Solar and wind energy system design/sales

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PHOTOVOLTAIC SYSTEMS (Batteryless vs Battery )

Click on the links below for additional system specials

Xantrex' new XW Sine Wave Inverter System. This system is a battery version that provides independent, utility intertie, and/or backup power.... A utility intertie battery system provides power during power outages....

BATTERY VS BATTERYLESS SYSTEMS....

Each system has its advantages... Obviously, with a batteryless system you will not have energy stored for power outages and you will not be able to use it for an independent system. Battery systems require added expense and added maintenance, but they can nontheless offer benefits: 1) Energy Independence for remote off-grid sites 2) Backup power for critical circuits for grid-tied systems during outages 3) Society in general may have a larger bargaining chip with utilities when systems that can run independently are installed.

Battery systems are more expensive to install and require periodic maintenance -- even replacement of the batteries. For that reason, backup power systems often employ as few as four batteries or less and often gel cell or absorbed glass mat batteries are preferred, since they do not require regular maintenance or equalization charging. They are less robust for frequent deep discharging than the liquid lead acid types.

For off-grid systems, many types of batteries are employed, and usually more of them. Liquid lead acid types are popular due to the lower purchase price and the ability to provide frequent discharges. For lower maintenance or longer life, high quality 'industrial' lead acid batteries should be employed. Batteries used in high use fork lifts are a good choice as well as Rolls/Surrette heavy duty types. Golf cart batteries can be used but expect limited service life of up to 6 years or less. Higher quality batteries are expensive but are the most robust and will last longer than other types of batteries. These batteries provide more power and can have a life up to 15 -- 20 years or more. (Gel cells or Absorbed Glass Matt batteries are near the same price as industrial liquid lead acid batteries. They can be employed in off-grid systems where owners wish to have as little maintenance as possible and where deep discharging is limited.) Lithium ion and Nickel metal hydride batteries show promise, but currently they are too expensive for most renewable energy system systems deployment.

As energy storage efficiency increases for these batteries and as the public learns to use energy more efficiently, battery systems will become more popular. Hundreds of thousands of energy conservative people world-wide live with independent systems. Currently, independent or grid interactive PV systems, require little maintenance other than adding distilled water to the battery bank and keeping the cable connections clean. And, wind systems are becoming much more reliable. Liquid cell battery systems require adding distilled water every few months. Deep cycle batteries are ALWAYS used. A new device from Battery Power Solutions is extending the life of wet cell batteries by providing an electronic pulsing technique to reduce sulfation which is the leading cause of wet cell battery failure. These can extend the life of wet cell batteries but the best way to extend battery life is to operate the system on the top 20% of available battery power. Deep discharges below 50% can shorten battery life. Never let batteries sit without a reliable battery charging system. They will slowly discharge and a discharged battery needs to be recharged immediately. Solar modules and wind generators can do a good job here. Automatic start fuel powered generators may sorely disappoint you if they are the only charging source. They may ruin your batteries when you least expect it. Fuel will run out; the start battery will run down; someone will accidently turn the auto-start system off. We even have one customer report that a mouse had eaten through his signal cable! You can leave your generator in autostart (a function that starts the generator in response to low battery condition) but don't rely on it as your only charging source. Note that automatic inverter systems using batteries have an automatic transfer switch that connects the utility (if one is present) or the generator when its up to speed to insure that the battery bank is charged. This will occur when the utility is present or restored after an outage or when a generator is started. This is a method of providing power to the battery charger if solar or wind resources are low. Generally, when powering remote homes and cabins, solar or wind resources are more than adequate to maintain a battery bank if the owner is gone (be sure the solar modules can get sun year-round) since energy use is minimal or none. Be sure to turn off all the loads!

