The system described below was first online on March 5, 1998. Our five year anniversary passed in March 2003. As the French say, the more things change, the more they stay the same. The big change in the electric power industry was the deregulation of generation and distribution in California and the subsequent expolitation of the marketplace by energy producers and traders. The constant is that the liars, thieves, and incompetants are still in charge and busily picking our pockets. In fact, our Governor (Gray Davis) recently appointed a term limited politician to be the Director of California's Department of Finance (an important position as our state has a deficit of 22 to 35 billion dollars). The new director? Ex State Senator Steve Peace, the architect of California's failed electricity degregulation scheme! Back in 1998 some of us were concerned about the popularity of SUVs and now we have General Motor's Hummer 2 - which is now being marketed to young women who are being told that they should "put on something a little more metal" (despite the fact that they are far more likely to die in a single vehicle rollover than in a sedan - this since these high and tippy SUVs have notoriously weak roof structures despite a carefully crafted and illusional solid appearance). In 1998 we were concerned that dependence of foreign oil would drain resources from health and education into the military and industry. Now, contrary to international law and the norms of civilized nations our president George W. Bush has "reluctantly" chosen to spend hundreds of billions of dollars to crush (and then rebuild with contracts to contributors and cronies) an oil rich country (Iraq) and to control its region while a nearby city (Oakland, California) must choose to either close seven of its 14 libraries or keep them locked four days a week. Another (Berkeley) has sent layoff notices to 25 percent of its teachers, including 13 of 19 at a "magnet" school targeted for minority students. And now, the Californa Public Utilities commision is proposing to impose a "departing load" charge upon solar and wind instalations under the rational that the revenue bonds written to support the expensive long term electricity purchases by the Department of Water Resources must be paid for by all ratepayers. This is not based on the load displaced but on the power provided, even if it is for new load and the power provide is peak power and the load is off peak. How stupid can they get? Undoubtedly they will top even this! As Lilly Tomlin said: "No matter how cynical I get it's never enough." But if you are reading this, you probably already are aware. "If you aren't outraged you're not paying attention!"
Right: Easterly view of trackers from roof of house with Mount Diablo in the distance.
Below: Westerly view toward back of house from court.
Current developments in higher efficiency panels include thin-film devices at 15 percent (with low production cost but limited lifetime at present), laser remelt of polycrystalene cells to obtain 20 to 25 percent efficiency, and rumored laboratory microlithographic devices using dipole antennas of lightwave scale with 70 percent efficiency. While the presently available 20 to 25 percent efficiency devices would be very desirable for an upgrade to this installation, the high cost currently makes them suitable only for space satellites and planetary probes, where the high cost can be readily justified by lower launch weights.
March 2003 - Here we are 5 years out and there has been no real progress in efficiency. My plans were to replace the low efficiency panels on the trackers about now. Predictions are that it is 15 years out before we will see higher efficiency. So rather then upgrading the trackers we are having additional capacity added to the house roof. This will have the additional benefit of shading the most solar exposed portion of the roof, an aid to comfort on those hot summer days. There has been one substantial improvement in the technology. With the use of a new type of inverter (the Sunny Boy), panels may now be connected in high voltage series strings that greatly simplify and reduce the cost of connecting the panels to the inverter. This enables the use of easily worked 3/4 inch conduit and number 10 wires and is ideal where the panels are distributed over several locations on the roof (provided the panels have the same orientation and shade timing or are organized into similar parallel groups). Because of its sophisticated internal protection software it is practical to build an "overloaded" system that gets both morning and afternoon light through separate panel systems. This is suitable for a piched roof house aligned on a north-south axis. With time of use net metering it can be advantageous to align fixed solar powers to the west, rather than the south which will produce the most total power. The western orientation produces more power during the peak afternoon cooling time.
March 2003 - Increased subsidies for 2002 and 2003. are now $4 to $4.50 per AC watt. At the five year anniversary of the legislation it was about to expire without additional approval by the California Assembly and Senate. Believe it or not, the utilities lobbied against this renewal, claiming that the poor ratepayers were cross subsidizing solar (not that I consider that a bad thing). Analysis showed this subsidy to be about one penny a year per ratepayer. The limitation on installed base is still a meager 1/10 of one percent of total system capacity. I really don't understand the utilities motivation for being against end-user distributed solar and wind except that perhaps they might feel a loss of control (of their hand in my pocket).
