January 15, 2019 0

Welcome to the new SepiSolar website. Here’s how we listened to you. 

If you’ve ever been to SepiSolar.com for design and engineering services, you’ve probably just noticed that our website has changed–a lot.

Why did we redesign our website? Because we listened to you, our customers and potential customers, who wanted a better user experience. With that in mind, here’s a brief tour of the new SepiSolar website with some highlights of what’s changed.

Better Navigation

We’ve heard from you that extra clicks mean extra time finding the exact design and engineering services that you want. To improve navigation and user experience, we made all of our core services visible on the home page. With one click, you can now learn more about, say, our commercial design services,  or energy storage. The home page also has direct links to information about or our various technical consulting services, administrative services, and SepiAcademy, our new online training platform.

Still can’t find what you’re looking for? Use our search windows at the very top and in the blue footer of the website.

More Resources

SepiSolar website visitors often never knew they could download sample designs, site survey checklists, and more. To make these assets more visible, we now have “Resources” on our main navigation bar. There you’ll discover that we’ve added utility and microgrid design examples, as well as find pages for SepiSolar case studies, white papers and finished project photographs.

More Personal

As you’ll see in our About page, SepiSolar’s mission is “to build a community of designers who care about solving tomorrow’s energy problems today.” We take that mission seriously, so the new website reflects that in several ways. First, we put a face to the designers and engineers and staff that you often speak to.  You can also read some of our engineer’s thoughts on the home page, as well as get to know them a little better via our team page, another new section of the site.

You’ll also see quotes from our customers and why they use SepiSolar for their design and engineering services. Blogs will also be more personal and written by specific team members, not a nameless admin.

Finally, you might also notice a new FAQ button on our website. These are all general questions that we often here, but you’re always welcome to contact us directly for your personal question. If you’re new to SepiSolar and need a quote for design or technical consulting, well, there’s a big orange button in the top right of every page. There you can register for our SepiPortal and get a fast estimate for one or several designs. Already registered? Log in, as usual, using the red SepiPortal button at the top right of every page.

That’s the new SepiSolar.com new website tour. If you find a broken link or have other improvement suggestions, please let us know at blogs@sepisolar.com (also new!)

It’s always a team effort here at SepiSolar, but I have to give a special shout-out to Lean Digital Systems, our web designers. If you love this website, we’re confident they’ll create a beautiful, personal, and user-friendly solar website for your solar or energy storage company too!


July 7, 2018 1


We’re delighted to share the news that SepiSolar’s CEO, Josh Weiner, has been named to Renewable Energy World’s inaugural “Solar 40 under 40” list.

What does it mean to be on the list?

According to Renewable Energy World’s editors, “Solar 40 Under 40 recognizes these individuals and their unparalleled accomplishments within the solar industry. Their mission is to bring solar far into the 21st century and build on the roots of the solar industry and those who have come before them. They are, and will continue to be, advocates for solar. Each one is unique, shows a great deal of passion and has achieved accomplishments within the industry.”

We recently posted a blog about Josh’s solar origin story. It began with Akeena Solar in 2004 and eventually led to founding SepiSolar in 2009.

While growing SepiSolar into a national solar + storage design, engineering and consulting firm with over 6.5 GW of residential, commercial, and utility designs, Josh co-founded Green Charge Networks, managed NRG Home’s engineering department, and has consulted with many solar asset owners and manufacturers on developing and commercializing cost-effective energy storage.

With SepiSolar’s membership in CALSSA, Josh has also been instrumental in developing solar+storage policies that are a win-win-win for utilities, contractors, and solar customers. Josh is also dedicated to educating the next generation of solar PV designers, and has taught advanced solar design courses at UC Berkeley.

If you’ll be attending Intersolar, you can meet Josh in person at Renewable Energy World’s honoree ceremony, Tuesday, July 10, at 3:30 pm on the ees Stage on Level 2; at the Intersolar Tweetup; as well as at our Intersolar edition of Ask SepiSolar Anything.

Congratulations, Josh!