'Battery-less' systems, on the other hand, offer a lower price and easier maintenance. They are becoming quite popular for those reasons. Batteryless systems are great for those wishing to lower their energy bills, especially if you don't need back-up power. Batteryless systems work best where outages are tollerable. They can also work side by side with a back-up generator set...... In this way, back-up power can still be provided even though the PV system may not have batteries. It should be noted however, that generators do not provide instantaneous back-up power, therefore, when used to provide power for computers, it may be necessary to reboot your CPU. Batteryless systems can use a gasoline or propane gen-set connected to a sub panel. One may have to be added to the main service panel WITH AN APPROVED TRANSFER SWITCH (and ONLY WITH) to supply back-up power during outages. When using a generator set, NEVER connect the generator to the utility under any circumstances. Use an approved transfer switch so that your loads only are connected to the utility OR the generator, NEVER both. Always have such an installation inspected by the electrical inspector to avoid the possibility of fire or other electrical hazards. This means "obtain a permit" before ANY electrical work is performed -- on-grid or off-grid.

If you have frequent or prolonged outages, a battery type system may be more advisable. An approved grid-tie battery system can also sell power back to the utility or reduce your utility bill through net metering, just the same as a batteryless system.

The sun OR the wind can provide your main energy source, depending upon the level of these resources in your location. In many situations, a hybrid arrangement that exploits both resources is a good idea, as the sun may be out and no wind present, and vice versa; the wind may be blowing but there is no sun -- depending on the day and the fortune that nature chooses to bestow upon you. And, there are days or hours when both are present. If you have a hybrid system, these energy sources compliment one another, providing useful energy when one resource may be low or unavailable. A hybrid system can often contribute a much larger or even total energy contribution. Many wind systems below 10 kW require at least a small battery bank. There are now wind generators that have batteryless inverters. This wind systems are rated at 1,800 Watts, 3,000 Watts and 10,000 Watts and will deliver significant power if you are in an area that delivers a 13-14 mph plus AVERAGE wind speed (this is a pretty high and steady wind!). Anything below 12 mph will deliver only minimal power (except when storms are blowing in and out!) Therefore, in many areas, wind is a good energy supplement to solar.

Batteryless inverters are designed to connect to solar PV panels OR wind generators -- not both -- therefore one 'batteryless' inverter is required for each type of system. However, One 'battery type' inverter may be connected to both types of systems simultaneously. The reason is that the batteryless inverter has a controller built-in and it can only control one source at a time. Most battery inverters, on the other hand, employ separate controllers (the controller is NOT built-in), therefore both systems can be simultaneously connected to the inverter. The Xantrex XW systems, Xantrex Sine Wave II, Xantrex Sine Wave Plus, Outback Flexware GTFX and GVFX inverters and combination systems are good inverter system choices for hybrid applications. These are entirely feasible and often employed for combination wind and solar PV systems.

For a battery type back-up power system or independent power system, you may have to resort to charging the battery bank with a gasoline, diesel or propane generator set during foggy periods or during a several day period with no wind or sun -- in the winter especially, for independent systems. For back-up power applications, it may be necessary to charge the batteries with a gen-set if the power outage is prolonged. I prefer to use fuel powered generator sets as little as possible. The use of generators to charge battery banks can be reduced by properly sizing arrays, windgenerators and battery banks, and also most effectively by initiating energy conservation practices -- especially when mother nature's resources are limited. A propane generator gives off the least pollution, as well as natural gas -- mostly water vapor and some C02. Running a generator set for a few hours per day to charge a battery bank IS FAR PREFERABLE to running a generator all day and all night long!!!! Note that the rising cost of propane and natural gas can cause fuel costs to be significant if not prohibitive! One non-solar customer reported that running his propane generator cost him $1,200 during a 10 day power outage! Many remote lodges still run diesel generators continuously. This practice is archaic, expensive, noisy, smelly and an environmentally destructive ritual.

Economics, utility stability and the weather often dictate the necessity of having a gen-set but they don't have to run all day and all night long! Some diesel manufacturers now claim low emissions. I would make them substantiate this claim before purchasing by comparing the emissions of such systems to natural or propane gas gen-sets by the results provided by an independent and certified testing laboratory (compare CO2, CO, NOX, and particles). Biodiesel, on the other hand, has superior combustion characteristics. Unfortunately, the availability of bio-diesel is limited in most regions, and its production is beginning to cut inot our food supply chain. And, the percentage of bio-produced fuel in relation to carbon fuels must be considered. Some bio-fuels have a bio to carbon based fuel ratio mixture of as little as 5% (even this helps!). 100% bio-fuel diesel engines have outstanding combustion characteristics but often the diesel engine must have Viton fuel hoses installed and in some cases the fuel tank must be heated to burn bio-diesel fuel. Heating the bio-fuel helps to increase its combustibility and to thin the fuel where it can be effectively pumped.

