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New Law Requires Solar on NYC Buildings

You may have heard about New York City's new Climate Mobilization Act, but did you know that it includes a requirement to install solar on many NYC buildings?

In April 2019, the New York City Council passed the Climate Mobilization Act: a series of local laws that will dramatically reduce greenhouse gas emissions from New York City’s buildings, which are responsible for 67% of the City’s carbon footprint. The law that received the most attention was Introduction 1253-C, which will establish limits on carbon emissions for buildings greater than 25,000 square feet, driving these large buildings to reduce energy consumption or purchase carbon offset to avoid hefty fines starting in 2024. The bill’s final details were hotly contested by the real estate industry, making for a political showdown that received significant media attention. Meanwhile, the City Council also passed a solar (or green roof) mandate which flew under the radar but goes into effect this year and covers even more buildings! 

Read more +


Announcing Sunset Park Solar

Here Comes Solar is thrilled to announce that we and our partners were selected by the New York City Economic Development Corporation to develop Sunset Park Solar, a 672 kilowatt-DC community shared solar project on the roof of the Brooklyn Army Terminal.

The project will be New York City’s first community solar project owned and operated by a cooperative for the benefit of local residents and businesses. The project team includes Solar One, UPROSE, Co-op Power, Resonant Energy and 770 Electric Corp. This project is an embodiment of UPROSE' vision for community-owned renewables in Sunset Park. The system will be installed by a local workforce including job trainees, and the system will be owned by Co-op Power's NYC Community Energy Cooperative and UPROSE, a Sunset Park-based environmental justice organization.

Read more about the project in this Fast Company article or visit the project's bilingual (Spanish/English) website sunsetparksolar.org to sign up!


What’s So Fun About Batteries?!

Chapter V. Grid is Great

"The energy storage revolution will abandon today’s boring, antiquated, mostly uni-directional grid for the dynamic grid of the future."

Well, it’s been a while. I’ve been terribly negligent, haven’t I? My apologies. Damned Sisyphus changed the blog’s login credentials without telling me. The mutinous monarch had grand designs for a blockbuster series of posts on his locomotive exploits, titled – what else? – The Fast & The SisyPhurious.

There was even a poster:



What a dork, huh?




Here at WSFAB, we’re often asked, “How can I go off-grid?”

Our answer, more often than not? “Please don’t.”


In the popular imagination, energy storage is all about quitting the grid. Indeed, since the rise of solar photovoltaics a few decades ago, lead acid batteries and solar have made a great pair in remote areas. With the solar powering loads and charging the battery for night-time use, a well-designed, off-grid solar + storage system can provide clean, reliable electricity 24/7.


So, what’s the problem? For remote installations, there isn’t one. Wherever you are, it is costly to connect a house (or any other electric load) to the grid, but these interconnection costs skyrocket the farther you get from dense webs of distribution wires. This isn’t surprising. Where there is little infrastructure ready to serve a new load, and new wires must run long distances to reach that load, interconnection gets pretty pricey. The pricier it gets, the more attractive off-grid solar + storage becomes. But – if you are close to the grid, it’s probably cheaper to go with grid-tied solar and pull power from the grid at night.


Here’s the cost comparison in its simplest form:

Off-grid solar + storage cost = Solar and storage installation cost + storage replacement cost (if necessary)


Grid-tied solar cost = Solar installation cost + interconnection cost1


If your home is a sylvan backwoods cabin or a sun-dappled island bungalow, going off-grid could very well be the cost-effective choice. But such cases are hugely outnumbered by those for which grid-tied solar is the cheaper option. And believe it or not, off-grid solar + storage is often less environmentally friendly than grid-tied solar. This is because no battery is perfectly efficient at charging and discharging – about 20% of the energy with which it’s charged will be lost by the time it’s discharged.2


The gist? In broad strokes, energy storage is reinventing the way we generate, deliver, and value power. But unless you’re out in the middle of nowhere, off-grid solar + storage is typically less cost-effective than grid-tied solar. And that’s fine! Because there are plenty of other reasons to add batteries to grid-tied solar, and if we want to build the dynamic grid of the future, we’re going to need a lot of batteries on the grid.




Batteries have many flattering traits. Most flattering of all is the load “flattening” they can provide to the grid, by charging when the load on the grid is light, and discharging when it’s heavy. This helps shift solar power to night-time, wind power to low-wind-time, and excess power of all kinds to peak-time. All three of these power-shifting behaviors can drive down electricity costs for utility customers and significantly reduce carbon emissions.3


You don’t have to run the Hoover Dam or Grimes' boyfriend's Australian apparatus to contribute - there are many ways in which a more modest grid-tied energy storage system can get paid to flatten loads. Better yet, such batteries can multitask. That is, they can smoothly alternate between different behaviors, maximizing usefulness and profitability. This is known as "value stacking."


