SOLAR SIZE V1.1 A Solar Photovoltaic System Design Aid for Windows by Keith Wamsley Copyright 1993 by Keith Wamsley All Rights Reserved Software Agreement This program is distributed as Shareware it is not Free Software. It is not public domain. It is copyrighted. You are granted permission to use Solar Size for a trial period of 30 days. After that time you must register to continue use. Registration is a mere $20.00 so please do so. A form is provided at the end of this document. I would also appreciate any comments you might have or if you find any bugs. If used, you will get a free upgrade. You are given permission and encouraged to copy and distribute this software if: 1) All files are included in the distribution, 2) No modification of any kind is made to any of the files, and 3) No fee is charged for the software. Keith Wamsley hereby disclaims all warranties relating to this software, whether expressed or implied, including without limitation any implied warranties of merchantability or fitness for a particular purpose. Keith Wamsley will not be liable for any special, incidental, consequential, indirect or similar damages from the use of this program. The person using the software bears all risk as to the quality and performance of the software. Windows, Visual Basic, and VBRun200.DLL are trademarks and copyrighted by Microsoft Corp. Table Of Contents TOPIC PAGE SECTION 1 - GENERAL INTRODUCTION 2 SYSTEM REQUIREMENTS 2 INSTALLATION 2 SECTION 2 - THE MAIN FORM 3 FORM INPUTS 3 FORM OUTPUTS 4 FORM OPTIONS 5 FILE MENU 6 OPTIONS - GENERAL 6 HELP MENU 7 SECTION 3 - LOAD CALCULATION FORM 8 FORM INPUTS 8 FORM OUTPUTS 9 SECTION 4 - HYDROGEN EVOLUTION FORM 10 SECTION 5 - OTHER 11 CALCULATION BASIS 11 BATTERY TYPE 11 ADVERTISEMENT 12 REGISTRATION 13 Page 1 SECTION 1 - GENERAL INTRODUCTION: This program will calculate the required battery size, solar array size, and array angle for installations requiring a solar power solution. It has the power and flexibility to adapt to your particular design needs. Solar Size has built in sun intensity and temperature data to ensure a reliable, properly designed installation. SYSTEM REQUIREMENTS This program will run on any system that is running Microsoft Windows Version 3.x. INSTALLATION There are six files you should have to run the program: SOLAR.EXE The main program SOLAR.INI Holds your configuration options MAJORUS.CDF Data file of major US cities SOLAR.LDF Winter peak sun hours data file USERDOC.TXT This file, User Documentation VBRUN200.DLL DLL file for Visual Basic Copy VBRUN200.DLL to your \Windows\System directory. If you already have this file you do not need to copy it again. The remaining files should be copied to the directory of your choice. They must all be in the same directory. To install in a Program Manager group: Select the group where you want the program to reside. Select "File" from the Program Manager menu bar then select "New". Select "Program Item". Select "OK". The Program Item Properties box will now open. On the Description text box, type "Solar Size". On the Command Line text box, type in the path you copied the files to and add Solar.Exe This line should look something like: C:\Solar\Solar.Exe if you used a directory named "Solar" when you copied the files. Page 2 SECTION 2 - THE MAIN FORM This is the primary form you will use to interface to the program. It can accept your input data and present your project's requirements back to you. All other forms are enhancements and options to assist your use of the program. This form will automatically appear whenever you start the program. FORM INPUTS LOAD IN AMPS: Enter the total load amps that the system will provide to all loads at nominal system voltage. Use an average value for all periodic loads. Example: A load is composed of two components: a 0.25 amp continuous load and a 2.1 amp radio that is on 2 minutes every 30 minutes. The Load Amps value to use is: 0.25 + 2.1 * 2 / 30 = 0.39 Amps You can let the program calculate this load for you by checking the "Calculate Load" box and filling in the load profile data on the "Load Calculation" form. See the Load Calculation form section for more details. HOURS / DAY LOAD IS SUPPLIED Enter the hours per day that the load above is powered by the system. Usually this is 24 hours except for lighting or navigational aids type of loads. This value times the Load in Amps must equal the total system amp-hour load in a 24 hour period. This data is supplied for you if the "Calculate Load" box is checked. MIN OPERATING TEMP DEG F Enter the lowest winter design temperature that the battery will be exposed to. Battery capacity diminishes with temperature. This value is used to calculate the battery capacity required at the worst conditions. Use good judgement; use of a 100 year spot low is unrealistic and will result in a high battery cost. The temperature used should be sustained for several hours. If you use a short backup time then you should be more conservative (use a lower Temperature) than if you use a long backup time. The City Data File option can supply this value for you. See the Options section for more information. Page 3 DAYS OF BACKUP REQUIRED How many days of battery backup do you require? This assumes that the battery is providing