Gasoline generators are generally not very clean when it comes to emissions. You can purchase a propane or natural gas conversion for many generators (by special order). Eventually, the biofuel option could become viable if it can be produced from algae or other non-food agricultural sources, but then there could even be competition for land use that may contribute to risin food prices. Given our escalating global warming situation, I am in favor of NOT using a generator at all. At our home, we go into a "maximum energy conservation mode" whenever there is an outage, since we don't know how long our outages will be. We have successfully operated without running out of power and have even had enough power to share with our neighbors during prolonged outages.

In some locations there may be abundant sun but little wind -- a good reason for implementing photovoltaics for your major energy source. And, in others, a lot of wind but little sun -- a good reason for implementing a wind system as your major energy source. Or, perhaps local covenants may preclude installing a tower or other wind generator: This scenario may determine that PV is your major choice. (Check to see if your development covenants can be modified or exempted to promote wind and PV.)

The scenario below is ideal for urban dwellers in neighborhoods that may not allow windgenerators. However, we urge that cities, developments with covenants and others consider exempting or allowing wind systems to be installed due to increasing energy supply and global warming problems. They can be installed neatly and can be architecturally acceptable and even artistic, if done in a correct manner with consideration given to the context in which residential neighborhoods are designed. There are now a wider variety of wind system options available that address aesthetic and noise issues.

The "photovoltaics only" choice below is a simple one inasmuch as the utility grid is being used as the battery bank to provide power when the sun is not shining. This system feeds power into the main panel and any possible surplus into the main utility grid, where it is credited for future use. In our area, power used is balanced with power produced each January first -- once a net metering agreement is signed -- giving credit for power produced, up to the amount of your total bill. Systems up to 25 kW can qualify in Washington.

Below: Batteryless Grid-Tie Photovoltaic Systems

As Easy as -- 1) Install PV panels, run wiring to main panel 2) Install inverter next to main panel 3) Have your utility company install a dual direction meter!

(Well, ALMOST that simple! Granted, there are always details.............)

A growing number of builders are trying to begin to undo what is environmentally wrong with today's building methods and they are also integrating solar and renewable energy systems. AC BUILDERS of Edmonds, Washington is among them. With Sun/Wind's help they have implemented solar electricity. This home belongs to Armando Chilelli, the owner of AC BUILDERS and incorporates a 1200 Watt peak photovoltaic system -- ASE panels. The system is expandable. The inverter can accomodate up to another 1800 Watts of PV and Armando's roof will easily accomodate the future addition.

Seeing your PV panels produce electricity for the first time is exciting! Being able to convert sunshine to electic power is a miracle! It holds promise for our future survival as a species; for preserving life's diversity and improving the quality of life.

Above: An incandescent lamp is used to test the PV array. In this case, 68 to 85 Volts DC are providing the energy to light the lamp.

Below: Snohomish County Public Utility District installs a special digital meter which provides an accurate assessment for energy incoming and outgoing.

Not as difficult as it may seem! And, here in Puget Sound, we have an average of 3.5 to 3.8 hours of sun per day, averaged over the year. In eastern Washington and many other southern U.S. areas, the available sun ranges from 4.5 to 5.5 hours per day. PV panels can be mounted on the roof, in the yard at ground level with racks, or they can be mounted on poles to get them high in the air for maximum sun, away from possible vandalism and flying rocks from lawnmowers. Using ground mounts or pole mounts allows the PV panels to be placed in an area in the yard with maximum sun exposure. In this case, mounting on the roof was chosen. This can be accomplished with mounts connected to trusses or stringers.

