Security and Savings in Amazon VPC

In March 2016, Genability migrated its application servers and databases into Amazon’s Virtual Private Cloud (VPC). We initiated this change anticipating that it would not only provide hard security guarantees, but reduce our infrastructure costs without impacting performance. After a few months of close monitoring, the results are in: mission-critical resources are inaccessible to the public internet and we’ve reduced infrastructure costs by 50%, all while handling a tenfold increase in daily API traffic.


Established as a default in late 2013, AWS VPC allows users to create cloud resources which are “logically isolated from other virtual networks in the AWS cloud”. This has several advantages:

  • General and resource-specific control over incoming and outgoing connections
  • Access control rules which can be changed without stopping/starting servers
  • Persistent private IP addresses
  • Custom network interfaces

For Genability, this means we’re able to segregate our AWS resources into public and private subnets, isolate our production data, and establish fail-safe defaults which allow new resources to access what they need quickly and securely.

For accounts created before 2013, AWS also provides an incentive to make the VPC switch: access to the AWS T2 instance type.


AWS T2 servers “provide a baseline level of CPU performance with the ability to burst above the baseline”. This is great for most of Genability’s applications which, like most electricity grids, experience peak traffic which is substantively greater than the base load:

API traffic during a typical day

API traffic during a typical day

When traffic is low, T2 servers earn “CPU credits” which can be used when traffic is heavy to dynamically meet demand with the same level of performance. For Amazon, this means a more efficient use of their resources; savings they split with their customers.

Switching to the T2 instances, combined with some overdue AWS housekeeping, reduced our AWS costs to 50% of their 2015 average:

AWS cost breakdown

AWS cost breakdown

At the same time, traffic on Genability’s API increased tenfold:

API throughput March-April 2016

API throughput March-April 2016

What’s next: performance improvements aimed at reducing server-side response times by 30% to help us exceed performance expectations under increasing load.

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Accurate Savings Forecasts: California’s NEM 2.0 & Hawaii’s Customer Grid Supply



New regulatory policy and corresponding tariff changes in California and Hawaii mean more complexity in forecasting solar savings. Genability has you covered. We’ve added enhancements as part of Switch Version 4 to improve your savings analyses amidst these new rules. This includes new algorithms to determine how much energy is exported to the grid at any time during the day, all without any additional changes to your quoting platform or sales process.

Markets Potentially Affected by Dual Register Metering

California Investor Owned Utility (IOU) 

Encouraged by the existing Net Energy Metering (NEM 1.0) program, California has led the way in rooftop solar growth over the last few years. Under this program most Californians going solar receive full retail credit for energy their solar system exports to the electricity grid.

In January of this year the California Public Utilities Commission (CPUC) approved the framework for a successor to the existing NEM 1.0 program, referred to as NEM 2.0. This will roll out to new solar customers over the next year as each of the three California IOU utilities reaches its existing program cap. With NEM 2.0, new solar customers still receive retail credits for most charges on their bill. However, a number of so-called non-bypassable charges are no longer rolled back at full retail rate when solar energy is exported to the grid. These fees fund public projects such as nuclear decommissioning and are typically a small part of your bill. Also under NEM 2.0, new solar customers are required to switch to a Time of Use (TOU) plan (whose rates vary by time of day), except in SDG&E where mandatory TOU requirements are on hold until a later date.

Switch customers can now model customer savings using both California’s NEM 1.0 and NEM 2.0 systems and receive the industry’s most accurate savings forecasts. The difference in savings between the two NEM programs depends on a customer’s electricity usage patterns and the corresponding size and energy production of their solar system.


Note that anyone interconnected before the cap expires will remain on the NEM 1.0 rates for 20 years following their interconnection date.

