09:11:00 am, by Jim Jenal - Founder & CEO   , 421 words  
Categories: All About Solar Power, Solar News

Solar Impulse Soars Across America

If there is anything cooler than a solar-powered airplane that can fly at night, we sure haven’t seen it.  The plane is called Solar Impulse (technically HB-SIA) and it is making its way across the country right now!  In fact, if you live in Phoenix, you could go see it today or Tuesday (and yes, we are jealous) - but the free tickets to see it are all sold out!

Solar Impulse flying over Golden Gate Bridge, San Francisco, California

The plane is making its way across the United States, originating in San Francisco, with scheduled stops in Phoenix, Dallas, St. Louis, DC and New York City.  The information learned during the flight will inform the design and construction of a second plane (HB-SIB) that is intended to fly around the world in 2015.

Here are some specs of the Solar Impulse:

Wingspan: 208′
Weight: 3,500 lbs
Length: 71′
Height: 20′
Motors: 4 (each 10hp)
Solar cells: 11,628

The plane has a take-off speed of 27 mph, an average flying speed of 43 mph and a maximum cruising altitude of 27,900′!

Indeed, the plane has already garnered Five World Records including:

  • Absolute height: 30,300′
  • Altitude gain: 28,690′
  • Duration: 26 hours, 10 minutes, 19 seconds
  • Free distance along a course: 695.5 miles
  • Straight distance over pre-declared waypoints: 683 miles

But how, you may ask, does a solar powered plane fly at night?  Clearly it is not fast enough to chase the sun, so what happens when the sun goes down?  It is all about energy management - both electrical and potential.  During daylight, as the nearly 12,000 solar cells are producing power, the plan climbs toward its service ceiling.  As it goes higher, the solar power system becomes more efficient due to both the drop in temperature and the thinning of the atmosphere.  Thus, the plane is able to store energy in two forms: electro-chemical (in the batteries) and potential in the altitude attained.

When the sunlight fades, the plane begins a very gradual descent, aided by its massive wingspan - equivalent to an Airbus A340 jetliner - that allows it to glide long distances forward for every foot of descent.  Finally it levels off and flies at a very slow cruising speed powered by the solar power now stored in its batteries until it once again meets the sun and can begin its ascent once again.  In theory, the plane could do this perpetually - not so the poor pilot!

Speaking of the pilots, one of them, Bertrand Piccard, has quite the lineage as a pioneer.  His father, Jacques Piccard was aboard the Bathyscaphe Trieste (designed by his father, Auguste) when it descended to the ocean floor in the Mariana Trench - some 35,814′ deep - in 1960!



  10:18:00 am, by Jim Jenal - Founder & CEO   , 452 words  
Categories: Solar News, Non-profit solar

Solar Schools: Great Start, Long Way to Go

Schools with solar installed just make sense on a host of levels.  They save the school money by reducing operating expenses which can then go to teachers and materials to advance the educational mission.  Solar systems are a natural teaching tool,  and they set a great example for the students who are learning life lessons on sustainability. With all that going for them you would think solar power systems would be popping up in schools all over the country - and you would be right, but we’ve got a very long way to go!

The good folks over at The Solar Foundation have started to compile the first ever National Solar Schools Census and it gives an interesting, if preliminary, take on the state of solar schools in this country. Based on the data they have gathered so far, they have identified the following:

Number of Schools in the U.S. with Solar > 637
Total Number of Schools in the U.S. 98,817 (2009-2010)
Percentage of Schools with Solar 0.64%
Total Installed Capacity on Schools 116.3 MW
Combined Annual Energy Savings $20,120,510
Combined Annual CO2 Emissions Avoided 143,394 metric tons

That’s right, as of now less than 1% of the schools in this country have been identified as being “solar schools".  And yet, that tiny sliver of schools is saving over twenty million dollars a year while eliminating more than 140,000 metric tons of greenhouse gas emissions! Beyond a doubt, we have just scratched the surface of this terribly important solar market.

When you visit their site, you find this very cool interactive map:

National Solar Schools Census map

Click to see interactive map

The map allows you to drill down to any local area and see the penetration of solar in the local schools.  The color code is red for systems < 5kW, yellow for systems between 5 and 50 kW, and green for systems > 50kW (like our project at Westridge).  Interestingly, the biggest projects seem to be clustered out West.

The data in the database is largely self-reported - for example, the Westridge project is not yet depicted on that map.  So there are undoubtedly many solar schools out there which have not yet been included in the database.  The Solar Foundation is hoping to cure that by getting folks to send them the information required to get your school listed.  If you are affiliated with a solar school and want to get it counted, please click here to send an email with the following information:

  • School name,
  • School address (including county),
  • System size,
  • How it was financed,
  • Year it was installed, and
  • Whether solar is integrated into curricula.

Here’s hoping that by the next update of the map - scheduled for this summer - we will have twice as many solar schools identified with lots more yet to come.


  08:23:00 am, by Jim Jenal - Founder & CEO   , 246 words  
Categories: Commercial Solar, Energy Storage

Going with the Flow - Batteries, that is!

