APRS Solar PHEV
APRS Solar PHEV
Solar Plug-In-Hybrid-Electric Vehicle. . . . Power to go.
See video at the Wash DC IEEE PHEV Convention 2007.
See Solar Prius power point presentation.
See Prius as an Emergency Power Station.
This car at the Wash DC Auto Show.
SOLAR-PHEV: . These high quality solar panels can provide as much as 215 peak Watts
of power good for about 1.7 KWh of free electricity
when parked for 8 hours in the Arizona sun. . Unfortunately, only 0.8 KWh or less is
available from the average Maryland Sun. . Where you live and the season of the year
makes a difference as can be seen in this plot of annual solar flux:
But 200 watts of solar panels, equates to about 1 km of electric
range for each hour of full direct sun (about 200 W-Hrs) after being stored in the battery
and used.
PURPOSE - Power-to-GO: . The value of this conversion is putting solar panels where they can be more useful than stuck on the roof of your house. As an augmentation to vehicle fuel economy, they may only gain 10 to 20% in MPG. And like many other solar energy projects or PHEV conversions for hybrids, this investment has an indeterminate cost-effective break-even point, because it solely depends on how much you need electrical power when you are far from the grid. Solar Power portability gives peace-of-mind where there is no gas or plug-in electricity available. Or for 8 hours all day parked at work. See more about Prius Emergecny Field-Day Power. As an aside, field work involves a lot of overnight accomodations in the Prius-Inn. See my Prius Inn accomodations for one.
More photos of the final installation after 6 months: Roof Rear, Front, Driver corner, Side and Hood,
Payback: . If you can take solar power where you need it, then its value can be far greater
than 10 cents per KWH. . And if you need power in the field, and don't have any, then solar
power is cheap at any price. . Just consuming it in the Prius is an equivalent
payback 30 cents per KWH which is better than the 10 cents at home.
The incentive for this conversion comes from the simple
economics of solar power:
COST: . We can provide these custom curved aerodynamic solar panels for about $2500 and $800 for the added battery capacity. Existing PHEVs only need the solar panels and charger. As noted above, adding Solar to a PHEV is not fundamentally economical for improved miles per dollar. But it is far more cost effective than the $2500 back-seat- headrest-video displays being sold by other dealers to rot the brains of your kids! Even a full PHEV conversion that will improve fuel economy from 50 MPG to 100 MPG is only going to save the driver of a 15,000 mile per year car, about $600 per year for $4 gas. . But neither is that the point either. The point is to reduce our dependence on foreign oil! And with the Solar conersion, the advantage is greater payback for your solar power investment and power-to-go wherever you need it.
PHEV BATTERY: . The primary purpose of the PHEV battery in this conversion is not so much to guarantee longer range on electric alone, but to have a place to safely stuff the solar power without any risk of overcharging or over cycling the original Toyota HV battery. . The photo at right shows my added 9 Amp-Hour cells in the wheel well prior to being wired together in series.
The discharge controller feeds power into the Prius to extend gas mileage but at a low enough rate (half hour) to not confuse the Prius computers. Also, the controller will not waste energy from the OEM battery back into the PHEV battery. The only time the PHEV battery is charged is during regenerative braking, from solar power, and from over night plug in. The batteries are designed to be cycled to about 50% yielding a lifetime of about 2 years.
Bottom line: . If you are going to invest in solar power anyway, you may as well put it on your car where you can use it to offset the cost of gas and where you can take it with you wherever you go or might need it, Field events, emergencies, or just watching the kids soccer match... This array has been designed to aerodynamically and asthetically match the Prius for maximum economy.
ANALOG INSTRUMENTATION: . The retro analog instrument panel shown to the right keeps me well informed of not only the power going into and out of the HV battery and solar panels, but also the economy of the gas engine via a tach and vacuum gauge. . The left meter is 150 to 300 volts and the right one is -50 to 0 to +100 amps. . (click for full size image). . This simple instrument panel is much easier to use than having to use a laptop for such displays. . The APRS ham radio below the dash is not related to this conversion but with an attached GPS provides tactical situational awareness of the positions, status and messages of similarly equipped mobiles in the surrounding area. The APRS network is linked to the internet and so you can always see where I am. Or using APRS, you can see where all the other Ham radio operators are with their bybrids.
IEEE Conference on PHEV Technology, Washington DC, 19 Sep 2007: [IEEE conference link]
My Do-it-yourself Solar PHEV was invited to this meeting in contrast to the commercial Plug-In Hybrid Conversions that were prominantly on display. We were offered a free $25 parking space. (Mine is the second from left). Only problem was, that no one told the parking lot zombie, and it took us an hour of wrangling to get out of the valet parking lot after it was over!
The other three Prius had 5 KWH or so(?) of added Lithium PHEV batteries costing several thousand dollars? . In contrast, my 2 KWH Lead-Acid batteries only cost about $500, and mine was charging the whole time parked in the sun, while they spent the first hour trying to find a place to plug in. Well, actually, the other Prius just plugged into 115 convenience outlets, but the E-BOX to my right was all electric and they had to find a 240 volt 50 amp outlet to plug in. They drove 100+ miles from Deleware on all-electric and the box was thirsty.
As I was driving away, a photographer came over and did a quick interview. . (Frame at right). Although he completely missunderstood the 80% State of Charge, he did capture some of the gyst of what I was saying See his video.