all electrical energy to the load. A minimum of five days is recommended. You should consider weather, critical nature of the load, proximity of maintenance personnel, etc., in determining this value. WINTER PEAK SUN HOURS The average number of hours in the winter that the solar panel is providing it's full output. Be sure not to use annual average sun hours. The program can determine this value for you if you know the site latitude and longitude. See the Options section for more information. BATTERY TYPE Batteries vary in recharge efficiencies and low temperature capacity changes. Hence the program must know the type of battery you are using. Most Gell Cells are the same as the Lead Calcium type. CALCULATE This tells the program to calculate the results based on your input values. MAIN FORM OUTPUTS These are the values that the program calculates for you based on your inputs. Use these values to chose your preferred vendors equipment. The outputs are located on the lower part of the main form. BATTERY TEMPERATURE CAPACITY This is the resulting battery capacity at the design winter temperature conditions at the site. It is expressed as a percentage of the batteries 77 degree F capacity. This value is used in the calculation for the required battery size to ensure the specified backup time in the winter. It is displayed as information to show the temperature effect on the battery. REQUIRED BATTERY SIZE This is the battery's required Amp - Hour rating at 77 Deg F you will need. Chose a battery or multiple batteries to obtain this capacity. Solar applications are characterized by a slow drain, therefore use the battery manufactures' long term (usually 24 hour) capacity rating. Chose a battery designed for Solar applications. This application is not typical of engine starting or float charged stationary battery systems. The solar battery is guaranteed to discharge every 24 hours. Proper battery type selection will ensure longer life and better performance. Page 4 ARRAY PEAK CHARGING CURRENT Chose an array or multiple arrays that can deliver this amperage at normal sun intensity. Be sure the system matches your required system voltage. This value should be considered the minimum array rating for a system. If the array will be partially shaded, coated, not orientated due south, or otherwise impaired; the required rating may need to be increased. Areas prone to long periods of cloudyness may also need additional capacity. PANEL ANGLE TO HORIZONTAL This is the angle the array should be mounted. This will permit optimal sun collection in the winter when the sun is lowest in the sky. The more north you are the higher the required angle. The array should be pointed due south. DESIGN OPTIONS - Main Form There are two main options available over and above the basic form entry methods. These methods assist the user in obtaining the winter peak sun hours and the minimum temperature for the site. CALCULATE SUN HOURS You may chose to let the program calculate the peak sun hours based on the site's longitude and latitude. This option is activated by clicking on the "calculate" option button in the Select Sun Hour Entry Method box. Once chosen, enter the sites longitude and latitude, then press the "Calc Sun Hours" button. The sun hours will be placed in the Winter Peak Sun Hours text box. You may switch back to a manual entry at any time by clicking the "User Input" option button. Most all good road maps have the Longitude and Latitude printed on them. Look hard at the map edges, as it is usually in small print. The Rand McNally Road Atlas shows this data. CITY SELECTION The city selection box allows you to pick from a list of cities and the program will determine the minimum temperature, latitude, and longitude values to use. You may chose to allow this feature to determine the temperature only, location only (latitude and longitude), or both by selecting the appropriate option button in City Selection Box. Page 5 The City Selection option also supports multiple lists. You may develop regional or special purpose lists. A list is loaded by selecting "Change City File" under the Options menu. The city data files are ordinary text files with a .CDF extension. You may use any text editor (like Windows NotePad) to create or modify the lists. FILE MENU The file menu allows you to save and recall all the data on a specific site. The default extension is .SDF for Site Data File. NEW Clears all text boxes in the form. OPEN Recalls a file from disk and places the data on the form. Any existing data on the form is overwritten. SAVE Saves all form data in the current file. The current file is shown on the end of the title block. If there is no current file then the program defaults to the Save As function. SAVE AS Allows you to save all form data under any file name in any directory. You would use this option to save a new sites data to a new file. This file name becomes the current file. PRINT The print option will give you a print out of all site data inputs and calculated outputs. Execution of this option calls another form that allows the input of company name, site location, project name, and project number. The print out will automatically print the current date. If you used the city selection option, the