A special problem in Port Angeles: How to obtain maximum solar exposure, as trees shaded much of this yard in the morning. And to the west, other trees shade the roof in the late hours of the day. Solution: Install a WattSun Tracker on a 25 foot tall 6" schedule 40 steel pipe and attach it securely to a reinforced truss in the garage! This accomplished 2 things: It allows the PV panels to be mounted high in the air and away from tree shadows and it also provides up to 25% additional yearly energy since the tracker automatically follows the sun during the day and also automatically compensates for winter/summer sun declination. This one kW array and SW5548 inverter prove that solar power is available and practical even in the rainforest areas of Western WA. Port Angeles gets about three hours of sun per day on the average over the year. The WattSun tracker stores the array in a horizontal position when it gets dark, thus protecting the array from possible night storm damage. Trackers can increase system output if you can mount the array(s) in an area that provides a wide solar window, i.e., early sunrise, late sunset. Sixteen L-16 deep cycle batteries insure that this home always has power. The system is grid-tied and net metered. Note that special building engineering is a necessity to properly support an elevated tracker. This mounting system and garage were inspected by the Port Angeles Building Inspection Department before the panels were mounted. The wind loads can be SIGNIFICANT!

If you only can achieve a limited solar window (less than 6 hours of sun in the summer) it makes better economic sense NOT to install a tracker, as today's PV panels provide a nearly uniform output 30 TO 40 degrees north, south, east and west of a line exactly perpendicular to the PV panels' surface (a line drawn between you and the sun). To understand this, hold a straight stick so that its length lines up with the sun. Do this at about noon or one o'clock. Now place a protractor over the stick with its 90 degree mark and its bottom center mark lined up exactly over a straight edge of the stick. The power received by the panel will deviate little within an arc between 50 and 130 degrees -- a total of 80 degrees of arc. If your sunrise begins at 30 degrees or less and ends at 150 degrees or more, a tracker can be beneficial if there are no other obstructions. A solar pathfinder survey will assess the solar potential for the site. This can be done even in cloudy weather since the pathfinder uses established solar data, geometry and mirrored reflections of surrounding objects, buildings and trees.

BATTERYLESS SYSTEMS and installation issues for all renewable energy systems

The Sun Tie system below (The new model is the GT Series) should be installed by an electrician. (We can furnish an electrician in local areas.) However, it is one of simplest types of grid-interactive systems and can be installed by the homeowner, if you are confident with your electrical and mechanical skills. The grid interactive inverter has all the U.S. National Electric Code required breakers built-in. The Maximum Power Point Tracking photovoltaic controller is also built-in! It needs no batteries! This is a grid-tied inverter that only produces power when the grid is live, therefore, it 'can't' back-feed the grid when the utility fails. This is called anti-islanding and protects utility workers when they are working on the utility distribution system. It meets the standards set forth by the Underwriters Laboratory. If you install it yourself, you must do so with your main house breakers turned off and it is highly recommended that an electrician inspect your work and connect the inspected system to your main service panel to be sure that it is correctly installed. Sun/Wind can provide one-line drawings and/or equipment schematics. We are also available on a consulting basis before, during and after installation. Sun/Wind carries the seven major brand names available for grid-tie systems. The Xantrex GT3 is currently the easiest to install, the most efficient, and the best value.

You will need a set of photovoltaic panels and will need to decide whether to mount them in your yard or on the roof. Many people are electing to mount the PV arrays in their yard on pole mounts to eliminate the possibility of leaks in the roof, and/or to place them in the most effective location to produce the maximum amount of energy possible. However, effective techniques are available to reduce the possibility of leakage should you need or prefer roof mounting.

PV mounting systems are becoming simpler and better every year. It is helpful to have an electrical contractor install your system and required unless you do the job and apply for the permit yourself. Sun Wind installers generally will perform the installation within a 150 mile radius. Our drawings and instruction manuals provide details for contractors and owner installers but we only recommend this if your electrical contractor is interested in installing solar. We do not recommend owner installations unless the owner is familiar with national electric codes and has adequate electrical experience.

