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SunPower's new $10K USD solar panel system is specially geared towards offsetting the power requirements of Ford's upcoming 2012 Focus Electric. It offers enough juice for an average driving distance of 32 miles a day.  (Source: SunPower)

SunPower's advanced panel design is more efficient than standard panels, so it takes up less space. The design is the result of 26 years of market experience.  (Source: SunPower)

The 2012 Ford Focus Electric is Ford's first mass produced electric vehicle. A price has not been announced officially yet, but it's rumored to fall around $30K USD.  (Source: Ford Motor Company)
Electric car will essentially be self-sufficient for moderate drivers

Electric vehicles (EVs) are a promising step forward in energy usage, replacing expensive fossil fuel trips with cheap charges (mostly from coal power in the U.S.).  Of course the high cost of lithium and rare earth metals makes the cost equation more of a break-even than a windfall.  Still, the long-term potential to both shirk fossil fuel consumption and its high cost is great as battery costs dip.

I. Ford and SunPower -- a Veteran Team

Some carmakers have been exploring an even more ambitious concept for their EVs -- grid neutrality.  By combining home solar panels, they are able to remove the fossil fuel-based charge from the equation altogether.  Mazda Motor Corp. (TYO:7261toyed with the idea, deploying solar chargers for its small Japanese fleet of converted Mazda 2s. Nissan Motor Co., Ltd. (TYO:7201) took things a step further with its limited international rollout of the LEAF EV, actually offering a rooftop charging system commercially.

Now, Ford Motor Comp. (F) hopes to make an even bigger splash in the world of solar power, offering a special promotion to allow customers to offset their vehicle's power use and attain grid independence.  Ford has partnered with San Jose, California-based SunPower (SPWRASPWRB) to offer solar chargers to buyers of the 2012 Focus Electric, which is set to launch later this year.  SunPower is a company with vast experience in the solar business, having been in operation since 1985.  Ford calls the new program "Drive Green for Life."

We had the chance to catch up with SunPower's North American General Manager, Ken Fong, to learn more about the plans.  He tells us that the SunPower's solution is a completely in-house project.  He states, "SunPower designs, manufactures and delivers the highest efficiency solar cells and solar panels for use in the residential, commercial and utility scale markets."

II. Technical Details Aplenty

The solar chargers for the Focus Electric will use SunPower's proprietary E18 Series silicon based panel design, which is designed to minimized the rooftop space necessary for the charger.

"SunPower’s solar cells are made from multi crystalline polysilicon with an average efficiency of 22.4 percent.  Because of the high-efficiency of the SunPower solar panels, the system takes up less room than a conventional solar array. Each panel is approximately 4’ x 2’, and the total system, which consists of approximately 11 panels, works out to be about 147.3 sq. feet," comments Mr. Fong, "The all-back contact design eliminates the silver lines on the front of the cell, leaving an aesthetically pleasing all-black look to the cell."

Thus the panel system will take up on your roof about the flat space of a 12 ft. by 12 ft. room's floor.

The full system generates 2.5 kilowatts on a sunny day.  It is estimated that in a year it will yield 3,000-kilowatt hours of power, or roughly enough juice to drive your Focus Electric 12,000 miles.  That's roughly an allowance of 32 miles a day -- well within many drivers’ commuting distances.  Of course on cloudy days, you'll get less mileage, as the panels will generate less power, so those with mid-distance commutes may have to occasionally fall back on the traditional charger.

The system is set to retail for $10,000 USD after federal tax credits.  However, customers may be able to get an even lower price based on local and state tax credits.  And customers potentially may be able to sell excess power back to the grid, depending on the policy of your local utility.

Ford has not announced official pricing information on the Focus Electric, but its rumored to be priced at $30K USD, after $7,500 USD federal tax credit.

SunPower also says that customers will have the option to buy two connected systems for heavier driving, if they have the roof space (e.g. 2 systems would give you roughly 65 miles a day of drive distance).

