.

A well-designed and controlled solar + storage microgrid can operate indefinitely. Furthermore, these green microgrids are carbon-free and silent. They have day jobs that provide ongoing savings. They also have the potential to sell grid services in the future.

You can see why it’s easy to advocate for fully integrated, solar + storage microgrids! In our next brief in this Microgrid series, 1.3, we’ll continue to bring the microgrid concept to light with two very different examples of microgrids: Stone Edge Farms in Sonoma and Coop City in the Bronx.

Microgrids 1.3: Two Case Studies

This third brief in the ten-part series on microgrids is intended to shed light on the concept we’ve been developing. In Microgrids 1.1 we talked about the genesis of microgrids, and what we call green microgrids. In Microgrids 1.2 we delved into the three major components. Here we present two wildly different microgrid case studies.

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Let’s begin in New York. Co-op City is one of America’s largest housing developments. It hosts one of the largest microgrids in the world. Co-op City was built in the late 1960s on 320 acres in the Baychester section of the Bronx, one of New York City’s five boroughs. I remember when it was built. It has 15,372 apartments in 35 towers serving a population of 60,000 residents. It also has seven clusters of townhouses, eight parking garages, three shopping centers, a high school, two middle schools, and three grade schools. If it were incorporated, it would be New York State’s tenth largest city.

By the early 2000s, its owner – the Riverbay Corporation – recognized that its dated central heating plant and 6 MW back-up generator needed replacing. Repowering the facility enabled far greater efficiency and reliable onsite power. The new 40 MW Siemens combined-cycle natural gas power plant was commissioned in 2011. With a 24 MW peak load, Co-Op City sells excess power when Consolidated Edison calls for it. The plant cut Co-op City’s energy bill by $15 million a year.

The community’s islanding feature – to become a microgrid – was an added benefit that has shined brightly and gained recognition due to Hurricane Sandy in October 2012. When nearly all of New York City was blacked-out, Co-op City was fully functional. It was powered and heated thanks to its power plant tri-generation facility that generates electricity, heat, and cooling. Its plant operator noted that “We weathered the storm well.” There was no flooding at the plant, and in addition to serving the residents with uninterrupted power and heat, Coop City’s plant operators were supporting Consolidated Edison with grid support, specifically VAR support (volt ampere reactive) for the surrounding neighborhoods.

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Stone Edge Farm and Winery is a 16-acre organic farm and vineyard located in Sonoma, California. The farm produces heirloom vegetables, fruits, olives, flowers, honey, eggs, wine grapes… and world class Cabernet. It’s owned by “Mac” and Leslie McQuown who are dedicated to addressing climate change. Now the farm is not only known for its organic Bordeaux-style varietals, but it has also become a showcase microgrid.

The rather complex project was built over a five-year period by project engineer and general contractor, Craig Wooster, now deceased. His legacy is the Stone Edge Farm Microgrid, a demonstration of taking a footprint “As low as you can go,” to what some call a “Sub-zero carbon footprint.” His vision and application also led to the project being called the Stone Edge Farms University, as many interns have flocked to the farm to learn about its innovative and integrated systems.

The project has 12 solar arrays on ten buildings, 553 photovoltaic panels constituting 160 kW. It features four types of batteries, including Aquion which use seawater chemistry, Tesla Power Packs, a 65 kW Capstone natural gas-fired microturbine, and a set of “hydrogen devices.” These include an electrolyzer to create hydrogen from water using surplus solar power. The hydrogen is stored to refuel the farm’s Toyota Mirai, and can be fed into the farm’s three fuel cell “hives” to return the hydrogen fuel into electricity.

We’ll discuss Stone Edge’s utility interconnection in a coming article in this series, but to whet your appetite… Stone Edge Farms has been completely islanded for the past nine months. Now “Mac” has his engineering team – led by Ryan Stoltenberg of Heila Controls –designing and building a microgrid at another winery… this time a DC microgrid.

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There is a growing list of notable microgrids ready for investigation and emulation. Other exemplary microgrids include the Kaiser Permanente hospital in Richmond, California, the University of California at San Diego, Borrego Springs, the Blue Lake Rancheria, and the Miramar Marine Corps Air Base. Microgrids come in many sizes and in many forms. The next article in this series discusses six microgrids developed by EcoMotion for a school district in Monterey County.