Our 'Solar Path Finder' can help you greatly in finding the best mounting location and can calculate the amount of solar radiation available. There are other methods available if you choose to do it yourself, however, it would be beneficial to have this pathfinder reading and energy analysis for your proposed location. It is possible that you may have trees or other objects that may interfere with the sun's radiation (remember that the sun's declination changes from summer to winter and in our northern hemisphere the sun will be much lower in winter and much higher in the summer). It is also possible (and highly recommended) to reduce the cost of your system by evaluating and adjusting your current energy use, and selecting the best use of your electrical energy (see "Incentives and Secrets" page). The best location for PV panels has a sunny south facing exposure and is free from tree or building shadows between the hours of 9 am and 5 pm (or 10 and 6 if Daylight Time). Systems can be installed in areas with less solar radiation but the output of your system will be proportional. Consideration needs to be given to the sun's lower elevation in winter. Shadow areas should be avoided. The location with the best southern exposure and the least shadow interference will help to determine whether to select ground, roof, or pole mounts.

Roof mounting requires special attention to mounting studs to prevent roof leaks. Mounts and bolts should connect to rafters or cross braces. There are several methods, but preventing leaks is a prime requirement. The selection of proper frames for mounting PV panels is essential. Leak-proof roof jacks over a mounting stainless steel lag bolts and L feet can help, but it is essential that bolt holes be precisely sized and placed, and that the holes are filled with an appropriate roof sealer/caulk, which matches and adheres to the roofing material type. This must be also properly sealed to the roofing to prevent leaks and water penetration into the lag bolt holes. These must be properly and tightly bolted into the roof truss, rafter or cross brace. The roof jack is the same type as is used for vent pipes but is specifically designed for photovoltaic mounts. Mounting frames must be elevated a few inches to keep the panels cool (PV panels are more efficient when cooled.)

A high quality roofing sealant (or marine sealer in the case of a metal roof) can be applied to the lag bolts and holes to prevent leaks. Asphalt or tar based sealants should be used for asphalt or composition roofs. Stainless steel hardware with aluminum frames are prefered for high quality installation. We have a simplified Uni-Rac mounting system that greatly reduces install time and expense. We are always happy to provide installation or instruction and consultation. We provide a minimum free consultation time by phone, fax, email and U.S. mail with each system and can and go to installation sites for an appropriate reasonable fee.

Final approval is relinquished to state electrical inspectors and where applicable local building departments. Our electrical contractor will deal with the permit issues and inspections as well. Since the net metering agreement is between you and the utility, it will be necessary for you to obtain this agreement from them and get it filled out. We can assist you with this.

We can furnish you with drawings, specifications or designs, if required by your utility and inspection department. We can help guide you through the process. It seems complex -- but in actuality, in the vast majority of cases is not nearly as difficult as it may sound. It just takes a little time and patience and with this process comes the assurance that your system is properly and safely installed. After installation and after the system has been inspected by your electrical inspector and utility, it can be connected to the main panel and turned on.

See our page on "System Specials." We have many pre-engineered grid-tie models. We also can provide a system that is especially designed for your needs. The system below can be ordered in a a standard 1.2 kiloWatt, 1.7 kW, or 2.6kW PhotoVoltaic package. We do have considerable flexibility in design and can tailor a system to your needs.

Check with your state energy office to make sure you have a net metering law. Yes, we do in Washington, Oregon, California and most states!

The process of getting utility approval is required only for grid-tie systems that back-feed the grid and does not apply to automatic or manual transfer switched renewable energy systems (those that supply power to your home only and not to the grid). However, it is the law that ALL systems be properly inspected by an electrical inspector to avoid safety problems. Even for an off-grid home this it is possible for the installer to mis-wire it and cause equipment failure and even fire. Some grid connected people have mistakenly wired their gas or diesel generator sets to their main panels, only to blow up their generators or inverter. Renewable energy systems need to be properly connected and transfer switches need to be installed and tested.

We have battery-type utility co-existing systems to provide back-up power only, solar powered back-up and utility co-existing sytems, as well as totally independent systems. Some systems are not grid-tied but the loads can be switched from utility to battery -- automatically. We also have battery systems that operate as a grid-tie systems providing grid-tie with utility back up capability -- automatically!

Solar PV is actually is an "investment" as a system will increase the value of your home; reduce your electric bill; not depreciate (like an automobile); hedge against further utility increases; allow the owners to have control over their energy destiny their own energy policy; allow participation in reducing greenhouse emissions; reduce our reliance on foreign oil; set an example of environmental stewardship; serve as a model and example for others to follow and assist in teaching all those who see it!