Check out all of the fun values in this stack!


  • Demand charge reduction - A customer with a monthly peak demand above 10 kW pays a "demand charge" that increases with the size of their peak. A battery can flatten the curve by discharging during peaks, thereby lowering their bill. This is the simplest revenue-generation method for behind-the-meter batteries, since it doesn't require registration for any utility or agency energy programs.
  • Rider Q - Under Con Ed's Rider Q tariff, a customer can opt into a rate with daily kW peak and off-peak hours. The customer then pays demand charges if they consume during peak hours, but is no longer charged for a monthly kW peak. A battery can generate significant savings by charging off-peak and discharging on-peak.
  • Demand response - Demand response generates value for the utility by flattening kW peaks at the distribution level. Operationally, it's a lot like demand charge reduction, except that it targets peaks on the grid instead of at a customer's meter. Depending on a battery's size and availability, it can participate in several different Con Ed demand response programs.
  • Load shifting / Energy arbitrage - If a customer pays variable time-of-use rates, their battery can charge when energy's cheap and discharge when it's expensive, helping the customer avoid peak kWh pricing. This is called "load shifting." Energy arbitrage is similar, except the battery sends power to the grid during peak hours, maximizing the rate it's paid for energy exports. Right now, energy arbitrage has uncertain regulatory support, but it's likely to be viable soon.
  • Non-Wires Alternatives (NWA) - By performing load-flattening much like that required by demand response, a well-placed battery can obviate the need for grid transmission and distribution upgrades. Con Ed will pay installations that reliably provide these services. NWA programs are very likely to become more prevalent and accessible as distributed energy resources proliferate in Con Ed territory and new transmission and distribution upgrades become necessary.


Admittedly, if you're new to this stuff, this might feel less like a nice, neat "stack," and more like a Jenga tower. But everybody's pretty new to this – you're ahead of the game just for getting this far!


Here’s the thing. Sure, “off-grid” sounds rugged & sexy – but the grid needs our help if it’s going to grow into the cleaner, more dynamic grid of the future. An ever-expanding fleet of small, behind-the-meter batteries are going to be essential to this transformation.


Conclusion? Grid-tied is sexy, too. 😉




What’s So Fun About Batteries?!

Chapter IV. One must imagine Sisyphus happy.

"The energy storage revolution will finally enable the transition to a majority-renewables grid."


“…Sisyphus teaches the higher fidelity that negates the gods and raises rocks. He too concludes that all is well. This universe henceforth without a master seems to him neither sterile nor futile. Each atom of that stone, each mineral flake of that night filled mountain, in itself forms a world. The struggle itself toward the
heights is enough to fill a man's heart.
One must imagine Sisyphus happy.”

– Albert Camus, The Myth of Sisyphus


Myth is right! Imagine me happy? Indeed, that requires some imagination, Albert.

How could I find joy in fruitless labor? I imagine you writing your essay, Albert, if each sentence were to fade from the page the moment you came to a full stop. You would never complete a work, let alone a word. You would create nothing, contribute nothing. Yet you expect you would find joy in this arrangement?! I have my doubts, Al.

But fret not, dear reader! This Corinthian King’s labors have, at long last, borne sweet fruit. I have found rapture in my repetition, transcendence in my trudgery. No longer do I serve a démodé deity; today, I serve The Grid.


Things seem to have changed a bit since I began my ascent several millennia ago.

Among these things:

        1. Nobody worships Zeus and his ilk any more (HA!)
        2. Monarchy is pretty passé now 😢
        3. Sometimes, people brush their teeth
        4. Regenerative braking is a thing

…and that about covers it!

Today, I would like to focus on by far the most thrilling of these developments. If you drive a Prius, you probably know about regenerative braking (“regen”); if you don’t, then you probably don’t. But it’s not just for Prii – regen was first patented in 1907, if not earlier. But what is it?



First, consider a traditional, non-regen vehicle. When you pump the brakes, friction is applied to the wheels, converting their kinetic energy into thermal energy. In this process, none of that kinetic energy is destroyed – you and your vehicle just cannot harness it in its new state as “waste heat.”