Aloha State Rate Changes and Export Limits (HECO, MECO, HELCO)

California is not the only state that has historically benefited from NEM but is now experiencing some big changes. In Hawaii, high electricity prices drove one in four single family homes to have rooftop solar. In aggregate all these installations can intermittently export large amounts of energy back to the electricity grid. Citing grid stability concerns, Hawaiian Electric Company ended their  NEM program to all new residential solar customers last year.  Similar to California, existing NEM customers will be grandfathered for 20 years from their interconnection date.

What’s replaced it? New solar customers in Hawaii now have two choices. Option one is called Customer Self Supply (CSS), is very different from NEM, and is truly a first for the solar industry in the US. Any home adopting the CSS tariff cannot export any electricity to the grid. In practice this means the home must also install energy storage or other approved load shedding technology to store excess energy produced by the solar system. To encourage this, homes will receive expedited interconnection.

Option two is Customer Grid Supply (CGS) which is similar to what it’s replacing, in that exported energy does generate credits. However, these credits do not add up to full retail rates, and are only guaranteed for 2 years. There is a very low cap on how many systems can qualify for CGS, the tariff will likely close in late summer of this year.


CGS customers will have dual register metering systems installed as part of interconnection. This will accurately track two values over time; i) the amount imported by the home from the grid, and ii) the amount the home exported to the grid.  

Genability Now Handles Coincident Export & Import

We’ve updated Switch to support changes in Hawaii and California. A critical part of supporting these policy changes is intelligently forecasting how much energy is exported into the grid at any point in time. We’re now able to determine coincident import and export values without having granular consumption and production data.

At any moment in time, a home with rooftop solar could be either importing or exporting from/to the grid. The home will import electricity when all the appliances, HVAC, etc. are consuming more energy than the solar system is generating in that instant. Similarly, the home exports energy when the solar system produces more than the home is using in that instant. Coincident is how much solar production lines up with electricity usage in that instance. Under full retail rate NEM this wasn’t important because a home would get the same rate credit for exports and rate charges for imports. These new tariffs credit exported energy at a new lower rate, so it’s important to accurately forecast the two separately.

With this upgrade, Switch calculates coincidence and determines import and export levels. We take usage and solar production values for each hour in a year, and forecast how this will translate into the amount imported and the amount exported during that hour. Our algorithm takes into account the relative size of the load vs solar production as well as the inherent variability in both. For instance, in late evening when the sun is setting and homeowners are back from work, the algorithm may predict all solar goes toward offsetting usage — i.e., 0 kWh exported — since production is much lower than consumption with little variability. However, for certain hours when consumption and production are similar, as is common in the mornings, the Savings Analysis call will carefully calculate how much usage is imported, how much solar goes to offset usage, and how much solar is exported to the grid.

Despite the complexities introduced by assigning different values to self-consumed vs. exported electricity, Genability Switch still gives accurate savings forecasts. This is made possible by accounting for the fact that household load and solar production may not be equal every minute, even if net export is 0 over the course of an hour.

How Can I Take Advantage of These Upgrades?

For those already using Switch, no additional parameters need to be specified in Savings Analysis calls to model the coincident import/export pricing — you only have to ensure that your call references the correct post-solar tariff (e.g., PG&E’s E-TOU-A or E-TOU-B). These calculations support the usual monthly consumption values by taking advantage of our Intelligent Baselining feature.  Genability will continue to track policy changes in California and elsewhere to ensure that Switch calculates savings accurately and always per released tariffs.

Creating Savings Analyses under California’s NEM 2.0 and grid export systems in Hawaii are just a few of the powerful new additions in Switch V4. You can learn all about Switch here.

For those not using Genability’s Switch API, we’re happy to show how this and other Switch v4 upgrades can help your team. Email us at to set up a demo of Switch.

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Genability Switch V4: New APIs

Over the past few weeks we’ve introduced Switch API upgrades including Dash, a web-app to view and troubleshoot savings analyses, and Savings Analysis Watch, which automatically reviews Savings Analysis results for atypical results.