June 20, 2018 0

If you missed our first Ask SepiSolar Anything with SepiSolar’s CEO Josh Weiner answering solar+energy storage questions, you can’t ask any more questions, but you can listen to the whole session here:

Josh tackled some great questions from people tuning in to this live and interactive program:

  1. What are some of the common KW inverter sizes for C&I solar+storage? (at 11:12)
  2. When you’re doing solar PV plus storage, what kind of interconnection requirements, like 120 percent rule, do people face? Are you seeing more AC or DC coupling on the system? (at 13:20).
  3. For commercial solar+storage, who are the customers that would benefit the most from solar+storage, and who are the customers that aren’t yet ready? (at 20:40)
  4. What type of energy storage is available and viable for the Florida residential and commercial market? Which brands? Also, does storage benefit from the 30% ITC credit if installed in conjunction with solar? (at 26:00)
  5. For O&M requirements for lithium-ion batteries for C&I solar+storage applications, is there maintenance required on a yearly basis? Or is it bi-yearly? What kind of components need to be serviced? What kind need to be replaced? (at 30:15)
  6. Is there an unbiased accurate chart from an independent testing lab of expected life cycles of all that all the battery brands? (Short answer, yes, but there’s only one that’s public.) (at 38:02)
  7. How does energy solar PV and energy storage work with virtual net metering and aggregate net metering? (at 43:22)
  8. What is the unit based cost for battery O&M? (at 47:10)

Join us for our next Ask SepiSolar Anything

If you have more questions about solar+storage, or energy storage or anything related to solar, join us for our July edition of Ask SepiSolar Anything. You can be in the audience and ask your questions live at Intersolar North America or tune in virtually.

Topic: Ask SepiSolar Anything about energy storage technologies. Josh will be answering questions with our special guest, Matt Harper, Chief Product Officer of Avalon Battery.

When: Thursday, July 12, at 1pm Pacific.

Where: Sign up to get a link to watch via the web or join us live at Intersolar. Get all the info and a reminder here!

P.S. If you’re on Twitter and want to meet other solar people behind the solar brands on Twitter, RSVP for the 8th Annual Intersolar Tweetup, which @SepiSolar is sponsoring. Space is limited.


May 30, 2018 0


If you’re an architect, new homebuilder or housing developer in California, you’ve probably heard by now that the California Energy Commission (CEC) has updated its Title 24 solar and energy efficiency standards. Effective January 1, 2020, the update specifically mandates that all new California homes under three stories install solar panels on the roof or achieve an equivalent total home energy efficiency reduction through other measures.

To comply with Title 24, new homebuilders, architects and developers will be required to use Title 24’ssoftware for calculating the building’s “Energy Design Rating” (EDR), which not only includes inputs for solar but also for energy storage and other options.

To give builders more flexibility, the EDR is scored like a golf tournament—the lower the score, the better (or, the more “energy efficient” the home is). The goal is to achieve an equal-to-or-less-than EDR for a solar home than a comparable “regular” home, of the same square footage.

Depending on the square footage and climate, new-home solar will range between 2.7 and 5.7 kW DC to meet the requirements, but that doesn’t tell the whole story. Rather than meeting the minimum requirements, builders may be better off designing their Title 24 solar systems with battery storage.


Why Builders Should Include Storage with Solar

As mentioned, the EDR software gives homebuilders a score, but there are many ways to meet that score, and one is combining solar with energy storage. Including energy storage will not only meet the minimum solar requirements, but will maximize energy savings for the home, offering customers a financial advantage over other homes.

When solar engineers design a solar system, they typically take into consideration the following factors:

  • The climate
  • The average amount of sunlight for the area
  • The orientation of the roof in relation to the sun
  • The amount of potential shading over the course of the year
  • The pitch of the roof
  • The home’s annual kWh usage

While these parameters are important, equally important are the utility rate considerations that system designers like SepiSolar factor into their plan sets. These rate policies affect the solar system’s ROI and include:

  •  Tiered Rates. Tiered rates vary by utility and charge customers higher rates when they use more energy over a certain monthly amount.
  • Net Energy Metering (NEM). NEM is like rollover minutes for solar. Utilities will credit solar homeowners for any excess solar power that is exported to the grid. The value of NEM varies by the utility and the time of day that the solar is exported to the grid.
  • Time of Use (TOU). TOU rates also vary by utility. Customers incur charges when they use grid energy. During peak times, such as rush hour when the sun is setting and people are coming home, utilities charge solar and nonsolar homeowners a higher rate when they draw power from the grid, making any exported solar energy less valuable during that time of day.

That’s where energy storage (batteries) comes in.


Designing Systems for Overall Cost Savings for Solar and Title 24

Due to the above utility rate considerations, home developers that want to design premium homes that maximize utility savings as well as comply with the Title 24 solar mandate should consider including energy storage systems with their solar designs.

Solar+storage with smart battery management software will counteract the cost of tiered rates and TOU through “load shifting,” and “peak shaving.”

With peak shaving, homes using solar+storage will be able to use as much free solar as they can during the highest TOU rates while saving the excess energy in their batteries instead of exporting to the grid. Then, during peak TOU periods, the home will use this free stored solar-generated energy when the utility rates are high.

