Appliances Q vac via inverter Q VDC from Batteries

Figure 1- Rancho Chatuco's Estimated Electrical Power Consumption

from pumps to bulldozers on site). This hulk of a unit is located some distance from the rancho's main house where no one has to listen to its considerable racket. Power Source Control

A Heliotrope CC-60 PWM charge controller is wired in series with the PV array. This unit assures that the batteries store as much of the PVs energy as possible without being overcharged. The Heliotrope controller was equipped with the optional thermostatically controlled fan for those hot Summer days in the Baja. For a complete "Things that Work!" review of this controller and how it works, please see Home Power #8, page 31.

Energy Storage- Batteries

Rancho Chatuco's battery pack is composed of twelve Trojan L-16W lead-acid batteries. The individual batteries, each 6 VDC at 350 Ampere-hours, are assembled into a pack of 24 VDC at 1,050 Ampere-hours. This battery pack is specified so that 20% of its energy is not routinely used. On this basis, the pack contains enough energy to power the system for almost four days.

Energy Conversion- Inverter/Battery Charger

A Trace 2024 Inverter/Battery Charger changes the 24 VDC, produced by the PVs and stored in the batteries, into 120 vac for appliance consumption. This inverter is capable of delivering 2,000 Watts output with surges to around 6,000 Watts. We equipped the inverter with the optional Turbo Fan kit: that extends its output by keeping the inverter cool on hot days. Other options installed in this inverter were the battery charger, digital metering package and the remote control. The battery charger deserves special mention. The Trace inverters are very sophisticated and intelligent electronic devices. The built-in battery charger senses when the generator is operating. It automatically does two things when the generator is running: 1) it stops inverting and starts recharging the batteries, and 2) it switches all loads normally supplied by the inverter to the generator. This battery charger allows the system to use the 120 vac engine/generator to recharge the battery pack when there isn't enough sun to do the job. This charger is capable of putting up to 50 Amperes at 30 VDC into the batteries. The charger is user programmable to fit just about any battery capacity and type. For a "Things that Work!" test of the Trace inverter/charger please see Home Power #8, page 29. System Installation

There is a lot more to a system than a pile of equipment. All these various bits & pieces must be properly assembled into a working system. Details like wire size and

Ramon Andrade, Martin Andrade and John Pryor bolt the PVs to the roof of the PV shed. The PVs were racked in sets of 4 using slotted steel angle stock. The angle holds the PVs off of the roof and promotes cooling and increases hot weather power output. Photo by Richard Perez

A view of the PV shed from a hill to its southest. The crew is busy soldering the PVs feeder wires to the main 00 gauge copper cable bus. All the construction framing came down after the installation was complete. The roof of the Battery House is visible on the left hand side of the photo. The actual distance between the Battery House and the PV Shed is 145 feet. The main hacienda is concealed by the trees at the extreme right of the photo. Photo by Karen Perez

A schematic of Rancho Chatuco's energy system. The left side of this schematic contains the 120 vac equipment and the flow of 120 vacelectricity is indicated by the arrows filled with wavy lines. The right side of the schematic details 24 VDC

electrical equipement and the the flow of 24 VDC is indicated by the arrows filled with horizontal straight lines. The schematic is divided into four vertical areas. On the top are the Power Sources making electricity. The next level down is Power Processing and includes the inverter and PV charge controller. Note that the inverter straddles the border bewteen 120 vac and 24 VDC- that's its job, converting one type of electricity into another. The next level down is Power Storage and is accomplished as 24 VDC by batteries. The bottom level is Power Use and details the different types of power consumption.

interconnection are critical. If they are not done right, all the money spent on the hardware is wasted. Victor asked Electron Connection to help his crew install his system. John Pryor, Karen and I went to Baja California to do the job. Before leaving, we corresponded often with Victor and worked out most of the details in advance.

Victor and his crew built a special building with a South facing, 32° sloping, roof. This building was constructed at the best solar site near the house. It receives sunshine all day, the only limits are the distant mountains. While Rancho Chatuco is going to use this building's interior as a tool shed, the real purpose of this building is its South facing roof.

The PVs were racked onto 1.5 inch by 1.5 inch slotted steel angle iron. Each length of angle iron is 6 feet long and a completed rack holds 4 PV panels. See Home Power #2, page 11 for full details on racking and wiring PV panels using this method. Five of these racks were bolted to the roof of the PV shed. We cut up the same steel angle to make feet for the racks. These feet make the racks stand away from the roof by about two inches. This allows air to circulate under and around the PV panels, keeping them cool. The PVs have greater power output and longevity when they are cooler.

The PV array is located about 145 feet from the battery house. In order to efficiently transfer the low voltage DC produced by the PVs to the batteries, we needed special low loss cable. We used 00 gauge copper cable with outdoor insulation. The 290 feet of this cable (two conductors) are capable of moving the 960 Watts produced by the PVs while losing only 20 Watts to resistance within the cable. This 00 gauge copper cable is 97.88% efficient at its job. If you're interested in the tech details of wire specification, see Home Power #2, page 33. Victor's crew already had the cables strung out over their handmade power poles when we arrived. Each conductor is mounted to the pole with its own ceramic standoff. The cables are separated by about two feet.