Note: This system has now been replaced by even higher output panels and a more efficient inverter. Most of the performance criteria and methods still apply. See our "New Special Systems Offers" page.

Copyright October 10, 2004 Tom W. Rentz

CLEAN AND RELIABLE POWER FOR THE NEW MILLENNIUM!

POWER FROM NATURAL SOURCES -- NO FUEL EMISSIONS OR C02

NEW GENERATION SOLAR PV SYSTEMS, WIND & "HYBRID SYSTEMS"

SLOW DOWN YOUR ELECTRIC METER

ALL SIZES AND BUDGETS -- KITS AND PRE-DESIGNED SYSTEMS AVAILABLE

BE "YOUR OWN POWER COMPANY"

INDEPENDENT AND REMOTE POWER OPTIONS

Typical performance of a 1,500 Watt PV system

Batteryless Sine wave systems will feed power back into the grid without batteries. (For battery back-up power/independent systems we specify DR or SW models rather than a SunTie or grid-tie only model inverter). The beauty in the grid-tie system is that a battery bank is not needed since the system uses the utility grid for its battery bank. The Sun/Wind MILLENNIUM STAR SYSTEM simply feeds power directly to the grid, being consumed at you home or point of use first, thereby lessening the utility load.

This system is designed to reduce your electric bill. In the "lower 48 United States" our northern latitudes it will produce approximately 3.37 kW hours per day or approximately 100 kW hours per month in most rainy areas (rain forests may be lower, based on a 3.5 hour average sun per day -- Seattle). In the southern latitudes it will produce approximately 4.7 kW hours per day or 141 kW hours per month based on 5 hours per day average sunshine. (Estimates assume that the system is in full bright sun without shadows from trees. Obstructions will reduce the output. If you add an optional solar tracker, output can be increased by 20 to 25% annually. However, solar trackers add to the system cost and require extra work to install.

Take a look at your electric bill and determine your monthly kW hour average use, over a period of a year. This system has been rated in average kW hours produced per month. It will provide you with a portion of that monthly power requirement. Compare your consumption to that provided by the system to determine what you might save. Example: If you use 500 kW hours per month, then by divide 500 by 100 = 5. To convert this to percent divide 100 by 5 = 20% (approximate) or 20 % of your bill. Naturally, the larger the PV system, the more you will save on your electric bill. And, the more you use other sources (rather than electricity) to provide your heat, hot water, clothes drying and cook stove -- such as gas or solar thermal -- your overall electric load decreases and thus the cost of your system will be lower. If you implement an energy conservation plan (low power consumption appliances and lights, etc.), you can save additional energy and economically provide a larger percentage of your own power. Install 3 of these systems = the price of a luxury car and your benefits will last a lifetime rather than depreciated each year!) (Actual PV system kW hour output may vary according to weather patterns, obstructing trees or buildings. The solar insolation ((radiation)) figures are regional averages.)

The component breakdown is as follows:

10 Sharp or Shell 150 Watt Solar Panels (or equivalent)

Roof Mounts (yard mounts at extra cost)

Xantrex Sun Tie XR 1.5 kW Inverter

(battery-less, no back-up power)

Shipping and handling are extra.

For a single system the only other items that are required are a dual dedicated 15 Amp. circuit breaker in your main supply panel and wiring to the inverter from the panel (purchase from your local electrical outlet to match your panel). The PV panels must be connected per instructions and fastened the to your roof or yard mount racks. Optionally, you can have this installed or connected by your local electrician, or you can follow our instructions. We provide consultation.

Net metering laws are now in effect in 22 states. WA State has a net metering law. As required by law, utilities must give credit for the energy produced at the same rate that the user pays, up to the amount of your bill. An agreement must be signed after the system has been inspected.

In areas where there is concern over such an agreement or where net metering laws are not implemented or where an independent system is desired, install a modified or sine wave model inverter and battery bank. This allows the user to run his system independently, separate and apart from the utility.

Typical performance of a 2.4 kW system

Batteryless Sine wave systems will feed power back into the grid without batteries. (For battery back-up power/independent systems we specify DR or SW models rather than a SunTie or grid-tie only model inverter). The beauty in the grid-tie system is that a battery bank is not needed since the system uses the grid for its battery bank. The Sun/Wind MILLENNIUM STAR SYSTEM simply feeds power directly to the grid, being consumed at you home or point of use first, thereby lessening the utility load. These systems can even run your power meter backwards during sunny periods when there is no appreciable load.