The new regulations also allow wind power and combined photovoltaic and wind power systems to qualify for net metering.
Annual Net Metering - it works for the homeowner and for the utility.
On the other hand, the current electric rates do not include costs that are "externalized" by the power producers, such as the medical costs associated with pollution related disease, government handling and storage of nuclear wastes, damage to crops from acid rain, global consequences of climate changes due to carbon dioxide, or destruction of rural and wilderness environments from strip mining and impoundment flooding. If these and other costs were reflected in the price of electricity, then solar electric would likely look like a bargain by comparison and wind power would be a "no brainer".March 2003 - With the sink in interest rates, combined with the results of depredations of Enron, El Paso Gas, Williams, etc., etc., and the response of our government (our Governor signed long term contracts when prices where highest) home solar power is now even more attractive. Some computations show that an investment in solar power is equivalent to 3.25 percent taxable interest on a Certificate of Deposit.
Also, the price of electricity is expected (by the conventional wisdom promoted by the deregulation interests) to fall in five to ten years with the ratepayer payoff of the "stranded costs" of uneconomic nuclear power and pumped storage. Given expected economies in the extraction and transport of coal and the willingness of our elected officials to fold under the lobbying pressure and financial muscle of powerful and rapacious extractive companies (such as Peabody Western Coal and its related companies) it looks like we will be dealing with coal power for some time.March 2003 - Looks like the powers in charge have "No Brains", when you look at their DECLINING support for alternative energy research and development and their continued (and even increasing) subsidizing of conventional energy production methods. Of course, our representives deny that the flood of money to their campaigns and parties has even the slightest influence on the appropriations, taxes, and regulations they vote for - does anyone believe that?
Note that the economic foundations of the people making claims of lower future rates are the same ones that said our cable TV rates would fall under the pressures of competition (they are going up at twice the rate of inflation).March 2003 - Well, well, well - look what happened to energy prices! Since second tier rates in California are now over $0.15 per KWH and interest rates are now the lowest in years, SOLAR POWER IS AN EVEN BETTER DEAL! (Even partial replacement of household energy replaces the highest cost electricity first.) Load shifting is the moving of energy demand from high cost time of use to low cost. For air conditioning, this would involve chilling water during the late night and early morning (12 midnight to 6 A.M.). This not only uses lower cost electricity, it is also much more efficient as the heat is being rejected into a lower temperature atmosphere. This cold water is then used to chill air (or the interior structure of the building) when it is needed during the heat of the day. At this time, the solar panels help shade the roof from the sun and produce electricity that is bought back at up to seven times the cost of using it at night. The recharging of an electric vehicle is an easily shifted load, although this works much better with batteries other than the low cost lead-acid type. By combining time of use net metering with load shifting, it should be be practical to satisfy a household's needs with a system of modest size.
Large wind turbines are presently almost as cost effective as coal, have the advantages enumerated above for solar, provide a great amount of employment per watt installed, and could be the preferred national power source but for the political clout of these entrenched interests and the narrow and short term views of members of our government, fostered by our absurd campaign financing methods and unwillingness to make the broadcast industry pay back for its spectrum usage with free time for candidates.March 2003 - Now cable TV rates are going up at MORE THAN THREE TIMES the rate of inflation! (Ours went up over FIVE times the rate in 2002.) For this we can thank the regulators which allowed AT&T to buy our cable provider (TCI). AT&T then scrapped its plans to deliver cable like services through fixed location microwave. (Studies have shown that cable rates are 17 percent lower where there is competition.) Now AT&T has sold out to Comcast. So what can we expect? What has happened in the past is that the new owners first say they will "invest" to "improve" the system (actually so they can deliver more extra cost services such as pay per view and extra cost "digital" cable) and then raise the basic rates to pay for this so called investment.