Microgrids 1.4: The Santa Rita Union School District Story

This story is about EcoMotion’s own first adventures with microgrids. We were hired by the Santa Rita Union School District in October 2015. It’s an elementary and middle school district in Monterey County, California… specifically in Salinas, the home of Steinbeck.

A District official there had heard about Tesla’s “Giga-factory” and wanted to bring batteries to her campuses to keep kids in school to learn despite power outages. Batteries, however, are expensive and the District wanted 7.5-hour duration… enough for campuses to ride through the entire school day. Three years later, I’m happy to report that all six campuses got the batteries, and as a bonus, the campuses are now also 100% solar-powered.

I credit my colleague Michael Ware. He recognized that if the campuses had solar, they would qualify for a Pacific Gas and Electric (PG&E) rate change. The solar would not only provide green kilowatt-hours at a discount, but the rate change would eliminate utility demand charges. In combination, the savings were significant and big enough to pay for the costly batteries.

At the end of the day, the microgrid systems – made up of solar arrays, batteries, and controls – were fully financed. The cost is virtually the same as the District used to pay to PG&E for grid power. That’s what we call parity… the same price. As PG&E rates escalate, the microgrids will be providing small savings to the District each year.

We began by analyzing the electric loads for each campus. Loads vary by season at schools. We determined an “average load,” and then with our colleagues at Avalon Batteries, we ran probabilities of the percentage of the time that the school would have ample power based on average conditions. If we could “hit” an 80% or 90% coverage in any given month… that was sufficient. Our job was to serve critical loads with costly batteries. Too many batteries would have meant higher costs, and thus a higher PPA rate, and we wouldn’t have achieved parity. To make the systems economic we had to thread the needle between resilience and cost-effectiveness.

Imagine this perfect storm scenario: It’s 8:15 and all teachers and students have arrived at school. It’s raining and dark, thus zero solar production. The batteries are full… but that’s it! Then a tree knocks out one of PG&E’s power lines and our microgrids must power the schools all on their own. The schools go into “battery mode.” Using the wireless control systems for all HVAC that we helped install, the District cuts the HVAC except minimal ventilation. Staff has been trained for battery mode, and all appliances are turned off. All critical systems – refrigerators, communications, lighting – remain running operable for the duration of the school day—7.5 hours! The students and teachers are safe and learning, all while the storm rages outside.

Points of interest along the way: SolEd Benefit Corporation is to be credited for developing the systems with us. SolEd shared our vision of using the solar in combination with batteries to provide daily resilience. Many financiers shied away from the project given the novel PPA proposed that mixed revenue generating (solar) and non-revenue generating assets (batteries). Finally, Generate Capital, led by Jigar Shah, got the vision and bought the systems.

Getting interconnected with PG&E was a long process. Even more trying were technical glitches between the inverters and the control systems that prevented the “battery mode” from working as planned. The solar is big and visible and has been providing savings as planned, but for two years the batteries have not been properly controlled. Fortunately, and just this month, new controls will be installed and the system should be fully operational this spring.

At the end of the day, the SRUSD story tells many lessons. Perhaps the biggest lesson is that you can pair solar and storage and controls, finance the package, and reap multiple economic, environmental, and societal benefits. At SRUSD, a model was crafted that provides carbon-free power each and every day. When SRUSD’s microgrids are fully tuned in, they’ll be able to operate indefinitely when islanded from the grid.

Microgrids 1.5: Critical Loads

In the last article in the 10-part series, we focused on the Santa Rita Union School District and how microgrids there were designed to cover average loads. As part of that project, we installed wireless thermostats to control HVAC. These loads would be cut in the event of a power outage, when each campus goes into “battery mode.” These are the times to cut loads.

Energy resilience is expensive stuff. The more resilience you want, the more it costs. Thus, it makes sense to identify what’s critical. What’s essential in a power outage? A computer system? A medical device? Don’t forget the coffee maker! EcoMotion is working with a number of sites now, slimming down the critical loads to about ~20% of the facility’s full load. Why so small? Again, to make resilience affordable. If you want 100%, you will pay dearly. At 20%, systems can often be financed at parity.

When developing microgrids, try to avoid this question: What do you want to back up? Why? Because it seems that everyone wants to back up everything. That’s expensive. Instead, we ask a fundamental question: What’s the purpose? What is this resiliency for? Is it to maintain refrigeration, or communications, or to provide for cell phone charging? Is it to power medical equipment or to maintain delicate scientific experiments? Is it to keep kids in school, data centers operational? This clarity defines our target.

