Related blog posts

This post is self-contained but it is related to some earlier posts:

• An Introduction to CCAs, IOUs and POU

• A discussion on the Impact of Time and Location on Electricity Costs

• Background and discussion of the Extended Day Ahead Market (EDAM)

• A handy Glossary

What are Energy Markets (Energy 101)

Roy Xu’s segment presented the basics of Energy Markets. His presentation starts at Slide 19; the recording starts here.

Roy and Justin Kudo followed up with a presentation on Managing Volatility. That segment is more technical and it even explains what PCIA is. I may do a second post on that content at some point later.

Power > Grid > Customer

Electricity goes from a power source, through the grid, to customers. 90% of PCE’s budget is spent on procuring electricity for its customers.

The Customers - The Load

PCE will purchase power to satisfy the needs of its customers. The electrical consumption (called load) varies by day, hour and season. Here is a graph of the average consumption of PCE customers over 4 quarters:

The Grid

Our grid is the Western Interconnection (WECC).

The WECC coordinates a number of high voltage power links:

At any time, the grid has to be balanced: load has to equal generation. In addition, physical elements like wires and transformers limit how much power goes between specific locations at specific times. The WECC operates the larger grid, while a Balancing Authority (BA) is responsible for operating a portion of the grid. PCE is within the CAISO BA.

Power Sources

PCE buys most of its electricity ahead of time, through Power Purchase Agreements (PPA). The PCE page on power sources is easy to navigate and shows projects like Chaparral (15-year, 102MW solar, 52MW 4h storage), Lockhart (15-year, 45MW 4h storage) and Wright Solar (25-year, 200MW solar).

PCE tries its best to estimate correctly the energy needed, and then securing it through PPAs, but delivering the power involves a market.

How does a Market Operate

A market is needed because

1. PCE can’t predict the needs perfectly; it needs to make adjustments “at the last minute”, and

2. The capacity of different paths in the grid varies continuously

So what really happens is that PCE sells the energy into the market at one place and buys it at another place.

Here is the example from Roy’s slides:

In this example, PCE need 100 MWh for its customers (in San Mateo County and the City of Los Banos). PCE buys this energy from the market (operated by CAISO), in this case at $100/MWh. At the same time, PCE will sell 100 MWh to CAISO at $90/MWh. The energy PCE is selling comes from a PPA where the price was set at $40/MWh.

Adding all up, the total cost to PCE for the 100MWh is $10,000 paid to CAISO + $4,000 paid to the power developer via the PPA - $9,000 received by CAISO = $5,000. The existing PPA is saving PCE $5,000 over buying the electricity on the spot.

Really Two Markets

Actually there are two markets, the market mentioned above is the Real Time Market, the Western Energy Imbalance Market (WEIM). There is also another market, the Day Ahead Market (DAM), where PCE can buy, and sell, electricity for the next day.

The full process then is, estimate the “long term” needs and purchase PPAs. The day ahead, buy/sell based on needs/availability at DAM, and during the day, in real time, buy/sell on the WEIM market.

DAM operates only within CAISO’s BA, while WEIM extends beyond CAISO to other entities in WECC. An Expanded DAM, EDAM, brings additional benefits and it is an ongoing topic of discussion.

Impact on Renewable Energy

Roy has a great slide showing where PCE energy came from in 2021 (left) and 2024 (right) through a day. The grey bar shows electricity bought in short-term transactions, the rest is from PPAs. The slide shows the progress made in 3 years — and it also shows how batteries are starting to play a role in PCE’s source mix.

The gap between long-term plus short-term resources and the load is what has to be bought in the WEIM. In the case of 2024 above, it is the small area in white:

Added correction (on May 2, 2025; thanks to Roy)

On any particular day, the open positions (white space) could be filled with purchases from either the DAM or the RTM (WEIM) depending on our bidding strategy and how the markets clear.

Products, Procurement Types and Channels

The last two slides from Roy’s presentation cover the types of energy products purchased, and how they are purchased. Each section is worthy of its own presentation.

The types of products are:

• Energy - this is what we have been covering so far.