To complement these new features, you can now access information on historical savings analyses through the Savings Analysis History API, and on the results of the real-time data quality checks via the Savings Analysis Watch API.  This allows you to integrate all the functionality of Dash and Watch directly into your quote tool.

Savings Analysis History

The Savings Analysis History endpoint allows users to view historical savings analysis requests and results. Altogether, this provides an API through which you can see the evolution of a proposal for a potential customer.

Specifically, the Savings Analysis History endpoint lets you obtain historical calls for a particular account using one of the following requests:

GET /rest/v1/accounts/{accountId}/analyses
GET /rest/v1/accounts/pid/{providerAccountId}/analyses

Either of these requests will provide information on all Savings Analysis calls made for this account. You can also retrieve a particular Savings Analysis for an account:

GET /rest/v1/accounts/{accountId}/analyses/{savingsAnalysisId}
GET /rest/v1/accounts/pid/{providerAccountId}/analyses/{savingsAnalysisId}

These requests will return the unique identifier of the Savings Analysis call, the created date, and the summary information originally returned (e.g., preTotalCost, lifetimeSolarCost).

Savings Analysis Watch

Detailed in a recent blog post, Savings Analysis Watch is a tool that monitors the quality of Savings Analysis calls in real-time. While Dash offers a web-interface to view the Watch results, you can also query for the results via the Watch API for a single savings analysis call, or for multiple calls.

To view all Watch results for a particular savings analysis, use one of the following requests:


The requests will return the definition of the data quality check and the status of the Watch result (e.g., “Passed”).

The request to view Watch results for a set of savings analyses uses the following syntax:

GET /rest/v1/watch/results/{filters}

Where you can filter by utility, when the original Savings Analysis call was made, and status of the Watch result.

Using the New APIs

More information on how to integrate with the APIs is found in our Genability Developer Documentation on Savings Analysis History and Savings Analysis Watch. You can also contact with questions.

Those who aren’t currently Switch customers but are interested in leveraging these APIs and the other Switch V4 features, set up a demo by emailing today!

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Savings Analysis Watch: Monitoring the Quality of Your Proposals in Real-Time

Around 60,000 proposals for rooftop solar are expected to be generated per week in 2016. In the competitive landscape of distributed energy generation and storage, how can companies reasonably monitor the integrity of these proposals?

Genability is pleased to announce Savings Analysis Watch ─ a tool that assesses the quality of solar quotes in real time. This allows you to stay informed about the quality of proposals by monitoring up-to-the-minute Watch results, ultimately helping to reduce potential errors as they occur, and improving the overall experience at the point of sale.

How does it work?

When a Savings Analysis call is made, Watch compares the calculated Avoided Cost to an expected range in real time. A status is assigned to every comparison that is run: passed, failed, or failed critical. These denote whether the Avoided Cost is within the expected range, outside of the range, or significantly outside of the range.

For example, you use Genability’s Switch API to create a solar proposal for the home at 123 Genability Drive, San Francisco, CA, 94109. The Savings Analysis call made for this scenario returns a predicted Avoided Cost of 11.0 ¢/kWh. Simultaneously, Watch compares the calculated Avoided Cost to a range typically seen for addresses served by the utility in that area.

switch_v4_dt_01-01Similar addresses in PG&E’s Baseline Region T, typically exhibit Avoided Costs between 13.1 and 34.3 ¢/kWh. Watch then calculates the severity of failure (non-critical versus critical) based on how far from the expected range the check falls. Although this Avoided Cost has been flagged, it does not necessarily indicate there is an error (oversizing a PV system may legitimately lead to low Avoided cost, for example). Rather, the failed check suggests that Avoided Cost is atypical enough that someone may want to take a second look.

Where do the expected ranges come from?

To determine expected ranges, Genability examined the Avoided Costs calculated for nearly 2 million Savings Analysis calls.