So now with our resilience target in place, we dig in. We now know how much energy we need to store. Let’s say the purpose is to maintain the IT functions at a company; or to maintain refrigeration at a food-service facility. Those are the functions that are critical; those are the loads that constitute our design. We size the storage to cover these loads for the duration selected. Loads that are not critical are not backed. They might include air conditioning, resistance heating, architectural lighting, elevators, EV charging, and waterfalls.

So how to do it, how to limit the microgrid’s functioning in battery mode? If a facility has a sophisticated energy management system, it can be programmed to toggle back loads to critical only in “battery mode.” Many large buildings have custodial lighting and ventilation pre-programmed. They can be programmed for “battery mode.” Less sophisticated facilities do it the good, old-fashioned way…. humans taking actions such as turning off escalators, elevator banks, fountains… and even non-essential lighting. In schools, staff is instructed to steer clear of photocopiers during these periods.

Another strategy is to wire critical circuits into a subpanel. Only these circuits will be backed up when the grid goes down. In some instances, wiring a subpanel can be easy… mounting it right next to the main panel and rerouting select circuits. This is how PowerWalls are installed for household installations. In other cases, trying to wire critical loads into subpanels can be extremely challenging and just not worth it. Imagine a school campus with multiple buildings far afield. Controlling specific loads at the building level in this instance is near impossible. Another complicating factor for subpanels is trying to meld together loads operating on different phases in a three-phase system.

In some cases, wiring subpanels can be more expensive than adding more battery capacity to cover the entire load. Then you can forget about rewiring for critical loads altogether. That is what we did in Santa Rita Union Elementary School District. But remember that critical loads there are still in focus, relying on the energy management system to cut HVAC loads and trained administrators, teachers, and staff to cut off all other unnecessary loads.

The goal for sizing resilience is to enable a facility to get through night one. Then the sun comes up and solar recharges our microgrid… enough to operate that day in battery mode and get through night two. By carefully managing daily energy use, and only powering critical loads one way or another, solar + storage microgrids can operate indefinitely in a carbon-free mode.

Our colleague, Kirk Stokes, at MBL Energy stressed the importance of client expectations regarding microgrids given the high cost of batteries and resilience. “They have to understand that battery-mode operations are different than grid-connected times. You’ve got to set expectations: No HVAC. No electric appliances. That’s it. That’s how you create resilience at a reasonable cost.”

Microgrids 1.6: Giving Batteries a Day Job!

This sixth article on microgrids works an angle: The idea is to give expensive batteries a day job so that they earn their keep, so that they earn revenues. Solar earns money… so should batteries. Right?

EcoMotion is currently working for Clean Power Alliance and its member agencies to identify facilities for energy resilience. Each member agency was able to nominate up to five sites for our analysis. Further, our charge is to model solar + storage + energy resilience such that the facilities are operable during short-term and prolonged outages. These are carbon-free microgrids and our goal and challenge is to finance the diverse portfolio of projects at parity.

Let’s unpack that, starting with a single site. We determine its total load during normal use, and then its critical loads—the smaller portion that is essential to operate during an emergency. We then size solar to cover the annual load, and storage to provide power for critical loads. We want enough storage to ride through the night in “Battery mode.” Maximum conservation. Then solar will recharge the batteries the next day.

The obstacle is that batteries are expensive; they tax the balance sheet. Thus we want the batteries to help pay for themselves. That’s why we say, “Give the batteries a day job.”

So what does this “Day job” look like? Imagine this… we are going to take the majority of the battery’s energy storage – say 75% of it— and put that to work. We are going to a) do energy arbitrage, and b) cut peak demand. In the future, we may be able to sell “ancillary services” to utilities… things like resource adequacy, frequency control (up and down), and power factor control.

Energy arbitrage sounds like a troubling financing scheme. In this instance, it is simple: buy and/or generate inexpensive energy, store it, and then discharge it during peak periods when energy is expensive, offsetting peak rates. It’s a basic financial play… enabled by having storage. Let’s consider an example. Let’s say that I have a building served by Southern California Edison’s TOU-GS-2-E rate. That costs a whopping 62.5 cents per kWh for summer on peak power, versus 16 cents off peak. If I store the solar electricity I generate during the day when energy is cheap, and then I use it in the evening when it costs 62.5 cents (and my solar panels are no longer generating energy because it’s dark), you can see dramatic savings.