• Resource Adequacy (RA) - generation capacity for load plus margin

• Mid-term Reliability Order (MTR) - reliability support given growth

• Renewable Energy Credit (REC) - 1MWh of delivered renewable energy

• Carbon Free Attribute (CF) - 1MWh of delivered carbon-free energy

Different types of resources can be used to acquire different products. For instance, Lockhart provides resource adequacy (RA), ancillary services (like frequency regulation), and energy arbitrage (buy energy when it is cheap and sell when it is more expensive)

Roy next described very briefly the types of procurements than can be used to acquire the above resources: Long-Term Bundled Transactions: Request for Offers, Bilateral Engagements, Joint Procurement through CC Power and Short-Term Product Transactions

PCE Priorities

Roy’s final slide captures the PCE’s Procurement Puzzle: what strategies to use on the Products and Instruments to achieve the PCE Priorities

We have already talked about the first two priorities: serving the loads of PCE’s customers and complying with regulations like those from CPUC, CAISO, and the California Legislature (like RPS). ECO Plus and ECO 100 are the PCE’s consumer products and they have specific energy requirements. 100% Renewable Energy on an annual basis is a priority, and so is having a financially stable corporation and delivering energy to the customers with affordable rates. PCE still wants to deliver 100% Renewable Energy on a 24/7 hourly basis but achieving this in the context of all the other priorities has proven harder than expected.

Additional Pointers

Some very quick pointers to more details.

If you look carefully at Roy’s slide of the market transaction you will see that the sell transaction mentions a p-node while the purchase transaction mentions a DLAP. . Both terms are defined in the CAISO Glossary and are relevant to the CAISO Tariff, and its LMP - Locational Marginal Price. PNode stands for Pricing Node; DLAP stands for Default Load Aggregation Points

The Full Network Model from CAISO has a lot of details about CAISO’s grid. The document is an XLS file with extra details and it includes a map of the CAISO grid that renders best on MS Excel but it renders OK on Google Sheets.

The CAISO website has plenty of good information and the pages on Todays Outlook provide information on Supply, Demand, Emissions and Prices. Here is the Supply Trend for April 23, 2025

Finally, GridStatus has a great dashboard for CAISO. The Import/Export widget shows that, on April 22, 2025, CAISO exported between 7:25 am and 6:15 pm.

Enjoy exploring the websites!

The Electric Grid in California

The Electrical Grid has been described as the world’s largest machine, and, as such, there is a fair amount of background involved. Below is a quick pass through the basic terms needed to talk about the map. If you are familiar with the concepts, you can skip through them.

Mini-History

The current landscape is the result of several historical trends.

In the early 1900s California (and the US) had a large number of small electrical companies. Over time we saw consolidation and the creation of big for-profit corporations like PG&E, but there are still many public utilities around. The late 1990s saw the deregulation of the California energy market (AB-1810, 1996), where generation was separated from distribution (and retailing), and later, in early 2000s, the emergence of Community Choice Aggregators.

Today’s landscape has many stakeholders and this will continue to evolve as we see more distributed energy resources in front of, and behind, the meter, and through Virtual Power Plants (see FERC 2222).

CCA - Community Choice Aggregation

AB-117 (Midgen, 2002) created the legislation that enabled community-led non-profit Community Choice Aggregation (CCA) programs to form in California (CalCCA mini-documentary, Wikipedia). Through Community Choice Aggregation, communities can join together to pool (or aggregate) their electricity load in order to purchase clean energy and develop local projects and programs on behalf of their residents and businesses. Aggregators work in partnership with the region’s existing Investor-Owned Utility (IOU), which continues to deliver power and maintain the grid. Two or more cities or counties may participate in a CCA program as a group through a Joint Powers agency. A CCA can also be formed by a single city, such as those operated by the cities of San Francisco and San Jose.

A CCA’s main role is to aggregate power sources and provide them to the customers in their territory. The power is often from renewable sources and it is provided at a lower cost than other alternatives; also see this note.

IOU - Investor Owned Utility

California has several for-profit Investor Owned Utility (IOU) that cover much of the state. The IOUs still service most of California through their ownership of the transmission and distribution grid, the meters, and the retailer relationship.

When a customer signs for a CCA, the CCA provides generation that uses an IOU to distribute the power to the customer. The bills come from and are paid to the IOU.