Currently, we have about 120 checks covering areas (PG&E Baseline Region T for example) served by the top 50 utilities, where the expected ranges are based on statistical analysis of tens of thousands of savings analyses. We also have 48 state-level checks, which have relatively wider expected ranges. These particular ranges were based on analysis of historical Savings Analysis calls along with Avoided Costs generated using our national set of typical load profiles.

As the trends in Avoided Cost evolve over time (largely due to changing tariff rates), we will continue to update the expected range values, as well as expand coverage to other utilities.

How do I see Watch results?

There are three ways to see Watch results:


Genability’s new web app Dash, provides a simple UI to review and manage a list of Watch results, as seen in the image below. You can filter or sort by date, status, state and utility. Clicking any check result takes you to a view with information on the original Savings Analysis request and result. This can quickly help identify what may be triggering a check result — minimum bill charges being invoked, leading to a low Avoided Cost, for example. (The basics of viewing a specific account or Savings Analysis in Dash was covered in a previous blog post.)


Real-time email notifications

Watch can optionally send email notifications in real time. These emails are only triggered when Watch indicates a Savings Analysis leads to a critical-level failure. An example of what this email alert looks like is below. The email is sent immediately after the Savings Analysis is run.

Email alerts are inactive by default, but can be configured upon request. There is flexibility to customize which utility Avoided Costs you want to be notified about and which you’d rather not receive alerts for.

Savings Analysis Watch API

Finally, Watch results can also be accessed and integrated into your platform via a new API endpoint. This will be covered in an upcoming blog post.

I need to use Watch! How do I get started?

All Switch customers can access Dash and the Watch API. Email for questions on accessing these resources or if you’d like to start receiving real-time Watch notifications via email.

Those without a subscription to Genability’s Savings Analysis API can email to get a demo of our Switch product!


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Genability Switch V4: Introducing Dash

Dash is a visual tool we developed to complement your origination platform and help guarantee that you are generating high quality proposals. This self service web-app takes the power of the Switch APIs and makes them easily accessible to quickly view and troubleshoot savings analyses, review and change account settings, and perform scenario analyses.  

The video includes a sneak peak at Watch, a real-time data quality check of savings analysis call parameters.  Watch monitors savings analysis calls and raises a flag when these parameters fall outside of expected ranges. In our next post we will be following up with more information about Watch.

If you are a Switch customer and have questions about Dash, or would like a site specific demo, please contact support at

If you are interested in Switch and want to learn more email us at

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Genability Switch V4: Accuracy Upgrades

Genability Switch makes it easy to accurately forecast savings and avoided cost, even in markets with increasing regulatory and tariff complexity. With Switch V4, we’ve implemented multiple upgrades to ensure your proposals always reflect accurate solar savings.

Solar Tariff Eligibility

When a post-solar tariff is not specified in Switch, Genability now defaults customers to the most popular tariff eligible for solar customers. If you select a post-solar tariff that the customer is not eligible for, the API response returns a warning. A few utilities now require customers to migrate to certain tariffs once they’ve installed rooftop solar. The first example of such a policy is in Salt River Project, which mandates that residential customers must switch to tariff E-27 after installing solar.

Tracking Closed Tariffs

Genability Switch maintains rate information for all tariffs, including those that are closed and no longer open for new enrollment. With this Switch upgrade, you can quickly sort tariffs by availability to ensure that your sales team only suggests switching to tariffs that are open for new enrollment.

Solar + Energy Efficiency

Many customers bundle energy efficiency upgrades into their solar service offering. Now you can run a Savings Analysis and explicitly pass through load profiles related to energy efficiency products, as well as baseline and solar profiles.  

Support for Complex Minimum Bills

When residential solar systems are sized to offset nearly all of a home’s load, customers are still billed per their tariff’s minimum charge. Recent tariff changes have added complexity to how minimum charges are calculated. For example PG&E recently modified the calculation behind their minimum charge. Switch accurately represents how these minimum charges are calculated to ensure accurate savings for customers with larger systems.

How Do I Leverage These Upgrades in My API Calls?

