"Give me enough sunshine, and I'll juice a brick!" Jay Campbell c. 1993 Jay Campbell Albuquerque's incorrigible solar pioneer, Lu Yoder, has done it again. He has conceived, designed, built and put into operation a unique one man solar-powered business. His latest venture, aptly named "Sun Squeeze" is a mobile juice bar. Powered by a 65 Watt self-contained solar system, he produces fresh fruit and vegetable juice wherever thirsty crowds gather. Moreover, the entire rig is built onto a bicycle drawn trailer, so he can take it noiselessly & pollution free to wherever business might be. Lu's colorful background includes a stint studying Mechanical Engineering, years building and selling bicycle trailers, lots of experimental designs of solar electric and solar thermal systems, a couple of solar refrigerators, and uncountable other small projects. He first earned the attention of HP's readers with his prize winning solar oven (HP#31). This project has combined several of his experiences into one overall winning combination. The System Lu's system uses 2 used Arco 16-2000 32.5 Watt panels to charge two 12 Volt, 30 Ampere-hour, lead-acid gel cells. Solar power output runs from the battery through a Trace 812SB inverter and into the commercial grade Champion juicer. There is a voltmeter mounted near the business end of the cart, so that he can monitor the battery's state of charge as he works. Being a compact system, wire runs are miniscule. A 200 Ampere fuse protects the batteries and inverter, and a smaller fuse protects the batteries and charge controller. The cart is divided into 2 major compartments. One contains the electrical equipment and a 5 gallon solar assisted hot water tank for hand washing. The other compartment is for food storage (in an ice chest), cups, juicer, and literature on community events - the business side of the business. The housing is all wood, and colorfully painted by a friendly Santa Fe artist, Julia Coyne. The solar panels are hinge mounted to the top of the cart, allowing Lu to adjust them through the day for maximum charging. The whole rig (all 400 pounds of it) sits on a 4 foot x 4 foot steel trailer frame made from scavenged bicycle frames and electrical conduit. The panels fold down flat, and everything else fits inside. The frame is the same basic design that Lu has used for years, but is about twice the normal size, and beefed up accordingly. Use When a customer orders, Lu slices up the appropriate ingredients on the stainless steel work top, flips on the juicer, and tosses everything in. The juice pours out the bottom, and all pulp is diverted to a waste bucket. After the sale, he washes his hands in the hot water and is ready to start all over. He's still waiting for the day he has to say "please wait a few minutes while the batteries charge". That will mean he has a line of people buying juice, one after another. The system has proved capable and completely reliable through the short and cloudier days of winter. Summer production will be a snap. The electrical capacity was sized to meet the single load. Initially, Lu made the mistake of believing the rating plate on the side of the juicer, and ended up with too small of an inverter. The current Trace inverter, however, seems to be working fine. The motor is rated at 1/3 hp, but a closer look at the plate shows that it is rated at 5.7 amps, and under load (carrots!) surges to 1000 watts. Also, the motor simply can't put out as much power with the modified sine wave it's being fed. The PV panels generate 260 Watt-hours on a good four hour day. One cup of juice takes about 3.3 Watt-hours (20 seconds x 600 Watts / 3600 seconds/hour = 3.333 Watt-hours) to squeeze. This is only an approximation - carrots obviously take lots more power than oranges, but with these numbers he can max out at 78 cups per day. Of course, by starting the week with a full charge and ending with a low one he can exceed this amount pretty handily. It takes about 3 minutes to recharge from each cup of juice. The 4 hour limit was imposed by the health department. If he cleans the juicer and gets fresh produce, he can go on for 4 more hours. The water system is charged up with hot water in the morning, and then kept piping hot with a simple double reflector system. Pressure is provided with a foot type air pump Ä another of the clever touches in this whole system. After he closes up shop, he pedals over to 20 Carrots (a local juice bar/produce store) to clean the equipment and stash his food. Health department regulations make this easier and more practical than subjecting his kitchen to inspection. The cart is taken home and locked up. The inverter is removed and taken indoors for protection from humidity. Albuquerque does have a 5 month freeze season, so care must be taken to keep frost out of the inverter. Why didn't he use a 12 Volt DC system and reduce the initial outlay and complexity? For several reasons tied to the educational goals and versatility of this cart, that's why. There simply aren't equivalent juicers (or many other items) available in 12 Volt DC models. He would have had to rig a 12 Volt motor