One of the most attractive policies to incentivize solar power has been a series of rates offered by California’s investor-owned utilities that raise energy charges and lower demand charges. PG&E’s A6 rate, SCE’s Option R, now E, and SDG&E’s DR rate grant customers reduced demand charges as long as their solar provides at least 15% of peak demand. After the rate switch, the demand charges plummet, providing solar economics with a nice boost.

The flip side of this benefit is that when batteries are installed with solar… batteries that are expert at picking off spikes in the load profile… the high cost of load spikes is much less dramatic. There is less “Profit” to harvest from demand-limiting activities. Perhaps this conflict in rate structures and incentives will be addressed by the CPUC’s microgrid rate design. All that said, there are still some savings to be realized by cutting peak demand.

Let’s throw out some numbers: A city hall in LA County had baseline usage of 418,803 kWh a year at a cost of $76,987. After ~210 kW of solar, the cost falls to $31,429. (Solar cut $45,558 from the power bill). We model 300 kWh of storage. Its “Day job” will earn $12,606, resulting in a net “Utility bill” of only $18,823. In this instance, solar savings are 4x storage savings… but important to project economics. Another coastal city hall uses $88,000 of power, solar saves $67,000, while storage savings are $9,000. In that instance, solar savings are 7x storage savings.

One more wrinkle: Let’s imagine that your battery, in the course of doing its day job, discharges all the energy it has stored in pursuit of maximum savings at the exact moment an unexpected outage occurs. There’s nothing in the tank, and the resiliency benefit is zero! That’s why we don’t give the entire battery a day job. We put 75% to work maximizing savings, and leave 25% untouched, always ready to power the facility during an outage. That’s our “Resiliency carve out.” If the outage is announced in advance (like a PSPS event), then the entire battery can charge up and be ready to provide resilience.

Developing cost-effective systems—systems that we aggregate and then take to market for financing—is challenging. We want a PPA rate that costs no more than these facilities paid without solar, storage, and resilience. I call it threading the needle. You need enough expensive storage assets to use and generate revenues, while leaving a carve-out for resilience. The storage savings, while a fraction of the solar savings, are important. Make sure to give your batteries a day job!

Microgrids 1.7: Interconnection

This chapter in the 10-part series on microgrids focuses on interconnecting microgrids with electric utilities. Microgrids have many virtues for their users and their host utilities, but in California, it’s been challenging getting them interconnected to the utility grid. It’s complex and technical stuff, so we’ll work to keep it simple. EcoMotion was in touch with three leading microgrid developers — MBL Energy, Engie, and Schneider Electric — and met with their super-knowledgeable engineers to discuss their interconnection experiences in California.

Kirk Stokes is the head of energy storage solutions for MBL Energy. He put microgrid interconnection in a seasoned and useful perspective in our conversation in the recent episode of The NetPositive Podcast. “Some context,” advises Kirk. He explains that it’s taken a couple decades, but now utilities are comfortable hooking up net energy metered solar systems. Utilities wanted to make sure that systems automatically shut down during an outage so that linemen are not in danger of power back-feeding. Thanks to clear protocols, and years of familiarity, there are now expedited permitting processes for solar.

Unlike solar systems that operate daily and are then disconnected if the grid goes down, emergency generators sit idle and power up when the grid goes down. This might seem threatening for the same reason: back-feeding. But utilities have been comfortable with generators for years. Generators have been successfully operating for decades, controlled by Automatic Transfer Switches (ATS) that shut off utility service and replace it with generator service.

Now, says Kirk, we add a new wrinkle: Instead of solely operating during normal grid-tied operations as solar + storage do, or during outages as generators do, microgrids operate in both grid-tied and outage modes. To a utility planner, they look like small generating plants, and that raises concerns, largely the same concerns about back-feeding into the utility grid. So how can utility concerns be addressed and allayed?

For EcoMotion’s Santa Rita project, interconnection was delayed by engineering reviews, the requirement that a specific relay was installed for the six microgrids there, as well as third party engineering reviews. Relays are electrically operated switches that open and close circuits by receiving electrical signals from outside sources. Given the utility requirements, at a minimum, the process to gain permission to operate takes a year. That’s frustrating and costly. Instead of relays, Kirk recommends designing systems that employ Automatic Transfer Switches that are trusted by utilities, specifically UL-approved Automatic Transfer Switches to shorten the process while achieving the same safety result.