Some of these upgrades are enabled by minor changes to existing API calls. Contact if you have any questions and we’ll send over implementation details and schedule a demo.

Within the next few weeks we’re dedicating an extensive blog post to upcoming Switch upgrades that greatly enhance support for NEM 2.0, HI, and other tariffs based on bidirectional meters.

Stay tuned for more information on that and other exciting upgrades!

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Genability Switch V4: Dash, Watch, New APIs and More!

We are proud to announce a series of exciting new upgrades to our flagship product, Switch. Switch is the market leading solution for providing residential solar customers with the most accurate savings forecasts.  

Multiple new features are included in this launch, all aimed at increasing accuracy, productivity, and providing you with visual tools that compliment your solar sales process. Over the next few weeks we’ll be following up with a series of blog posts, instructional videos, and other content to highlight significant features.

Dash: View and Troubleshoot Savings Analyses

Dash: View and Troubleshoot Savings Analyses

Included in this release are:

Dash – a new web-app which allows you to quickly view and troubleshoot savings analyses.  

Watch – real time data quality checks which alert users when key parameters in a savings analysis exceed expected boundaries. Watch alerts are available via API, email, and viewable in Dash.

New APIs – several new APIs that can be integrated directly into quote tools. These APIs include all information available in Watch and Dash along with access to historical saving analyses so that you can review historical proposals and see the details associated with any offer.

Accuracy Upgrades – We’re rounding out Switch v4 with accuracy improvements that facilitate changes in regulatory policy related to tariff eligibility, net metering credits, and minimum bills.  

Stay tuned for more updates about all of the new features in Switch.  In the meantime if you have any questions, please  check out the What’s New page on our website or contact us at

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It’s the Middle Class Driving Solar Growth

_I1C8028-2_sharpSeven Solar Installations in a Northern California Neighborhood, March 29, 2016. Photo by Charity Vargas

Who’s going solar? A recent study by Kevala Income Distribution of Rooftop Solar covering 2008-2015 points to California’s middle class.  As solar costs have decreased and competitive new financing options have increased, more and more middle class homeowners are adding solar to their roofs. As many as 65% of California’s solar systems were installed in zip codes where the median owner-occupied income is less than $70,000 per year. Discussing the study with Solar Industry, Bernadette Del Chiaro, executive director of the California Solar Energy Industries Association, suggests that “middle-class consumers are seeking to generate their own power as part of a tangible solution to rising electricity costs.”

The Kevala study also found that moderate-income neighborhoods in Los Angeles County (between $40,000– $70,000) have seen “very strong growth” up 30% year over year. And in Fresno, zip codes with homeowner-median-income of $40,000- $55,000 consistently represented half the solar deployment. What is driving this eight year trend?  Savings. The study concluded that  “10-20% savings in their electricity costs is meaningful enough to drive investment in alternative electricity supplies.”
How much can your customers save? With Genability Switch solar companies can calculate and present their customers savings, helping them install solar where it makes sense – increasingly for moderate and middle income homes.

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Genability Closes a $3 Million Investment

Today we are pleased to announce we have closed a $3 million investment from WindSail Capital. WindSail helps companies that advance energy innovation, with a particular focus on energy sustainability ( They provide debt to companies with solid financials and strong revenue growth. They really couldn’t be a better fit and we are very excited to partner with them.

Continue our Independent Growth in Solar

This investment allows us to continue to support the growth of distributed solar. We have doubled our revenue every year (US solar should grow 119% next year according to GTM) and along the way acquired the best in the industry as our customers and partners. We plan to continue this trend through further adoption and utilization of our existing products (like Switch which is integral to 45% of all solar PV proposals in the US) and by bringing innovative enhancements to the market. But just as important, this allows us to stay an independent and trusted source for savings.