This system is designed to reduce your electric bill. In the "lower 48 United States" our northern latitudes it will produce approximately 5.88 kW hours per day or 176.4 kW hours per month in most rainy areas (rain forests may be lower, based on a 3.5 hour average sun per day -- Seattle). If you add an optional solar tracker, output can be increased by 20 to 25% annually. Or you can install more panels to achieve a higher output if desired.

Take a look at your electric bill and determine your monthly kW hour average use, over a period of a year. This system has been rated in average kW hours produced per month and will provide you with a portion of that monthly power requirement. Compare your consumption to that provided by the system to determine what you might save. Example: If you use 500kW hours per month, then by dividing 500 by 176.4 you get 2.834. Convert this to a percent by dividing it into 100. The answer is 35.28%. (or divide by 252 kW hours in southern U.S. lattitudes = 4.8. 100/4.8 = 50%) Naturally, the larger the system, the more you will save on your electric bill. And, the more you use other sources (rather than electricity) to provide your heat and hot water -- such as gas or solar thermal, your overall electric load decreases. If you implement an energy conservation plan (low power consumption appliances and lights, etc.), you can save additional energy and economically provide a larger percentage of your own power. (You can purchase this system for the price of an economy car and it will continue to give you a lifetime return on your investment and not depreciate like an automobile!) Actual PV system kW hour output may vary according to weather patterns, obstructing trees or buildings. The solar insolation radiation -- figures are national averages.

The component breakdown is as follows:

2.4 kW (24 ea.) Sharp or Shell Power Panels

Roof Mounts (yard mounts at addtional cost)

2.5 kW Trace/Xantrex Sun-TieXR or SMA Sunny Boy 2500 w/display

(battery-less, no back up power)

In most systems the only other items that are required are a dedicated dual 15 Amp. circuit breaker in your main supply panel and wiring to the inverter from the panel (purchase from your local electrical outlet to match your panel). The PV panels must be connected per instructions and fastened the to your roof or yard mount racks. Optionally, you can have this installed or connected by your local electrician, or you can follow our instructions. We provide consultation.

Typical performance of a 4.8 kW PV system

Batteryless Sine wave systems will feed power back into the grid without batteries. (For battery back-up power/independent systems we specify DR or SW models rather than a SunTie or grid-tie only model inverter). The beauty in the grid-tie system is that a battery bank is not needed since the system uses the grid for its battery bank. The Sun/wind MILLENNIUM STAR SYSTEM simply feeds power directly to the grid, being consumed at you home or point of use first, thereby lessening the utility load.

(Actual PV system kW hour output may vary according to weather patterns, obstructing trees or buildings. Shipping and handling are additional. Most shipping is handled UPS. The output of these systems is approximately 11.7 kW hours per day at latitude 46 (Seattle) as compared to 16.8 kW hours per day at latitude 30 to 35 (southern U.S.) For northern latitudes this system can produce up to 70% of needed electrical power for a home that consumes 500 kW hours per month (up to 100% in southern U.S. latitudes).

For a low cost sytem recommendation and site survey see the page above: SYSTEMS AND SITE SURVEY FORM

Site surveys are available for $125 (plus ferry fees) for a 60 mile radius. These include a site and load evaluation as well as a preliminary system quote. We will and do designs and quotes all over Washington as well as other states.

Components, system prices and product availability are subject to change without notice. Once your order is acknowledged and accepted the price is then firm.

All contents of this web site are copyrighted except where specific pages are exempted. Copying, reproducing, reformatting or distribution by any means including photographic or electronic reproduction is prohibited, other than as per the guidelines provided: One printed copy for non-commercial 'personal use only' or copies for 'educational purposes' within a bonified educational institution is permitted. All other reproduction must be pre-approved in writing by Sun/Wind Concepts or Tom W. Rentz.

Copyright March 8, 2005 by

Tom W. Rentz/SunWind Concepts

Camano Island, Washington, USA