Our colleagues at Engie report on challenges with interconnection. Engie is developing microgrids throughout California. Our colleagues report that, yes, utilities are getting more familiar with these projects, but the approval process can be tough sledding. Engie often successfully uses a Schweitzer Engineering Laboratories SEL 700 G Relay to control the breaker that will island the microgrid. In the event of a grid outage, the relay senses the disruption and “throws” the breaker. When breakers are open, no power can pass through them in either direction.

Note that breakers in the old days were mechanical. If they were broken, someone would literally have to flip them back on. Now there are motor-operated breakers that operate with their own battery back-up power. (Both the relay and the breaker have to have this separate power supply). Utilities are understandably concerned about the relays and the breakers. Schneider’s experts note that utilities have come a long way in the past 3 – 4 years in the design approval process. Four years ago each microgrid project was new and unique. Now there are lots of projects and thus, “Generally, interconnection has gotten a little better.” The use of the SEL 700 G has proven to be a viable pathway for interconnection.

Colleagues at Schneider Electric agree that utility interconnection is still a challenge. In fact, “It’s the biggest unknown on any project,” noted a seasoned professional there. And there are different ways to get permission to operate a microgrid. One means is to promise to never export to the grid, but then you’re losing value. For a private school in Ojai, the utility required a downstream panel and utility control of a relay using a wireless system to take the microgrid offline. That was one of a kind.

Yes, there are inherent complexities that make interconnection a custom approval process. All microgrids are different. They have different use patterns, sizes for solar and storage, and different wiring, complex, and sometimes aging, switchgear. Hooking up a microgrid is a quantum leap in complexity compared to a solar system. They require lots of extra work, designing a system that can seamlessly transition from grid-connected, to grid-independent, and back. Then you throw in different utilities, inspectors. It’s often an “arm wrestle” to get a microgrid hooked up and interconnected.

To address the interconnection issue in a comprehensive way, Schneider is developing its Energy Control Center. It is a large, UL-listed electrical box that includes controls as well as relays. It is where solar lands and storage lands, generators too. It is the switchgear and has a smart, main electrical panel to control loads. Optimally the ECC is installed during new construction; they can also be wired in retrofit mode to control everything downstream.

One of the most attractive features of the ECC is that it eliminates the need for critical load subpanels. Instead, it prioritizes circuits based on the power that’s available from solar, batteries, and/or generators. As there is sufficient power, the ECC steps up its delivery of power from solely “critical loads,” to “essential loads,” and to all loads when there is ample power. So far, Schneider has developed two standard units, rated 800 and 1,200 amps. Other sizes are engineered to order. The ECC goal is “a comprehensive machine” with auto transfer switch, the ability to balance loads with available resources, and to island with utility confidence.

Practices for the interconnection of microgrids will evolve. Over time, there will no doubt be standardization that will streamline the permitting process and utility interconnection. Stay tuned. In the next chapter of this series, Microgrids 1.8, we explore the pros and cons of generators in augmenting microgrid operations.

Microgrids 1.8: Let’s Discuss Generators

This is the eighth article on microgrids… a technology so pertinent to the times. Much of the West is currently on fire, and as a result, energy resilience is top of mind and of paramount importance for many facilities and homes. EcoMotion specializes in solar + storage + microgrid control solutions… with resiliency works now involving key facilities in ~30 cities.

In many of the municipal facilities that our teams are evaluating for solar + storage, there are already generators. So, do these facilities fit into an energy resilience program? Are they covered already? Do generators complement solar + storage, or must these facilities forgo any opportunity for renewable, zero-carbon resilience?

Generators have been used for decades for critical facilities such as hospitals, police stations, pumping stations, fire stations, etc. They often run on diesel fuel, are closely regulated by local air quality control boards, and need to be routinely tested. For those that run on diesel, the generator provides resilience for as long as there is fuel in the tank. Other generators are hooked up to natural gas lines… which fail in emergencies only 5% of the time that electrical grids fail. Some natural gas generators are now backed up with propane tanks. Again, a finite amount of fuel.

Solar + storage microgrids are more costly, complex, and limited in some ways, but have a huge advantage in terms of fuel. Solar keeps on giving. So, as long as we can design microgrids that manage onsite energy use during emergencies to match the facility’s loads with the amount of incoming solar— buttressed with storage of course—the solar + storage microgrids can operate indefinitely and carbon-free.