We wired the individual PV panels up with short lengths of 10 gauge copper wire with soldered #8 ring connectors. These ring connectors were attached inside the panel's junction boxes. Short feeders were wired to each set of two series panels (24 VDC). These short feeders were SOLDERED to the 00 gauge main cables. All low voltage connections, especially those exposed to the weather, must be soldered wherever possible. Mechanical connections are far too temporary and lossy for PV wiring. These 00 gauge cables then ran along the poles and delivered the PV's electrical production to the batteries for storage.

The battery house is really the center of this installation. It contains the 12 batteries, the inverter and the charge controller. The 00 gauge cables delivering the PVs' energy were connected to the massive power lugs on the PV controller. The controller in turn feeds the battery pack. The inverter was connected to the battery pack via low loss cables with SOLDERED connectors. Mechanical connections don't last long around lead-acid batteries. The battery acid eventually gets inside the connector and the entire cable assembly becomes corroded scrap metal.

We laid 3 sets of cables over the 112 foot distance between the battery house and the main house. The first set is composed mostly of 00 gauge copper (since we already had the tail end of a roll) with a piece of 6 gauge soldered into the cable set. These low voltage cables deliver 24 VDC to both the Sun Frost refrigerator/freezers in the main house. The second set of cables is 6 gauge copper and carries the inverter's 120 vac output to the house. The third set of cables is 6 gauge copper and delivers the engine/generator's power to the Trace's battery charger.

At the house, both the inverter and the generator are connected to the mains panel via what we call the "Big Switch". This switch is a

From right to left, John Pryor, Richard Perez and Goyo Villa solder the feeders to the main bus. Photo by Karen Perez.

Ramon Andrade seeks refuge from the wind to complete his soldering. On this day it was cloudy, cold and too windy to make good solder joints outside. Photo by Richard Perez.

double pole, double throw, knife switch capable of handling 100 Amps at 120 vac in an efficient manner. This switch allows the mains panel to be directly sourced by the generator when the engine is operating or by the inverter if the generator is not operating. This takes the load off of the transfer relay in the Trace (limited to about 3kW.) and makes the full 12 kW. generator power available in the house. The following diagram shows how the Big Switch is wired.

John Pryor and I had alloted 4 days for the installation of Rancho Chatuco's system. Well, we hadn't figured on the folks that worked there. And I mean WORK. Ramon Andrade, Martin Andrade and Goyo Villa were the main workers on this project. Even though they spoke no English and my Spanish has degenerated to ordering dinner, we communicated. After they watched us wire up one set of PV panels, then they correctly did all the rest. Ramon learned to make clean, bright solder joints using a propane torch (if you think this is easy, then give it a try on some 00 gauge cable

sometime). Everyone was curious about the system and wanted to know how everything worked. Fortunately Victor and Cynthia speak better English than I do and were able to translate the technical information. Anyway, instead of 4 days of hard work, this system was installed in 2 & 1/2 days of fiesta. System Performance

All these components function together as a system. While all PV/Engine systems have basically the same components, they differ greatly in the number and type of components used. It takes experience and knowledge to correctly specify a system so that it meets the electrical needs without overspending. This system works for Victor and Cynthia because it was designed for them. It's as personal as a hand made pair of boots. With this in mind, let's examine how this system performs.

The PV panels produce in excess of 5,000 Watt-hours on an average solar day at Rancho Chatuco. The number of panels, and thereby the quantity of power they make, is specified to almost exactly meet Victor and Cynthia's average daily power consumption. This is the most cost-effective way of using PV supplied energy today. Size the AVERAGE daily production of the PV array to equal the AVERAGE daily power consumption of the system's users. Let the engine/generator pick up the unusual situation of sustained cloudy weather or higher than normal power consumption. If this technique is used, then be sure to do a thorough and accurate estimate of power consumption prior to specifying the system's components. Without a good consumption estimate, you are flying blind.

We estimate that Rancho Chatuco will run their engine/generator about 390 hours per year. Generator operation will mostly occur during the cloudy days of January and February. While the battery pack stores 4 days worth of energy for this system, the almost daily PV input extends their AVERAGE capacity to 13 days. Some generator operation is built into this system. It is far less expensive to occasionally use the generator than it is to oversize the PV array and battery pack to handle the infrequent extended cloudy periods. What we've done with PVs here is push the generator into the background. It's still there, with all its high-powered noise, but now it's only used occasionally. Before PVs, Victor and Cynthia were putting over 2,300 hours per year on their generator. With the PVs making power, the generator will be run about 83% less time. And during these fewer hours, the generator is more fully loaded and more efficient because its power is being stored in batteries for later use.