Instead of applying friction to the wheels (as in traditional braking), regen slows the vehicle simply by cutting power to the motors that turn the wheels. The wheels’ kinetic energy then flows back to the motors, using them as electrical generators to recharge the battery. In other words – when accelerating, the battery powers the motors, which turn the wheels; when regenerative braking, the process is reversed, as the wheels power the motors, which charge the battery. Regen cannot slow a car as rapidly as traditional braking can, so at greater speeds, the vehicle must supplement regen with friction, causing the loss of some kinetic energy as waste heat. But in a modern regen car, about 70%-80% of the wheels’ kinetic energy can be captured and used to recharge the battery. The other 20-30% is lost to standard inefficiencies in the lithium-ion battery charge/discharge process.

You’re probably wondering, “Who cares? What, does Sisyphus have a Prius?!”

Of course I don’t! Even the unusually spacious Prius hatchback can’t accommodate this (literally) damned rock.1 No – I am the founder and CEO of Sisyphus Storage, the world’s finest boulder-based energy storage firm. As ever, I shoulder my boulder, but now the ignominious ingot sits in a railcar outfitted with regenerative brakes. When grid operators need electricity stored, I mainline the stuff, supercharging my ascent.2 As I near the summit, I lock the car to the tracks. Thus, the electricity fed into the motor (my body) has been converted into gravitational potential energy. When grid operators need to draw power from this “battery,” I unlock the car from the tracks, hop atop my boulder, and speed downhill.

Choo choo! What now?

        1. Gravitational potential energy is converted into kinetic energy, driving the wheels downhill;
        2. Regenerative braking is applied, feeding kinetic energy into motors that convert it into electricity;
        3. Electricity is sent back to the grid;
        4. We slow to a gentle stop at the bottom of the decline. The battery has been fully discharged.



But… why do any of this? It’s not like you’re actually generating any new electricity, right?

That’s right – I just take electricity from the grid and hold onto it for safekeeping. But this is an extremely valuable service! Grid operators call on me to charge and discharge electricity for all sorts of reasons. Most of the time, they ask me to store excess electricity from wind and solar farms. Since these energy sources aren’t "dispatchable,"3 they’ll often produce more (or less) power than what customers need at a given moment. Any electricity beyond what’s being demanded by customers has to be safely sent somewhere – this is so vital that sometimes a utility will actually pay a neighboring utility to take its excess power! You won’t be surprised to learn that for-profit corporations don’t particularly relish this scenario.

That’s where I come in. The utility instead pays me to take its excess power, which I use to hustle up my hill. Then, the next time their renewable power plants are under- instead of over-generating, I send my stored energy back to the grid. Voila – we’ve turned the wind and solar farms into dispatchable resources, like traditional natural gas power plants. Of course, my battery is slower-moving than the lithium-ion ones that rule the market – those nimble little guys are great at responding to second-by-second fluctuations in electricity demand and supply. However, I can hold a charge a whole lot longer than they can. Once I’m charged, I can sit on my hilltop perch indefinitely. I can even hold excess solar power from the summer and save it for the shorter, dimmer winter days. Such “seasonal storage” is going to be absolutely vital if we’re ever going to build a majority-renewables grid.

This is all to say - you don’t need a chemical battery to store energy. In fact, depending on your needs, you might prefer to pay a damned, immortal monarch to shove a boulder up a hill. I'm just happy to d-


Ah, a demand peak! My apologies, but I've got to shove off - duty calls.




What’s So Fun About Batteries?!

Chapter III. OMG, Batteries Are so Fun. Can I Get One?

"The energy storage revolution will grant individuals unprecedented control over their energy profiles."

Welcome back, Friends of WSFAB! Apologies for the delay between chapters. Angelica, Richard, and I have been pretty busy with our day jobs – working with the Governor’s Office of Storm Recovery (GOSR) to deploy solar + storage systems1 at community organizations around NYC. If you want to get really wonky, check out our first four sites!

We’ll talk more about the GOSR work soon – it’s exciting, groundbreaking stuff. But for now, please admire your friendly neighborhood energy geeks as they cool off between site walks at Birch Family Services:

We listen to our fans here at WSFAB. Here’s some feedback we’ve received from our treasured readers.

          • “Honestly, I really doubted the premise of this series. Like, they’re batteries, okay? They’re not fun. BOY was I wrong! Resilience?2 Demand charge reduction? DOPE! Gimme batteries.” – Shane, 24
          • “Before I was a WSFAB subscriber, when I heard the word ‘battery,’ I thought of depleted cell phones. Now? I get so amped that I can’t think straight. It’s actually a little scary.” – Dolores, 36
          • “OMG, batteries are so fun. Can I get one?” – Glenn, 7


I feel the same way, Glenn. The answer is… maybe! Let me explain.