EcoMotion is working with many Southern California cities now that have generators. Given their climate protection goals, they are keen to call on solar first and revert to “normal” generator back-up only as needed. This protocol can drastically cut the carbon footprint… alleviating greenhouse gas emissions that exacerbate the climate crisis. This is not only beneficial to the fight against climate change, but also to our air quality as diesel generators emit particulate matter that contains over 40 toxic air contaminants, in addition to greenhouse gases. If we can prove the carbon-free model, then the generators can ultimately be retired.

But wait! A hugely powerful case can be made to integrate existing generators into microgrids. As we all know, one of the drawbacks of variable solar energy is that we cannot always predict the extreme outlier cases when solar production is at its lowest. We begin sizing solar and battery systems by looking at averages, not extremes— average solar production in a given location and a facility’s average load. To size a system to cover those most unlikely cases—the toughest 2% of the time – requires investing huge amounts of money in equipment that is rarely needed. Generator capacity is a fraction of the cost of solar capacity.

Those times when solar + storage cannot provide enough capacity is when generators can be useful. By relegating the generator’s use to only those most critical periods, run times can be drastically diminished, and solar and storage system sizes can be reduced. For this reason, generators are currently being specified by some developers for new microgrids. They can be remarkably well — and precisely — integrated into a microgrid’s operations.

The existence of a generator at a facility can also cut down on solar + storage installation costs in some cases because the facility may already have a transfer switch, or potentially even electrical wiring with subpanels for critical loads. The existence of the battery allows you to run the generator at full throttle (at a fixed output), instead of ramping up and down to meet loads, because any excess generation can be stored in the battery. This allows the generator to run most efficiently and for shorter periods.

For many of us, any carbon emissions are unacceptable. Thus we have an immediate concern about the use of generators. Our concerns are elevated when it comes to making investments in infrastructure that supports a fossil-fueled power structure. But here’s a means to maintain the highest levels of reliability in a solar + storage microgrid, for hospitals, police facilities, and other critical facilities. Generators allow for these levels of reliability without incurring inordinate battery storage costs. Thus a case can certainly be made that the infrequent and precise use of a generator can make tremendous sense.

Microgrids 1.9: Microgrid Perspectives

Peter Asmus, Research Director at Guidehouse Insights, has been tracking the development of microgrids for over a dozen years. He’s written 100+ articles on microgrids. In a recent episode of The NetPositve Podcast, he talks about the genesis of microgrids. For the most part, they originated out of necessity in the developing world. Many if not most microgrids in the world today are not connected to the grid.

But now, microgrids are coming of age in the “developed world” where there is a grid. They operate in parallel with the grid for resilience. Asmus noted that initially Europe scoffed at that concept because its grid was so reliable. But today, given extreme climate events throughout the world, including recent and devastating flooding in Europe, and thanks to dramatic drops in solar and storage prices, coupled with smart control technologies, microgrids make sense in many applications and locations. In some cases, they can pay for themselves through daily operations. They can be financed. Microgrids have come a long way.

In the podcast, Asmus talks about barriers to the implementation of microgrids. He characterizes the state of microgrids as “inching along to full commercialization.” He notes that yes, there’s lots of activity. Lots of microgrid projects are providing values. But he explains that microgrids are held back in some ways.

Deployment is still hampered to some extent by old-school, monopoly rules, like the “over the fence” rule. In most states, you cannot run a line over the fence and power your neighbor’s property. Not even during an outage. That will change in time.

Another factor at play is a utility culture inherently rooted and opposed to distributed generation and storage and by extension, microgrids. Differing rules and varying decisions on interconnection has challenged timely engineering and installation. The engineers that install and hookup microgrids say that we need to clarify and ease the interconnection process. Asmus notes that we are moving toward modular microgrid architecture, plug and play style, and all UL listed and approved, to make interconnection as smooth process.

Regulatory proceedings are underway, but policies are not yet set on how to fully capture the value of microgrids to society as a whole. Asmus explains that it’s not just the value of a microgrid to the winery, or warehouse, or wealthy homeowner, it’s also about community resilience and grid support. To spread the costs of microgrids, the multiple values of microgrids to the specific site, utility, and community need to become embedded in policy and ultimately in tariffs.