Solutions for the Expanding New Energy Economy

We are at a crucial and exciting time for the new energy economy. More pieces are maturing towards mass market, such as behind the meter storage, electric vehicles and connected buildings. We expect these areas to provide additional growth for us over the next three years, and we will be focusing on upgrades to Conduct, our real time product, and our partnerships with emerging leaders.

New Products, New Reach

We also have several new, exciting products in development that expand our customer base. These include some powerful tools to visualize energy costs and savings across markets, utilities, new energy products and more; to intelligently understand trends and unlock opportunities. We will also expand our reach to target new stakeholders, including traditional utilities. We can’t wait to share more about our new products over the summer.

Financial Strength During Choppy Waters

The transition to a new energy economy will not come without its challenges. While growth is high, its path and timing are not as clear as other technology areas. Consumer adoption, regulatory change, and emerging financing alternatives will all require adjustments to business models and priorities. There will be winners and losers as this shakes out. And as many in our industry know, cleantech and energy technology venture capital has been challenging over the last few years. Add to that the recent tightening across the broader VC funding market, and many emerging software companies not yet profitable could find themselves running out of runway. Today, Genability is in a strong financial position to thrive in this climate.

Welcome WindSail

Mike, Ian and the WindSail team join a great team of investors, who have collectively invested over $10.5 million. Genability remains employee focused, with founders and employees owning 77% of Genability. That being said, our existing investors remain an important part of the team, especially EnerNOC, whose CEO, Tim Healy, will continue on the Company’s board of directors. A big thanks to Tim, Micah and the entire EnerNOC team for their decisive help in this transaction and continued support more generally.

Next up? We’re enjoying a glass of champagne here then getting back to work!

Here’s our Press Release:

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Investigating the Effect of California’s NEM 2.0 on Solar Savings

In January, the California Public Utilities Commission (CPUC) approved new net metering rules, which define how utility companies bill customers with rooftop solar. Largely hailed as a victory for advocates of the distributed solar industry, the NEM 2.0 policies change how the utilities calculate costs and credits for solar customers.

Through 3,000 simulations, Genability investigated how these new rules will impact solar savings. Note that these simulations are based on the NEM 2.0 versions of the utilities’ residential tariffs as of February 2016; updated analyses will be provided soon based on recent changes to the relevant tariff schedules.

From these simulations, we found that NEM 2.0 can have a relatively small effect on savings on average. And more interestingly, NEM 2.0 may lead to greater savings in certain cases.

NEM 2.0 rules

Once the NEM 1.0 rules expire in 2016 and early 2017, potential solar customers served by Pacific Gas and Electric (PG&E), Southern California Edison (SCE), and San Diego Gas and Electric (SDG&E) will have their solar savings impacted in two major ways1,2:

  • All electricity delivered by the utility company is subject to higher charges (“non-bypassable charges”; e.g., nuclear decommissioning charge); these charges cannot be offset by solar energy credits.
  • Customers must switch to a time-of-use (TOU) rate schedule in which the cost of electricity delivered by the utility company varies over the day.

Per the CPUC’s January ruling, both of these factors are resolved hourly, meaning the utility calculates charges from hour-to-hour. Note that SDG&E customers will not need to switch to a TOU rate structure until a later date (several months after the onset of NEM 2.0).

The analysis below focuses on the rules approved in January’s CPUC decision and February tariff schedules. We will publish follow-up analyses as needed with new electricity tariffs including those still requiring approval by the CPUC.

How will NEM 2.0 affect solar savings?

Using Genability’s Savings Analysis product (our Switch API), we ran 3,000 simulations to compare savings for new solar customers under NEM 1.0 and NEM 2.0 rules. These simulations reflect randomly-selected combinations of monthly usage and solar production levels that are typical of cases run through our Switch API. These scenarios generally feature total annual consumption between 9,000 and 17,000 kWh, and solar installations that offset between 60% and 100% of this annual consumption. A more detailed explanation of our simulation procedure is included at the end of this post.