If on-grid solar isn't economically practical right now, why do it? Probably for the same reason some people buy four wheel drive Chevrolet Surburbans that never see mud or snow and seldom carry more than the driver alone to the convenience store two blocks away to buy one pack of cigarettes - it looks to the buyer like a worthwhile thing to do, however impractical. Unlike the more expensive Suburban, however, PV power is on the correct side of any "green" ledger, costs almost nothing to operate, has an expected useful life of 30 or more years, and is incapable of crushing small cars.March 2003 - In the U. S., wind is now competitive with coal at the site of production, but we lack the strong national infrastructure needed to support our superior wind sites. In the late 1970s the U.S. dropped its energy crisis inspired subsidies and research for wind power. The government of Denmark continued to encourage these developments with a goal to generate fifty percent of their power with windby 2020. Danish manufactures now are the leaders in large wind turbines (10 to 30 Megawatt and larger) and are now exporting large turbines to the USA. This could have been an American industry. As far as the politics - more of the same and its getting worse! By the way - did you know that the profession from which members of the U. S. House and Senate come is mostly the law, while in Europe the largest parlementary representation is by teachers? Which would you rather have representing your family's interests as citizens? Which would you rather have representing your corporation's interests if you were a corporate executive?
Installing this kind of solar power can also be compared to making tax-free investments, even though the net return may be less than a taxable investment, simply because one doesn't want "them" to have the money. Not practical, but very satisfying for some.March 2003 - I now drive an electric vehicle (a 1998 Ford Ranger EV obtained in January 1999 at very favorable lease rates) - but I don't see many on the road. Both GM and Ford have terminated their electric vehicle development programs, despite the fact that they had people on waiting lists for lease and purchase. Not only that, but the Suburban has been outweighed by the Ford Expedition (which was unsucessful in the market and will not be continued) and now the ultimate in SUV excess, General Motor's Hummer 2. This is so successful that they have waiting lists and is so heavy that they do not have to publish milelage (said to be 11 miles per gallon). Our government in its tax wisdom will subsidize most of the costs of this monster for the self employed. This is an unintended consequence of legislation to encourage investment in medium weight work vehicles by tradesmen to boost the economy. Apparently the pols did not expect that anybody would buy a 6000 pound GVW truck for personal use - but we know that the manufacturers did as they plan years in advance, and they are often invited to assist the pols in writing the laws. So what is the Bush administration's latest? They intend to increase and accelerate the tax subisidies that can be applied to this vehicle!
Another way to look at the expense is that a substantial portion (40 to 50 percent) is paid off in avoided electricity costs within a reasonable period (15 to 30 years), and the remainder is strictly a personal subsidy to pay for its "toy" value or "bragging rights" (like that gas guzzler in your driveway).
January 2003 - Solar is an even better deal now!
A quarter acre (10,000 square feet) lot allows room for the trackers without crowding the house or yard.
March 2003 - We have not got the whole house AC yet, but can chill one room while not drawing power from the grid. With the addition of the new rooftop system (2.4 KWDC) the system now produces 20 to 25 KWH per day in March 2003) When paid of we expect to install several reversable heat pumps, freeing us from the high cost of natural gas heating in the cool season, increasing summer comfort, and powering our electric transportation. Not only that, we may obtain a zero net carbon usage.
We have occasional early morning and late evening coastal fog during the Summers, with correspondingly cooler weather, in some years for weeks at a time.
The trackers used in this installation are sensitive to easterly or westerly winds of over 25 miles per hour. Wind is not expected to be a significant factor in tracker operation. During summer, the site is sheltered from prevailing westerly winds by an adjacent hill. The only significant winds are from the South during winter storms. Smog and haze are usually significant only during the Fall season, when prevailing westerly winds are replaced with a slow north-east flow and particulate pollution from primitive fireplaces and agricultural rice straw burning becomes significant.
Local terrain and vegetation cause late afternoon shading but only an hour or two before sunset, a time when the solar insolation is reduced by the long path through the atmosphere.
These are favorable conditions for this installation, since during hot spells we have plenty of sunlight to generate power for air conditioning, lacking the hot, humid, and overcast conditions of Eastern states.
Equivalent solar hours are calculated by dividing a day's DC watt-hour production by the panel's peak watt production. If this done by measurement over several years it can account for local shading and weather conditions.
Initial results for sunny days in March through May show a typical midday AC current of 7.5 amps, producing about 1800 watts, substantially less than the design peak of (0.9*2340) = 2106 watts. Higher output is seen with certain sky conditions, such as high thin cirrus or passing fair weather cumulus. This lower production is probably due to the near sea level altitude and relatively moist coastal air.
Actual results for June and July 1998: We are producing a surplus of power, up to twenty kilowatt hours per week in late Spring and early Summer. Our weather has been relatively cool due to coastal breezes from the bay region, so we haven't needed much air conditioning. So now on a hot day we run the room air conditioner much more than we we would have in the past, since the most significant effect is to drive the meter backwards at a slower pace.