POU - Publicly Owned Utilities

Publicly Owned Utilities are non-profit and, unlike CCAs, they own the distribution grid and the retail relationship with their customers.

Many of the POUs are old; check out the California Municipal Utility Association and its history.

Load Serving Entity

A Load Serving Entity (LSE) is a company or government agency that is obligated by law or via a long-term contract to provide electrical power to end-users. CCAs, IOUs, POUs are Load Serving Entities. So are Rural Coops and some other entities.

And… a load is anything that consumes electricity, like our heat pump inside our house, or a big industrial electrolyzer.

Balancing Authority

A Balancing Authority is responsible for grid balancing, which including matching production and consumption. The balancing authorities are connected by metered high-voltage tie lines and grouped into interconnections.

WECC - The Western Interconnect

The Western Interconnect is a wide-area synchronous grid. Generation and Load in the interconnect has to be balanced very closely at all times. Synchronous grids are connected to each other through high voltage DC lines.

The CCA Map

And now we can go back to the CalCCA Map!

The CalCCA map shows all the CCAs in California, as well as the POUs and IOUs. The map supports navigation and search and it also includes information on the number of customers and the power from each load serving entities.

Below is a screenshot showing all the CCAs. There are 25 altogether, many more than I expected. Some are small, some are very big.

I found the map content very interesting and I started capturing details in a side spreadsheet. That ended up growing into this post…

Other Maps and Resources

I used additional data for this post including:

• California Open Data project collates many sources. A search on “electricity” delivers 100 datasets; one on “electricity cca” delivers two datasets.

• The California Energy Commission has multiple datasets. Here is the page on Electricity Data, and within it, a page on Load Serving Entities.

• The Energy Information Administration has a plethora of data.

Consolidated Spreadsheet

I created a spreadsheet from the CalCCA map (plus this table) with data for each entity, including the type, retail sales in GWh, number of accounts, and balancing authority. The project ended being a nice expedition through California, from coastal communities to irrigation districts:

• Consolidated data sheet

Exploring the datasets

CCAs

Here are some interesting CCAs, with sales and customer data (as of December 2023) from the CCA map:

• The first CCA in California was Marin Clean Energy (MCE) which began service in May 2010. MCE has 5,624 GWh in sales and 586,296 customer accounts.

• The most recent CCA to launch service is Energy for Palmdale's Independent Choice (EPIC), in October 2022. EPIC has 444 GWh of sales and 46,470 customer accounts.

• Peninsula Clean Energy is the CCA for San Mateo County, where we live, and the City of Los Baños. PCE was formed on February 2016. PCE has 3,392 GWh of retail sales and 310K customer accounts.

• San Jacinto Power is the CCA for the City of San Jacinto. They have sales of 172 GWh and 15,087 customer accounts

• Clean Power Alliance is the CCA for 33 cities in SoCal, and the unincorporated areas of Los Angeles and Ventura Counties. CPA has sales of 10,540 GWh, and 1,006,961 accounts.

Together, the CCAs deliver 61,825 GWh to over 6 Million accounts.

POU

There are several types of POUs: city municipal departments, public utility districts, municipal utility districts, and irrigation districts.

Here are some examples of POUs:

• Los Angeles Water and Power Division (LAWPD) serves the city of Los Angeles and it is the biggest POU in the nation; it has 21,062 GWh retail and 1,465,281 customer accounts. It was founded in 1902 and it started providing electricity in 1917.

• Silicon Valley Power (SVP) serves the City of Santa Clara. SVP was founded in 1896 and it has 4,479 GWh retail sales, and 60,685 electric accounts.

• Sacramento Municipal Utility District (SMUD) is a more recent POU. It was created in 1946, after an intense battle with PG&E. It has 10,529 GWh retail sales and 643,363 accounts.

• The Turlock Irrigation District (TID) was founded in 1887 and it is the first irrigation district in California. It has 2,268 GWh and 94,839 customer accounts.

IOU Territory

The map below shows the IOUs territories. Recall that customers that choose a CCA within an IOU territory get the electricity from the CCA.

There are six IOU in California:

• Pacificorp (Wikipedia, Corporate) started as Pacific Power and Light in 1910 in Oregon and Washington and later expanded into California. In 1984, it reorganized itself as PacifiCorp. Pacificorp has a very large transmission system. It delivered 800 GWh of retail sales with 2,002,779 accounts. Its territory is 6,178,184.98 Acres.