Ultimately, we found that NEM 2.0 has a relatively modest effect compared to NEM 1.0: over all the simulated savings analyses, there was only a 2.8% difference on average in first year solar savings ━ and this was a 2.8% increase in savings.

The chart below breaks down these annual costs by utility. Specifically, it illustrates utility costs for a year without solar, with solar under NEM 1.0 conditions, and with solar under NEM 2.0 conditions. (These values are averages across the simulations by utility.)

Similarly, the bar graph below shows the average amount of savings in utility costs per year thanks to solar (i.e., what you avoided paying the utility).

Both the chart and bar graph highlight the relatively comparable savings seen under each of the NEM conditions. That said, PG&E and SCE customers can actually benefit from the NEM rule changes: nearly 95% of the simulated PG&E customers and more than 95% of the simulated SCE customers saw higher savings under NEM 2.0 versus NEM 1.0. More specifically, annual savings increased by 5.7% ($146.20 in the first year) on average for the PG&E scenarios and 5.3% ($149.80) on average for the SCE scenarios.

SDG&E customer simulations saw lower solar savings under NEM 2.0 versus NEM 1.0. That said, the effect was small ━ only a 2.5% decrease on average ($85.27 in the first year). Even in the most extreme SDG&E case, there was only a 4.0% decrease in savings due to NEM 2.0.

We also assessed the effect of the new rules by examining the rate a customer pays to the utility for power after having gone solar (i.e., yearly amount paid to the utility divided by the total kWh delivered by the utility). The plots below depict the distribution of these post-solar rates:

As expected, the plots indicate that solar customers would pay higher rates to SDG&E under NEM 2.0 versus NEM 1.0 conditions, while the reverse is true for PG&E and SCE.

Altogether, these relative patterns of savings indicate that the positive effect of the TOU switching rule in NEM 2.0 (delayed for SDG&E) outweighs the negative effect of the higher non-bypassable charges.

Integrating NEM 2.0 rates into Savings Analysis calls

Overall, the non-bypassable charges appear to impact solar savings only slightly. In the PG&E and SCE NEM 2.0 scenarios, the switch to a TOU rate generally has a much larger, and often positive, effect on savings3.

As of last week, Genability’s Savings Analysis API can predict savings based on California’s new net metering rules. For more information on how to do this, or for analysis of how your organization’s specific quotes will be affected, email

Those without a subscription to Genability’s Savings Analysis API can email to get a demo of our Switch product.


How we ran this analysis

We determined 500 usage and production scenarios that are representative of potential rooftop solar customers served by each of the three California IOU utilities.

As a single hypothetical example: we used Genability’s APIs to create an account for a customer, John Smith, at 123 Genability Drive, San Francisco, California, 94114. We then created annual usage and solar profiles and uploaded them to the John Smith account.

For the John Smith scenario, we then ran a Savings Analysis call where the pre- and post-solar tariffs were the same ━ both PG&E’s E-1: Residential rate schedule; in other words, pre_master_tariff_id = post_master_tariff_id = 522 in the API call, where 522 denotes PG&E’s default residential tariff in Genability’s database. The results of this Savings Analysis call represent the NEM 1.0 case.

Next, we ran a nearly identical call, but set the post-solar tariff to the NEM 2.0 version of E-6-TOU: Residential – Time of Use. For this, we also set useIntelligentBaselining = true in the API call, which interpolates hourly usage data from a single monthly kWh reading (as described in a previous blog post). Altogether, this second Savings Analysis call predicts costs and solar savings under California’s new NEM 2.0 rules. We then compared savings under the NEM 1.0 and 2.0 conditions.


1 A one-time interconnection fee is also now allowed, but this is not part of the electricity tariff.

2 The invester-owned California utilities (PG&E, SCE, and SDG&E) have recently asked that charges be resolved at a sub-hourly level. The CPUC is expected to respond in the coming months.

3 Particularly for cases where the solar customer’s annual utility charges were above the annual minimums.


Read More »

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