Additionally, battery management systems can also “load shift” the time when appliances are turned on or off, such as turning on a dishwasher, dryer or charging an EV when utility rates are low or when electricity can be drawn from the battery that was charged by solar.

Both peak shaving and load shifting with solar+storage encourage the home to use more of its own self-generated power, relying less on importing power from the grid. With so many homes using solar after 2020, homeowners with solar+storage will also help stabilize the grid, and can be paid a higher credit for any power the utility draws from the storage system during peak hours.

Another sales advantage for developers is that solar+storage offers some emergency power in case of a blackout. That is not the case with stand-alone solar PV systems. To protect power line repair workers, stand-alone solar systems will automatically shut down during an outage.


Things to Keep in Mind About Solar+Storage with Title 24

If you decide to meet your Title 24 solar mandate with energy storage, there are several requirements to keep in mind.

First, when adding storage to solar, there is a minimum required battery size of 5 kWh. This is a reasonable size that will allow for taking advantage of tiered rates and TOU, and it will provide a minimal amount of backup power in case of an outage.

Second, your solar+storage system designer and engineer will have to select one of three control options for the battery:

  • Option 1 – Basic Control (Title 24, Section JA12.2.3.1): With Basic Control, the battery system can only be charged by the solar system and can only discharge when there’s not enough solar power to meet the home’s current energy usage.
  • Option 2 – TOU Control (Title 24, Section JA12.2.3.2): With TOU Control, battery system will be set up with Basic Control, but will only discharge during the peak TOU hours of the day. This will change from season to season, and must be configured from the battery manufacturer or programmed by the installer at the time of commissioning.
  • Option 3 – Advanced Demand Response Control (Title 24, Section JA12.2.3.3): With this configuration, solar+storage systems will be programmed with Option One or Two. In addition, the battery control system must meet the demand-response requirement of a utility or third-party owner; that is, the utility or third party will be able to remotely control when the battery is charged and discharged. Typically, the homeowner will receive a financial benefit for this utility interaction with the grid.

The rules within each category will most likely be refined over time, so it’s important for your solar designer to be up to date with these standards and make any necessary changes. The above is a summary, so please review the entire Joint Appendix 12 to take full advantage of the above credits.

As longtime solar+storage engineers with thousands of projects, SepiSolar has a great deal of experience designing solar and battery systems that meet the new Title 24 regulations, as well as designing systems that comply with the local requirements of counties and other local authorities having jurisdiction (AHJs). Please contact us if you have any questions about these new Title 24 solar requirements for your new residential solar development projects.

Josh Weiner is President and CEO of SepiSolar, a solar+storage design & engineering firm based in Fremont, CA.


May 4, 2018 1

Have you seen SepiSolar’s new logo? It used to look like this:

And now it looks like this:


When any company goes through a redesign of their brand, customers and frequent visitors can notice and often have an initial reaction (they love it, they hate it, meh.) as well as questions, like “What was wrong with your old logo?” and “What does your new logo mean?” and “What does the number 42 and meaning of life have to do with solar design and engineering?

These are all great questions, so let’s tackle them one by one:

What was wrong with your old logo?

Sometimes our solar engineers can be checking a permit plan set and spot something on the plans that doesn’t match or make sense. That’s how we felt about our old logo. The solar panel array made us look like a solar developer or EPC, and while solar contractors are certainly our customers, a solar array is not a reflection of design or engineering or who we are beyond being in the solar business.

Second, when you look at a brand, it’s supposed to reflect a feeling. Think about Nike and that swoosh of energy. We want the solar industry to recognize SepiSolar in that same way, to see our logo and have a positive feeling, and our old logo never did that. It was “just a logo.”

What does your new SepiSolar logo mean?

Designing and engineering a logo is serious business, and we did consult with a professional who asked us a lot of questions about who we are and what does our SepiSolar name mean?. The short answer is that “Sepi” means “the moment just before the first light of dawn.” So, light and energy emerge and grow from Sepi, and in the same way, solar projects and the power that is later generated emerges out of the plan sets that SepiSolar’s engineers create. Power also emerges out of the engineering solutions we solve as solar consultants.

Our logo designer created several options to have our new logo reflect who we are as a company, but this was the one that immediately resonated with us. Here’s why: 


“42 and The Meaning of Life”

As to why we put 42 in the title of this post, if you didn’t catch it immediately, the number 42 is an important but ridiculous part of Douglas Adams’ book “Hitchhiker’s Guide to the Galaxy.”