In our continuing coverage of the ever-growing solar storage industry, we note today a joint project between Stanford University and the Stanford Linear Accelerator Laboratory (SLAC) to develop lithium-polysulfide batteries (h/t RenewableEnergyWorld.com). If successful, the project has the potential to scale readily to provide inexpensive storage solutions for solar systems up to utility size.

In this video, graduate student Wesley Zheng, one of the researchers, demonstrates how a small-scale version of the battery works:

(Interestingly, we noted in our visitor data that we had hits from both Stanford University and SLAC - so maybe they are following us, following them!)

The researchers are working to improve upon redox flow batteries which use rare minerals, like vanadium, and a membrane to support the chemical reaction.  But as the video demonstrates, the new battery is far simpler, requires neither expensive minerals nor membrane, and has already demonstrated significant resiliance to repeated cycling.  Here’s an illustration of the two designs side by side:

Redox flow vs lithium-polysulfide flow battery designs



In our view the race is on to see who can bring a cost-effective solution to market in time to allow solar to overcome the last of the political resistance that it faces from the utilities and their allies.  Cost-effective storage will also trump concerns from potential clients about their actual savings from demand-driven rate structures.

Someone - perhaps this SLAC/Stanford team - will crack this nut and once they do, the world of solar will never be the same.  We are eagerly looking forward to that day.


  09:32:00 am, by Jim Jenal - Founder & CEO   , 367 words  
Categories: Solar Economics, Solar News, GWP, Commercial Solar, Residential Solar, Ranting

SB 43 Advances - Questions Loom for Community Solar Bills

SB 43 - the Community Solar bill authored by Democratic State Senator Lois Wolk - passed its first legislative hurdle yesterday but in doing so it highlighted potential trouble down the road.

The bill passed the Committee on a 6-4 vote but the combination of who voted Nay does not bode well.  Here’s the chart of how they voted:

Senate Energy Committee vote on SB43

First observation - the profile in courage award to Committee Vice Chair Jean Fuller for not voting on the bill at all.

Second observation - two Democrats voted against this bill: Roderick Wright (35th District) and the Chair of the Committee, Alex Padilla (20th District) - what is up with this?

Senator Wright’s district encompasses some decidedly working class neighborhoods in cities such as Compton, Hawthorne, Inglewood, San Pedro, Watts and Wilmington.  We reached Senator Wright this morning in his Sacramento office - he answered his own phone! - and he was very direct in his comments.  He called the measure a “stupid bill” and said he opposed it because of its cost-shifting to other rate payers and that its mandatory purchase and subscription provisions made the bill something he could not support.

We told him about potential clients that we see - like the Glendale woman we met yesterday who so very much wanted to add solar but simply had no viable space to do so - who could really benefit from such a bill.  Interestingly, he cited programs like Glendale’s “Green Energy” rate by which GWP customers could purchase “green energy” by paying a surcharge to GWP.  We say interestingly because presumably the renewable resources that GWP is using to satisfy that requirement have the same potential issues as those provided by a Community Solar provider - for example, the dispatchability of a resource is not dependent upon who owns the resource.

Our conversation touched on a number of subjects - the Senator was very generous with his time - and we came away with the sense that the while he is quite thoughtful on these issues, he will most likely not be an ally in the struggle to preserve net metering as we know it.

Senator Padilla’s office, on the other hand, did not answer when we called.  We will update this post if we hear back from him.


  07:16:00 am, by Jim Jenal - Founder & CEO   , 279 words  
Categories: Utilities, Commercial Solar, Ranting

Dinosaurs - Take Two

There are two competing memes traversing the world of distributed energy generation - the “net metering is unfair” meme (only heard from utilities and their lackeys) and the “utilities are dinosaurs” meme (originally only touted by pro-renewable evangelists like, well, yours truly).

Walmart logo

Far too early to see which meme will win out in the end, but the dinosaurs meme just got a major boost from an unlikely source - Walmart.

Hat tip to our friends over at Climate Crocks for flagging the story about Walmart putting real teeth into its previously stated commitment to generate 100% of its energy from renewable sources.  According to Walmart CEO Mike Duke:

More than ever, we know that our goal to be supplied 100 percent by renewable energy is the right goal and that marrying up renewables with energy efficiency is especially powerful… The math adds up pretty quickly — when we use less energy, that’s less energy we have to buy, and that means less waste and more savings. These new commitments will make us a stronger business, and they’re great for our communities and the environment.

The math adds up pretty quickly for the utilities as well.  Given the size of Walmart’s operations - more than 10,000 stores in more than 20 countries - this is a big deal.  Indeed, Walmart is promising to increases its renewable energy production six-fold over the remainder of this decade - and it already produces enough renewable energy in the U.S. to power 78,000 homes!

No doubt the utilities will decry Walmart’s commitment as “unfair."  But when they do, their bellowing is likely to be heard as the dying sound of the last dinosaur, slipping into the swamp of a business model that has no future.

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Jim Jenal is the Founder & CEO of Run on Sun, Pasadena's premier installer and integrator of top-of-the-line solar power installations.
Run on Sun also offers solar consulting services, working with consumers, utilities, and municipalities to help them make solar power affordable and reliable.

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