System Cost

A breakdown of what the components cost is in Table 1. Shipping is included in the cost of the components. Note that the two Sun Frost products are included in the total, eventhough they are appliances and not strictly part of the power system. The category "Cables & Wires" includes ALL wiring and shows that the copper cable used to transfer low voltage is expensive. Also included here are the custom made battery and inverter cables used in this system. Copper prices are rising monthly, so give careful consideration to long wiring runs at low voltages, they can be expensive. The slot titled "Installation Transpo" is the cost of getting John, Karen and I to Baja California and back. Electrical parts includes: the big switch, various electrical boxes, plugs, connectors, the PV rack material, solder, shrinktubing, nuts, bolts, and other small parts.

With the PVs in this system, the bottom line power cost is $0.92 per kiloWatt-hour and the system will cost about $209. per year to operate. Without the PVs, the power cost would be $1.22 per kiloWatt-hour and the system would cost about $1,501. per year to operate. These cost figures are calculated over a ten year basis and include EVERYTHING. By everything, I mean every component, both refrigerator/freezers, each bit of wire, connector, gallon of diesel fuel, and our transportation to install the system. There are no hidden costs here.

Over a 10 year period, this system, with its photovoltaics, will save Rancho Chatuco about $12,920. This is compared to sourcing the

ITEM

Cost

%

2C

Kyocera PV Modules

$7,080.00

35%

12

Trojan Batteries

$2,940.00

15%

1

SunFrost Frig/Freezer

$2,870.00

14%

1

Trace 2024 + All Options

$2,067.35

10%

Cables & Wires

$1,896.30

9%

1

SunFrost Freezer

$1,723.00

9%

Installation Transpo

$754.00

4%

Electrical Parts

$359.58

2%

1

Heliotrope PV Controller

$201.75

1%

Misc. Shipping

$172.00

1%

TOTAL

$20,063.98

Table 1- A spreadsheet breakdown of this system's cost.

Table 1- A spreadsheet breakdown of this system's cost.

Kyocera PV Modules

SunFrost Freezer

Trojan Batteries

Installation Transpo

SunFrost Frig/Freezer

Electrical Parts

Trace 2024 + Options

Heliotrope PV Controller

Cables & Wires

Misc. Shipping

system with only the generator. After about 6 years of operation, the PV panels will have paid for themselves. And they start making FREE electricity from that time on. How long will the PVs last? Well, no one really knows, but Kyocera warrants them not to lose more than 10% of their output power within 12 years. See the "Thing that STILL Work!" article in this issue for proof of the PVs' longevity.

System Overview

The first morning that the system was operating, Victor was beaming at breakfast. That morning, for the first time at Rancho Chatuco, he had a light over the bathroom sink to shave by. Victor, a sensible man, had never fired up the monster generator just so he could have a light for shaving. Well, this morning he had an illuminated shave while Cynthia cooked fish, rice, beans and eggs for breakfast in a kitchen lit by solar energy. Cynthia was also making plans around her sewing machine, another appliance too small to normally justify starting the generator. The two Sun Frosts were quietly percolating, keeping all the Rancho's homemade food fresh. With or without electricity, the grits at Rancho Chatuco are the best! John and I hardly had time to work between meals. Solar energy fits right in at Rancho Chatuco. Everything else there is solar powered... If God really does have a favorite place on Earth, then it may just be Rancho Chatuco. Ripe tomatoes volunteer in the orchards, all the animals there are fat and happy, and the folks, well, they beam like sunshine. Nuff said.

Where the Bucks Went.

The folks at Rancho Chatuco in front of the main hacienda. From left to right, Victor & Cynthia Rubio, Sandra, Richard Perez, Ramon Andrade, Goyo Villa, John Pryor and Martin Andrade. Photo by Karen Perez.

Access

System Owners & Operators

Victor & Cynthia Rubio C/O Home Power Magazine POB 130

Hornbrook, CA 96044

System Specifier, Vendor & Installer

Electron Connection Limited POB 442

Medford, OR 97501 tele: 916-475-3179

Photovoltaics Manufacturer Kyocera America, Inc. 8611 Balboa Avenue San Diego, CA 92123 tele: 619-576-2647

PV Controller Manufacturer Heliotrope General, Inc. 3733 Kenora Drive Spring Valley, CA 92077 tele: 619-460-3930

Battery Manufacturer Trojan Batteries, Inc. 22 Loomis Street San Francisco, CA 94124 tele: 415-826-2600

Inverter Manufacturer

Trace Engineering 5917- 195th N.E. Arlington, WA 98223 tele: 206-435-8826

Refrigerator/Freezer Manufacturer

Sun Frost POB 1101 Arcata, CA 95521 tele: 707-822-9095

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Getting Started With Solar

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Do we really want the one thing that gives us its resources unconditionally to suffer even more than it is suffering now? Nature, is a part of our being from the earliest human days. We respect Nature and it gives us its bounty, but in the recent past greedy money hungry corporations have made us all so destructive, so wasteful.

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