• PG&E (Wikipedia, Corporate) incorporated in 1905. After large wildfires caused by its electrical lines, PG&E entered bankruptcy in 2019 and it exited it in 2020. It delivered 28,168 GWh retail sales with 2,269,282 accounts. Its territory is 42,685,909.55 Acres.

• Liberty Utilities (Wikipedia, Corporate). Liberty Utilities is part of Algonquin Power & Utilities Corp. It delivered 564 GWh retail sales with 49,539 accounts, 938,671.41 Acres. Its territory is around Lake Tahoe. Unlike the others, its Balancing Authority is NVE (Nevada)

• Southern California Edison (Wikipedia, Corporate). SCE also has history with Pacific Power and Light in the late 1800s and early 1900s (details). It delivered 49,598 GWh retail sales with 3,881,200 accounts. Its territory is 33,110,278.13 Acres

• Bear Valley Electric Service (Wikipedia, Corporate). It delivered 131 GWh retail sales with 24,596 accounts. Bear Valley Electric’s territory is fairly limited, around the Big Bear valley in the San Bernardino Mountains.

• San Diego Gas and Electric (Wikipedia, Corporate). It was founded in 1881. It delivered 5,195 GWh retail with 1,394,365 account and a territory of 2,634,141.98 Acres.

Some more Statistics

Comparing IOUs and CCAs

To compare CCAs and IOUs one should clarify what is being considered. As mentioned at the beginning of this note, the main role of CCAs is to aggregate power and make it available to consumers. CCAs do this within specific jurisdictions which are in territories served by IOUs, and these IOU deliver the energy through their distribution lines and meters, and invoice and collect from the customers.

In a very real sense, any CCA customer is also an IOU customer, but a CCA customer does not “buy” electricity from the IOU, “just” pays for the distribution of that electricity. The numbers listed under “electricity accounts” in the CCA Map, in my spreadsheet, and at the end of this section, all use a narrow interpretation of electricity account, and a CCA customer in an IOU territory is counted only in the CCA category, not in the IOU category.

In our personal case, our household purchases generated electricity from Peninsula Clean Energy but we pay through PG&E. Actually, since distribution is around 60% of the total energy bill, most of the bill goes to PG&E. Despite this, I consider myself first a PCE customer, and I have a relationship with them.

Using my spreadsheet, we can summarize as follows (caveat: POUs are undercounted as I only have data for some of them):

Delivered Electricity (GWh): IOU 84,456 | POU 55,730 | CCA 61,825
Electricity Accounts (M): IOU 9.621 | POU 2.912 | CCA 6.088

Using these two metrics, POUs + CCAs are comparable or larger than IOUs, though IOUs currently carry much larger political cloud in California.

IOU Delivered Electricity

The CEC datasets do not track delivered electricity after 2020. The CCA Map has a values for the CCAs for late 2023, and for IOUs for 2022. I do not know if the two datasets are fully comparable but there has a been a substantial transfer of electricity generation from IOUs to CCAs. Even if the shape of the curve is not fully correct, the initial and end points should be accurate since the data points in 2010 predate all CCAs and the final data points in 2023 should be the latest data.

Balancing Authorities

There are multiple balancing authorities that work within the Western Interconnect to maintain the health of the grid. I mostly knew about CAISO, but there are a few others.

• CAISO - All IOUs but one Liberty Utilities, all CCAs, and most POUs use CAISO.

• NVE - Liberty Utilities uses the Nevada Energy as its Balancing Authority.

• LAWPD - Several POUs in the LA area use LAWPD as their Balancing Authority.

• BANC - This is a Joint Powers Authority (JPA) Balancing Authority; it is the third largest Balancing Authority in California! SMUD and several Irrigation Districts use it.

The Largest

• IOU with the most accounts? SCE, with 3,881,200

• POU with the most accounts? LAWPD, with 1,465,281

• CCA with the most accounts? CPA, with 1,006,961

More Posts… Later

I learned a lot writing this post. I hope to continue to write more content in the future, as I learn more. In the meantime, look at the data in the spreadsheet and poke from there.