Actual results for August 1998: Hot days, but who cares? Hole up with the air conditioner! We have one of our rooms fitted with a very powerful under window unit. We run it for a couple of hours in the morning, pre cooling the walls and ceiling. Then the room is comfortable for the early afternoon without running the unit (nice and quiet). Later in the afternoon we run it as needed, still producing some surplus power.
Actual results for September and October 1998: The panels work more efficiently in cooler weather and with reduced A/C load we are still producing a small surplus despite the shorter solar days and increased use of lighting.
Actual results for November and December 1998: While no longer producing a surplus, the added solar power greatly reduces meter spinning, producing about half of the power we use.
Long term performance - 1999: Usage history through May 1999 was recently provided by PG&E. Of particular interest is the balance under the new annual net metering tarrif. In these late Spring months we are accumulating a credit of close to 200 KWH per month, owing to the sunny days this spring with the departure of "El Nino" weather. The weather has also been pleasantly and unusually cool, averaging about ten degrees below normal. This cool weather is expected to continue through August, so we should have a substantial energy surplus to use for both our usual hot weather between mid August and mid October, with enough surplus remaining to cover our our winter use. This indicates that the system as installed is the correct size for our present power useage.
January 2003 - Without the electric vehicle we would break even over the year. The vehicle represents about an addtional 50% annual load increase. This is not an especially efficient vehicle - about 0.5KWH per mile. With time of use net metering we would probably do better than break even as the EV can be charged at low off peak rates - but is that just gaming the system?
This contract prohibits resale of electricity to other customers, requires the keeping of a system log, and restricts the production capacity of the system to 10,000 AC peak watts. It also prohibits the use of time-sensitive metering, which is unfortunate since the production almost coincides with peak demand times. (Note: this may change under the new annual net metering when appropriate meters are developed.)
Output is 240 volts nominal, two wire, single phase. If converted to an uninteruptable power supply (UPS) at some future time this will require the use of an additional 240V to 120V transformer.
Competitive trackers require that the gearing be strong enough to transfer wind gust loads from the panels to the supporting structure.
Time: 0940 Local Daylight Savings Time Panel Temperature: 61 degrees Farenheight. Sky condition: thin scattered cirrus. Panel position: Tracking within 5 degrees. Solar Radiation: 894 Watts per square meter on panel axis. DC Watts: 1828 AC VoltAmperes 1711 Power factor not measured, assumed 1.0 From this we can calculate: AC Watts = VA*PF = 1711*1.0 = 1711 Panel actual performance: (panel rated wattage of 2340 is at 1000 Watts per square meter). 1828 / (2340 * (894 / 1000)) = .873 (probably due to 61 deg temperature) Panel performance is thus 87% of design maximum. Inverter efficiency: Inverter operating point 1828/4000 = .427 Inverter efficiency = ACW/DCW = 1711/1828 = .936 System efficiency: Collection area 17.86 sq meters Net system efficiency 1711 / (17.86 * 894) = .107 Consultant observations: The use of trackers keeps the panels much cooler than when closly fitted to a roof. Performance of non tracking systems at this time of day would be typically thirty percent of maximum. Owner observations: panels had not been washed recently, but were not significantly dirty, either. Net system efficiency of .107 is somewhat lower than the expected .12, but close enough for our purposes. Low inverter loading of .427 is only a bit above the peak inverter efficiency point. Operating at the optimal loading would give an expected inverter efficiency of .96.
Space under the trackers may be used for gazeebo or lathhouse. Check back in Summer of 2000 for further developments.
A limited uninteruptable power supply (UPS) capabilility may be installed at a future date to support a sump pump and refrigeration. This will require some site specific electrical engineering owing to unique requirements. This will probably require the use of an AC charging system for normal standby (battery float charge), with manual or automatic switching of panel output to a DC charge controller for emergency use. Current systems are designed for either "on grid", with no backup, or primarily "off grid", and so lack the sophistication desired for this installation.
BELOW: View of sun path instrument with reflective dome removed. A specific card is installed for the lattitude, oriented for compass variation. The compass is used to orient the device and a bubble level can be seen at the center.
RIGHT: View of sun path instrument in use. The environment is reflected from a dark transparent dome covering the instrument. The sun path lines on the card under the dome are inspected for intersections with the reflected image to determine shading at various times of year and day.