As of April 2021, and according to Microgrid Knowledge, lawmakers in 20 U.S. states had introduced 69 microgrid-related bills in legislatures. This has been driven by the need for grid modernization, energy resilience, and by extreme weather events, fires, floods, heat waves, cold plunges.

Barriers aside, there is great proof that there’s lots going on in the microgrid space. Asmus points to incredible technological advances in the years that he has been tracking microgrids: Solar costs are way down, storage costs are following a similar trajectory. Controls have dramatically advanced. Asmus says that they’re the key technology to making microgrids work, orchestrating sophisticated energy management protocols.

So, are we inching along, or are we charting a radically different power course? Perhaps some of each. To fully attain the value of microgrids, based on currently available technology, we need to move faster. No more mobile generators (Morbugs), mostly diesel, to respond to climate-induced harsh realities and PSPS events. We need clean energy resilience. We need modular and carbon-free solutions. Easy to permit and to interconnect. We need to be able to finance these systems and their values for “energy as a service” and “resilience as a service.”

Microgrids 1.10: The EcoMotion Challenge

This is the tenth in our ten-part series on microgrids. Let’s end up discussing the challenges and opportunities related to our current work building microgrids in California. Teaser… they must be carbon-free and fully financed!

We began the series by defining microgrids, their history and their now ever-so-popular ability to island from the grid and provide resilience in the event of a grid outage. The series delved into microgrid components… solar, storage, and controls. We checked out case studies in far-flung places like the Bronx and Mendocino County. We described EcoMotion’s first microgrids in Monterey County, telling the Santa Rita story. We focused on critical loads. Another article featured giving batteries “a day job.” One article highlighted potential synergies — and compromises — with integrated generators. We delved into interconnection and the state of microgrids from a macro and regulatory perspective with Peter Asmus.

Right now, EcoMotion is helping to develop microgrids on behalf of two Community Choice Aggregators (CCAs) here in California. The goal is energy-resiliency. For Clean Power Alliance (CPA), we have evaluated over 120 sites in over 20 cities for carbon-free energy resilience. Cities nominate sites that they would like to see “hardened.” We’re looking for sites that meet our “ideal site checklist” of 12 parameters, for instance, significant load that can be offset with significant solar. We dig into load profiles and interval data. We model systems. In cases, solar generates savings when coupled with a rate shift… savings that we redirect to batteries and controls. The financial equation includes modest savings from peak clipping and arbitrage.

When a site looks good, our engineering team digs in onsite. We begin with the electrical switchgear: Is it sufficient to land solar + storage? Does it need to be replaced? We use single lines to determine where the critical loads are and how they are wired. For each site, we explore subpanels, and smart panels that allow for critical load and full solar configurations. (When the sun is shining, many of our sites will be able to power much more than their critical loads.) Our team examines structural and roofing conditions, conducts shading analysis, and considers conduit runs. We look at spatial opportunities for solar-ports and where storage can be located.

For each site, we build a dossier. We capture photos and videos in an app called Fulcrum, which also houses drawings and data. We write a four page “Site Narrative” that provides an overview of each site, the system planned, the loads to be backed up, and thus the use case at hand. In the coming weeks, we’ll have more than 20 sites ready to go, assembled into a portfolio to be taken to market. Just like a solar system fully financed through a power purchase agreement, we’ll be reaching out to our primed network of suitable developers that will own and operate all the microgrid equipment for the next 20 years.

East Bay Community Energy (EBCE) serves 14 cities and unincorporated parts of Alameda County. These 15 member agencies want resilience in public buildings… in some 300 public buildings. So far, our work with EBCE has focused on two cities’ public buildings, Berkeley and Hayward. For these evaluations the EcoMotion solar team is joined by Point Energy Innovation’s engineers, KPFF structural engineers, and Blue’s Roofing experts. We’re doing deep dives at each site, developing a roadmap for making these facilities functional during grid outages.

For both CCA projects, EcoMotion’s job is to ready a portfolio of energy-resilient buildings to take to the market. What will these microgrid systems cost? How much will they save? Can we get energy resilience without incurring additional costs? That was the case at Santa Rita. Or will certain sites bear a cost premium with the resiliency adder? Yes, EcoMotion can find sites that can switch from being totally dependent on the grid, to having microgrid capabilities, at no additional cost. But these are choice sites that meet many ideal site parameters and that are eligible for rate changes. Microgrid prices will go down, but in most cases energy resilience will bear a cost. How much is a design issue that we will continue to report back to you.