It’s relevant to our SepiSolar brand because we sometimes feel like we’re part of that ridiculous universe when we deal with the bureaucracy of solar and battery permitting requirements, but it’s not part of our logo. We just thought it would be fun to slip 42 into a blog post title, and fun is part of our community of solar “enginerds,” so 42 is relevant…sort of.

Thanks for reading, and if you’ve missed our latest SepiSolar news and useful info like our SepiSolar Battery Translator Tool, please sign up for our newsletter or check out other news and blog posts! Naturally, please contact us if you’d like a free quote for our engineering services.

Josh Weiner is President and CEO of SepiSolar


March 5, 2018 0

SepiSolar’s Josh Weiner was recently interviewed about trends in solar+storage design and engineering by Barry Cinnamon on “The Energy Show,” a radio program on KDOW Radio AM in San Jose California, as well as a popular solar industry podcast.

Josh and Barry have a long solar and storage relationship together going back to when Josh was leading Barry’s engineering department at Akeena Solar, the first national solar installation company. Their lively conversation talks about solar and storage trends, which includes a conversation about some new and improved alternatives to Lithium Ion-based storage systems.

Click below to listen to the show on SoundCloud, or you can also download it as a podcast on Itunes here.


February 28, 2018 0


My fellow solar designers and engineers, make no mistake: We have been and will continue to be an important part of the world’s transition from fossil-fuel-based energy to a world that will be powered by interconnected and networked solar, wind, storage and integrated micro-grids. For those of you who don’t know what you’re getting into, welcome to the renewable revolution and hold on; it’ll be a bumpy ride! For those of you who already know the solar coaster, congratulations and thanks for your contributions! But … our contributions are far from over.

Energy analysts say that our full transition is inevitable, and that clean energy destiny can be accelerated by innovation, efficiency and improved designs, or just as easily decelerated by flawed, fossil-fuel biased or outdated policies, soft costs and careless designs that lead to bad publicity and damaged customers.

My fellow technical subject matter experts, you and I both know that such a transition is impossible without the minds and efforts of professionals like us doing our part. The sort of work we do is based on sound and well-understood scientific principles of math, engineering and technology.

Having studied these materials for quite some time, we know the power they can bring, as well as our responsibility to accelerate them—we are in a unique position to leverage these principles and the tools our industry has developed in order to make them ubiquitous and accessible to all through more streamlined and easy-to-use products and services.

Newton’s first law of physics states: “An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.” Similarly, I would say that the U.S. is transitioning toward 100% renewable energy at the same speed and direction that, while positive in direction, is not moving at a speed that will mitigate the worst effects of climate change, let alone pollution and its health effects.

Consequently, we need an unbalanced force to accelerate that transition, and my fellow solar designers and engineers, that unbalanced force can be you and me. We have the technical ability to accelerate solar + storage adoption and reduce its costs through better and more efficient designs, advocating for better policies, and combining our engineering thoughts. The more we can share best practices, surface the sometimes-nuanced and subtle policy roadblocks that slow our work, and educate policymakers and AHJs throughout the U.S. who are just beginning to see an interest in solar and storage, the faster solar and storage will be deployed and make a difference.

In short, engineers and designers must do our part and lead with our ideas and technical abilities, as well as contribute ideas to changing codes and standards. (Wouldn’t it be nice to one day actually have a truly national solar code?)

It’s for this reason we’re rededicating this SepiSolar blog to sharing solar and storage design and engineering best practices. We also know that this must be a collective effort, so we are opening our blog forum to any solar designer or engineer who also wants to share best practices and thought leadership toward our energy transition.

To contribute your thoughts, please email your posts to blogs@sepisolar.com. As long as it’s useful information (under 1000 words plus any related images, please) that helps to forward thought leadership on design, engineering or permitting for solar, energy storage or the grid, we’d love to publish it here, as well as share it on our social networks and email list. You’ll be fully credited—regardless of which company you happen to work for. From our perspective, solar designers and engineers are not competing against each other, we are competing against fossil fuels, dirty energy, apathy and current policies that stagnate our industry’s growth.

Thank you in advance for contributing, and we look forward to more solar design and engineering leadership.

Josh Weiner is CEO and Founder of SepiSolar

CA Small Business Enterprise

Certification ID:

Bidder/Supplier ID:

NAICS Codes:
541330 – Engineering services
541340 – Drafting services
541490 – Other specialized design services
541618 – Other management consulting services
541690 – Other scientific and technical consulting services
541990 – All other professional, scientific, and technical services

D-U-N-S number:

811024, 81101701, 81101516, 81101604, 43232614, 81101505

Subscribe to the SepiSolar newsletter:

Subscribe Now