BELOW RIGHT: Image of sun path card. Curved lines represent sun path for different months of the year. Card is adjusted for compass variation by aligning the number at top with a mark on the instrument.
So now I had four choices on a second tracker unit:
1.) Match the unit I have - this will both stick up in my neighbor's sight line and intrude on walk-under head room (the original motivation for the poles was to avoid intruding on usable yard space).
2.) Find an available tracker and panel combination that will give me a ten by ten unit. Unfortunately, this is limited to 900 watts.
3.) Go to a smaller zomeworks tracker mounting two DG-300 panels and put the additional panels on the roof. Roof panels in 1998 would require extensive and expensive ground fault protection (see 4 below).
4.) Put 5 DG-300 panels on my roof and build my own tracker for subsequent panels (the original game plan was for two tracker units with subsequent roof panels). This is impractical since Trace does not provide an upgrade to a unit suitable for use with roof units under current building code, so the unit would have to be returned with a subsequent restocking fee. This restrictive code will be relaxed in the new code which will be effective in 1999.
We decided to purchase a second zomeworks tracker, but painted white to reduce its visual noise level to the nearest neighbor. Unexpectedly, the dampers provided were gloss black (Zomeworks just doesn't get the picture), so these were spray-can repainted with Rustoleum gloss white over white primer, after sanding the gloss black.
We do expect to modify the industrial appearance of the units. Use of the poles to support a vine trellis, potting house, pergola, or gazebo is being investigated. The visually severe edges of the panels may be softened with decorative elements and so transforming the devices into large kinetic sculptures (check back in 2000).
View into yard from back porch showing tracker units.
View of pole. Pole is 16 feet of 8 inch diameter, 1/4 inch wall steel pipe, terminated with a reducer and one foot of 6 inch diameter pipe. Top of pole is 11.5 feet above grade.
View of a single photovoltaic panel. Panel frames are 50.5 inches by 74.5 inches.
Closeup of photovoltaic panel showing polycrystalline silicon. This is where the sunlight is converted to electricity, which is collected by the metal traces on each side.
View of one of the two tracker boilers.
View of boiler cross connector shield on the low side of the tracker. A tube connects the boilers.
View of tracker shader/reflectors.
When tracker is not pointing at the sun, shading function will expose one side boiler, causing transfer of fluid in the liquid state to the opposite side, where it condenses, the additional weight causing tracker motion. The reflector function enables a grossly misoriented tracker to flip over (typically in the morning) to start the tracking process.
Overall back view of tracker.
Closeup of tracker pivot.
Closeup of damper. The damper stabilizes the panel against response to wind gusts and prevents overshooting during the morning flip.
Closeup of pitch arm. The pitch arm may be seasonally adjusted for better performance. Adjustment is by positioning the arm to a different bolt hole. This may be replaced with a homemade screw type device for adjustment from ground level.
Closeup of wire drops from panels to upper box.
Closeup of lower box on west pole. Large 1.25 inch conduit proceeds underground to house, routed around fruit trees and sanitary drain. Gray plastic conduits are stubs for future instrumentation or telephone.
Exit of conduit from ground at house.
Run of conduit along house to inverter.
Picture of trace inverter all weather enclosure.
Left: Interior of weather enclosure from the Direct Current (DC)side. DC feed is on the right side. Cylindrical object at top is a large capacitor, required when no directly connected batteries are used. Smaller tubular devices on rear wall of enclosure are fuses.
Right: View of Alternating Current (AC) side. Additional connections are provided for generator input and essential AC output when used as off-grid or emergency system. Conduit over top of unit carries AC wires to the disconnect switch.
Safety disconnect switch for use by electric company.
Additional 30 amp breaker supplies power to the buss bars in the service box.
Drilling a pit.
Pits were completely flooded by rainstorms and the water softened the walls. After pumping out the water a worker had to scoop out the muck at the bottom of the pits.
Bottom of pits are filled with chip stone for drainage.
Through rods prevent punch-through and pole rotation within foundation.
Five workmen erecting the pole.
Ready mix truck. 2.5 yards were delivered. Due to muck removal, additional concrete was required and was mixed on site to complete the pour. Interior of poles were filed up to the top of the base, where a weep hole allows condensate drainage and airflow to dry the interior of the pole.
BELOW: Technician securing conduit to pole
Electrician wiring panels to collector box.