Why would you want a battery in your home?

For most people, the main appeal of a residential battery is its ability to provide backup power. If you pair it with a rooftop solar array, you can even recharge the battery day after day during an extended blackout, so you’ll have power when the sun’s not shining.3 You don’t need me to explain why you’d want backup power during a blackout. But big batteries tend to be expensive – certainly pricier than equivalent diesel generators. Why go with the more expensive option?

Demand charges.

But before I explain what these are, let’s talk about power.

A “kilowatt” is a unit of instantaneous electric power. A lightning strike, for example, carries about 10 million kilowatts in a given moment.4 This isn’t a terribly useful metric for measuring your electricity consumption at home, though, since you (hopefully) never need nearly that much power at any particular instant. Instead, you draw far less power, but you draw at least some of it every second of every day. Therefore, you pay your electric utility by the “kilowatt hour” (kWh). A kilowatt hour is, you guessed it, a kilowatt of power exerted over the course of an hour.5 A kilowatt hour represents a volume of electricity consumed – you pay for kilowatt hours of electricity at home just like you pay for gallons of gas at the pump.

If you consume enough electricity, though, your utility will start billing you for kW in addition to kWh. Why? Because if you draw a lot of power in a split second – a “peak” in your consumption – they have to make sure they can provide all of that power instantaneously. If many customers peak at the same moment, the utility might need to rev up another power plant to provide enough power. To meet these needs, utilities bill their peakier customers “demand charges” by the kW. Every month, they bill each of these customers for their highest kW peak.


I’m sorry, I know this is a lot. The good news is, if you live in an apartment or a small house, you probably don’t need to worry about demand charges on your personal bill. But if you live in a large apartment building, the building itself probably does pay demand charges for its common area loads. These typically include lighting, heating, and air conditioning in hallways, laundry rooms, etc., plus elevators. If your building pays demand charges on its common area bill, then I’m happy to report, Glenn, that maybe you can get a battery!

Batteries are excellent at reducing demand charges. They do this by charging up when your building isn’t using much power, and discharging when your building needs lots of it. (A battery can charge up either from an onsite solar array or directly from the grid.) This can dramatically lower your building's monthly peaks, leading to much cheaper electricity bills. In this scenario, a battery might be a fantastic investment.

But how can you tell whether your building fits the bill? Let's get into specifics.

A good energy storage candidate:

      • Pays demand charges ($/kW), in addition to supply charges ($/kWh), on its common area electricity bill. If a building's "SC" (Service Classification) on its Con Ed account is "EL" (Electric) 5, 8, 9, 12-demand, or 13, you know it pays demand charges. In NYC today, the only easily-accessible revenue stream for a battery is demand charge reduction. Generally speaking, if a battery can't do demand charge reduction, it can't pay for itself.
      • Has 200+ square feet available, either on a roof in good condition, in another outdoor space, or in a noncombustible indoor room. Lithium-ion batteries, the most versatile type currently on the market, cannot currently be sited indoors in NYC, so rooftop or other outdoor space is ideal. (If the plan is to power an elevator for multiple days, well over 200 square feet will be needed, unless the project includes solar.) However, advanced lead-acid batteries are nearly as useful, and can be sited in noncombustible indoor rooms.


If your building meets both of the above requirements, let's talk! With utility data and some layout details, we can quickly estimate the size and type of battery you would need to meet your resilience needs, while still providing profitable demand charge reduction.

...but let's not forget about solar.

After confirming that your building pays demand charges and has a good spot for the battery, the big remaining factor is your solar potential. The usefulness of solar to a battery depends on a few factors - most importantly, the size of your building's critical load6 compared to the size of the battery. If the daily critical load is nearly as large as the battery's capacity, the battery will only be able to power the building for roughly one day. To maintain power during an extended blackout, this building would need to add solar so it can recharge its battery day after day.

Plus, adding solar to the project will likely improve the quality of the investment, both because solar has a quicker payback period7 than batteries in NYC, and because tax benefits on the solar can be extended to the battery if they're deployed together. In other words, while solar is not always essential to a resilient battery installation, it really helps. So if your building meets the two battery viability requirements above, please also keep its solar potential in mind.

Believe it or not, I’ve skimmed over many important details here, but my spiel is already overlong. If you have any questions - or, better yet, building candidates! - shoot me a message at derek@solar1.org or on Instagram at @ResilientNYC.

Be sure to check in on WSFAB next week, when we'll welcome a very special guest columnist. He'll walk (trudge? heave?) us through some of the more whimsical methods of energy storage...


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