with belts to a gutted 115 vac juicer, which would look like some crazy contraption. He wanted to present the image of solar power driving mainstream applications, not some uniquely modified equipment. With the full system he can explain the process for producing home power, and help people to 'click' that it really does work here and now. Also, the cart can be used and expanded to drive any other electrical equipment that may be needed for work away from the grid - construction, repair jobs, whatever. Certainly a 12 Volt only system could be made for this application, but it wouldn't provide all the same benefits. Money Parts of the system were donated or loaned by some local businessmen. A local juice bar, 20 Carrots, provided the juicer and a blender (not yet in use), business experience and a commissary service in order to meet health department requirements. Construction was allowed in the shop of Zomeworks, a large Albuquerque solar equipment manufacturer. They also donated the batteries. The owner, Steve Baer, has always been known to encourage such independent thinking, and his support has been important to the success of Sun Squeeze. Solo Power financed the solar system, helping to keep the initial expenses low. Labor was provided by Lu, and materials were salvaged (recycled?) as much as possible, so there's no solid accounting of what this particular prototype cost. It is estimated that the total cost to duplicate the system with new materials would be about $2,000. The only ongoing expenses are for fruit & veggies, cups, taxes & vendor fees. He charges from $1 to $1.50 for a cup of juice; sometimes this depends more on how someone talks to him than what juice they buy. With him it pays to be curious, interested and nice. The cart passed a health inspection and is licensed to operate anywhere in the State of New Mexico (should he want to pedal out into the countryside ...). There are tentative plans to duplicate the system to cover the downtown, uptown and University areas, as well as for special events. Lu usually spends the workweek at the main campus of The University of New Mexico. Weekends have been tried at some local sporting goods stores and soccer fields. Business has been growing steadily, as he learns how to promote the product more effectively. He does have a small loan to pay off the panels, but is able to make ends meet at the end of the month. One of the accessories he's talking about is to hook up a pedal powered generator or juicer for customers who want to 'squeeze their own'. There would, of course be a discount for them ... Also, due to his support of sustainable agriculture he plans to shift the type of produce he uses. He will be using as much local and organic produce as possible when harvest season comes around. Conclusions drawn Once again it has been shown that solar systems are effective for niche applications even when grid power is available. Lu has launched this venture with equal hopes of making a little money and of exposing people to the potential of solar power. He is succeeding with both goals. As the sun climbs higher into the sky, he will add solar cooking demos and more educational literature to the operation. Anyone in the food business can tell you how much trash is generated by it. Sun Squeeze, however produces a remarkably small amount. Fruit crates are recycled, pulp is composted and the only significant waste item is paper cups. Some of Lu's regular customers are now bringing their own reusable cups, so even that is decreasing. Coupled with the bicycle trailer, this really is a low impact business. One of the intangible advantages to this system is that Lu only has to go out on nice days. He gets to talk to a lot of people, teach about solar technology, excite some people and generally make some money doing something healthful and harmless. One day a group of elementary school kids happened by on a tour, and the teacher asked that he explain how the system worked. Lu responded that he would not only tell, but would show, tell and taste. The kids started chanting "show, tell, taste, show, tell, taste", creating a bit of a scene. That has now become his motto for promoting this unique solar driven business, and solar power in general. Just listening to the comments customers make is motivating - "this is great!", "we need more of these", "I really love what you're doing", "carrot - kiwi is my favorite!" and on and on. The positive energy is really flowing around this venture. SHOW, TELL, TASTE! Specs INSERT SPECS TABLE Access Author: Jay Campbell, 218 Dartmouth SE, Albuquerque, NM, 87106 ù 505-256-1261. Lu Yoder, 315 Harvard SE, Albuquerque, NM, 87106 ù 505-265-3730. Zomeworks, 1011-A Sawmill Rd. NW, 87125 ù 505-242-5354. Solo Power, 1011 Sawmill Rd. NW, 87125 ù 505-242-8340. 20 Carrots, 2110 Central SE, Albuquerque, NM, 87106 ù 505-242-1320. Lu Yoder and Jay Campbell met through HP, when both were winners in the Indigenous Materials Solar Cooker Contest. Until then, they had been tinkering on similar projects only a few blocks apart, completely unaware of each other. This article is the first joint venture by them.