VEHICLE-TO-GRID: . Look carefully over the shoulder of the T-shirt guy and you will see the portable electric meter they take with them. Because, you see, the Ebox can both SOURCE and SINK energy. This demonstrates the Vehicle-To-Grid technology which has some real interesting promises for meeting peak power demand.... That is, if 75% of the Vehicles in the USA were PHEV's, then the installed instantaneous POWER capacity in those 150 million cars sitting in their parking lots all over the USA, represent FIVE TIMES the entire Electric Generating Capacity of all USA Generating plants combined!
Yet charging those 150 million cars overnight only takes 7% off the power grid at night when there is excess capacity. They estimate if we can figure out how to signal demand and pricing info to those 150 million cars, then the utilities would be willing to pay as much as $2k to $4k per car over the life of the car, to take back a few % during peak demand the next day... (I hope I got the facts right?)
Mild Solar Hybrid: . This second Solar Hybrid concept attempts to reduce foreign oil dependence by improving fuel economy on a 1996 Geo Tracker. I call this a mild hybrid because it shifts some of the mechanical loads from the gas burning internal combustion engine to electrical loads and then uses solar power and plug-in techniques to make up the difference. Simply loosening the alternator and removing the fan belt improved gas mileage almost 15% from about 29 to about 33 MPG.
Of course, this eliminates the fan and water pump cooling, as well as the alternator. To mitigate the losses of these systems, a thermostatically controlled electric water pump and fan had to be added. Extra battery capacity in the form of a marine deep cycle 12 volt battery also had to be added as well as a solar panel to replenish the electricity consumed on the way to work and then a simple plug-in 12 volt battery charger (1 amp) for use at night to make up for the trip home. The solar panel is only duct taped to the hood, since the car was handed down to us from my father-in-law, and my wife wont let me drill any holes in it or make any irreversable mods.
This car is a commuter car (15 mile commute, no-expressways) so its daily usage is well known and works reliably in this mild-hybrid configuration. But pushing the envelope towards multiple trips, long distances, prolonged night time driving, or rain conditions can add substantially to the electrical load and add risk to the total electrical capacity.
The Prius Inn: I believe it was *Hobbit who first used the term Prius Inn to describe the overnight accomodations for one in the right side of the Prius. Shown below is my rendition using a system of two overlapping plywood pads with strong support so that they can be used either in the full size arrangement for those over 5'6" who like to sleep flat, fully extended but with the rear seat removed, or in the short configuration by just lowering the front seat.
The full size arrangement above provides plenty of leg, elbow and head room and involves a third pad in the center to extend the bed to a full 6 feet 2 inches in length. Although this necessitates removing the back seat (two easy to reach bolts), it is a very comfortable. By extending the length with a center pad, the original short-configuration pads with their plywood supports can still be stored in only 37 inches of storage space. Unfortunately on the day I got around to taking photos, I just happened to have the center console out, so this photo is actually not representive of normal use. Normally the center console is there.
The short configuration shown above has the rear pad overlaping the forward pad's plywood base for strong support. This configuration has the advantage of not having to remove the rear seat and find a place for it (or leaving it at home). A wood support for the back seat supports the rear pad level with the front pad as can be seen in this rear view .
ALTERNATIVE ENERGY: We can do it. Just reducing our oil demand by 25% will prevent $200 MILLION per day from going to the destabilization of the Middle East. That keeps a lot of money out of the hands of the terrorists. Shown to right is my daughter's high school environmental project using a solar panel and a car battery to run her room off-grid. In the tree you could also see my ladder going up to where I hope to install my 400W wind turbine for backup emergency power and a small contribution to energy self sufficiency.
PRIUS #2: . My salvage Prius #2 needs some rear-end work. . But to my surprise, the Code of Maryland does allow a wood 2x6 to be used as a bumper as long as it is made from hard wood with a 3/16th inch steel re-inforcement. This will be my 2009 project.
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With a little hammering and some wood, I hope to build a pick-up rear end. The
big gain will be replacing the rear hatch with a solid plexiglas contour. This
new hatch will give 20% better visibility, eliminate the rear-view blockage
caused by the spolier, eliminate the sun-blocking tint, and allow for another 100
watts of solar panels in the bed of the trunk. These solar panels are out of
sight for driving, but tilt-up when parked. The up-tilt not only eliminates shading,
but can give good sun angle to the south in the winter.
Although aerodynamics will suffer, this car is intended
as the local drive-around town commuting car which in my case rarely gets above 50 MPH.
And besides, starting as a salvage vehicle it only cost 1/3rd the going rate.
TOWING: Towing the Prius on anything other than front wheels off the ground is not recommended. However, for moving my projects around the neighborhood and back (wife won't allow unfinished projects in the driveway), I made a small tow bar that configures to the front bumper hook and allows me to tow the unregistered Prius to and from its nearby hiding place as shown below:
The parallel angle irons extend beyond the pivot point to maintain solid contact with the full width of the tow hook coming out of the bumper. This assures that there is little left to right movement so that the towed car will track the towing car. See the side view and a closer view. You can see that the bolt is tightly compressed to an internal spacer and 4 washers to keep the tight spacing for proper tracking.
PARKING PAWL: and then you have to put the towed Prius into Neutral. Which of course is impossible to do unless you can get it to READY state (and if you can do that, why do you need to tow it?). Anyway, get into neutral, set the parking brake and then remove the fuse under the hood that powers the parking pawl. Its a 30 amp fuse that I think it is labeled PCON MOTOR. You will get the red-triangle of death and check-engine lights, but they will go away (eventually) when you replace the fuse.
Bob Bruninga, WB4APR President, APRS Engineering LLC