III. Big Plans

SunPower says the system is exclusively targeted towards residential users.  However, they say they're also deploying EV charging solutions to businesses.  States Mr. Fong, "SunPower has many commercial customers who are already enjoying the benefits of a 'car port' solar system."

Mr. Fong is thrilled about the new partnership with Ford.  He states, "Ford is a great partner and we are in sync with our goals to offer customers a clean, renewable way to get from here to there."

The folks at SunPower aren't short on ambition.  Despite the Focus Electric launching in 19 separate U.S. markets at volume, SunPower says it should be able to keep up with everyone who wants one of the chargers.  States Mr. Fong, "SunPower will be able to deliver a solar system to all interested customers." 

In addition to the new solar power system, Ford is using a solar installation to power lighting at the plant that builds the Focus Electric, and is offering early purchasers free (traditional) fast-charging stations in a partnership with Coulomb Technologies, Inc.

Editors Note: DailyTech would like to thank SunPower's Ken Fong for taking time to share these details with us and Emily Rosen for arranging this interview.

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Only in the desert Southwest
By Solandri on 8/12/2011 2:54:07 PM , Rating: 2
"SunPower’s solar cells are made from multi crystalline polysilicon with an average efficiency of 22.4 percent. [...] the total system [...] works out to be about 147.3 sq. feet," [...]

The full system generates 2.5 kilowatts on a sunny day. It is estimated that in a year it will yield 3,000-kilowatt hours of power, or roughly enough juice to drive your Focus Electric 12,000 miles. That's roughly an allowance of 32 miles a day

Once again, marketers are trying to spin best-case scenarios as typical.

147.3 sq ft = 13.7 sq meters.
3000 kWhr/yr = 8.2 kWhr/12 hour day = 0.683 kW on average.
0.683 kW / 13.7 m^2 = 50 W/m^2

@ 22.4% efficiency, that assumes an average solar radiation intensity of 50/0.224 = 223 W/m^2. You can see from the following map that only the desert Southwest U.S. meets that criteria.

The average for the U.S. is about 180 W/m^2, so a more realistic expectation of this system's performance for the country overall is:

2400 kWhr per year (not 3000)
9700 miles/yr (not 12,000)
26 miles/day (not 32)

Those in the desert Southwest would see the better-than-average figures stated in the article. Those in the Northeast would see considerably worse than this average.

RE: Only in the desert Southwest
By MrTeal on 8/12/2011 10:53:52 PM , Rating: 3
I think your numbers are incorrect.

1) You're off by a factor of two due to the length of the day.
Based on this solar constant, the mean flow per meter squared reaching the spherical outer surface of the atmosphere can be calculated by dividing this value by four, giving a value of 342 W/m2. In fact, the total amount of incoming solar energy continuously being intercepted by the planet Earth is equal to the value of the solar constant (1,368 W/m2) multiplied by the surface area of an imaginary circle whose radius (R) is equal to the radius of the Earth. Since the Earth is a sphere, the mean flow distributed throughout the whole of the sphere is four times smaller.

The numbers you use already average the solar energy only shines on one side of the Earth. So, you shouldn't be factoring in a 12 hour day.

2) The 180W/m2 average you quote accounts for the average incoming energy (342W/m2), subtracting the 77W/m2 that is reflected by the atmosphere (correct) as well as the 30W/m2 average reflected by the ground (incorrect). The losses due to ground reflection would already by taken into account by the efficiency of the panels, so you shouldn't count it twice.

3) Looking at the map you linked it looks like it assumes W/m2 normal to the surface, since it drops of substantially at higher latitudes. If that's the case, you can get higher energy production than you'd assume looking at that map by angling the panels to your latitude.

It's your link, so correct me if I'm reading it wrong, but the numbers linked seem reasonable. It averages out to 342W over a full year from an installed capacity of 2500W, which is a capacity factor of 0.14. That's typical of a solar installation in Massachusetts. Solar in Arizona can be 5 percentage points higher.

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