chosen city will show in the site location text box. You may change the entry to anything you wish without effecting the calculation. You may also chose to print the load profile data from the Load Calculation form and/or the Hydrogen Evolution data. OPTIONS MENU BATTERY END OF LIFE FACTOR Batteries gradually lose capacity throughout their life. Usually a battery's useful life is over when its' capacity falls below 80%. The program has a default value of 1.1 to compensate for this effect. The battery capacity is multiplied by this factor to determine required battery amp-hour capacity. You may change it to any value between 1.0 and 2.0. Page 6 SAVE CONFIGURATION This features saves your current options so they are automatically used the next time the program is started. The options saved are: 1. Sun Hour Entry Method 2. City Selection data preference 3. City Selection City file 4. Battery end of life factor 5. Battery Type Selections active at the time of execution of this option are saved. HELP MENU The help menu item provides you with an on line help. Click on any item you wish more information on. Help is also context sensitive, simply press the "F1" key and the help screen for the in focus control will appear. There is a help menu for the Main Form, Load Calculation Form, and Hydrogen Evolution Form. Page 7 SECTION 3 - LOAD CALCULATION FORM This form will calculate the equivalent amp and time required by the main form. You can enter up to eight individual loads of varying characteristics. It is not necessary to use this form, but it does provide a simple method for multiload applications. You may directly enter the data on the Main Form when the "Calculate Load" box is not checked. FORM INPUTS LOAD IN AMPS Enter the load current for each load in amps. Make sure you are using the load that the battery will see, not the output of a DC to DC converter for example. TIME ON Enter the time the load is drawing current ("ON") for each cycle. The value goes in the text box on the left. The time units are selected from the list box. One entry in the list box - "Cont." stands for continuous. Select this if the load is on continuously. All other time data for that load is filled in automatically if this selection is made. CYCLE PERIOD The cycle period is the time the load is in one turned on and off cycle. This cycle may or may not repeat, that is determined by the Time Active values. Example: A navigation flashing light is turned on for 5 seconds then is off for 10 seconds. The Time On is 5 Sec, the Cycle Period is 15 Sec. TIME ACTIVE This is the total time in one day that the load is active, either cycling or continuous. Another way of looking at this is that this value is equal to the number of On - Off cycles per day times the cycle period. In the above example if the light is turned on only at night the Time Active might be 14 Hours. For a continuous load this would be 24 Hours. The value here is per day so values greater than 24 Hours are not allowed. The following relationship must be true for valid time entry: Time On < or = Cycle Period < or = Time Active < or = 24 Hours Page 8 FORM OUTPUTS EQUIVALENT AMPS This is the average current for your loads that flows for the equivalent time. In other words: if all your loads were replaced by a single load that draws constant power for the equivalent time, this would be it's current draw. If the "Calculate Load" box is checked on the main form, this value is placed in the "Load in Amps" entry box on the main form. EQUIVALENT TIME This time is simply the longest time specified in the "Time Active" column. It becomes the basis for calculating the Equivalent Amps. If the "Calculate Load" box is checked on the main form, this value is placed in the "Hours / Day Load is Supplied" entry box on the main form. COMMANDS BUTTONS: CALCULATE AND CANCEL Both Outputs are calculated only when the "Calculate" button is pressed. Pressing "Cancel" does not result in any calculation but simply returns you to the Main Form. You may press "Cancel" after pressing "Calculate" as a quick way to return to the Main Form. The "Calculate Load" check box does not have to be checked to perform this calculation. If not checked the calculated values will be calculated and shown on the Load Calculation Form but the "Load in Amps" and "Hours / Day Load is Supplied" boxes on the Main Form will not be changed. The values shown on the Main Form are the ones used in the final Solar Array and Battery calculations. Page 9 SECTION 4 - HYDROGEN EVOLUTION WINDOW The act of charging a battery results in the release of Hydrogen gas. Hydrogen is a very light flammable gas (remember the Hindenburg?). Usually in Solar applications the amount of gas generated is so small that natural ventilation will keep the gas below it's lower flammable limit. The calculation here is the worst case calculation. This occurs when the battery is fully charged; when the battery is accepting a charge the amount of hydrogen released is much less. FORM INPUTS CHARGE CURRENT This is the current in amps that goes to the battery. If the full rated output of the solar array can go to the battery, use that value. The type of charger, your load, and array rating will determine the actual net current going to the battery. If a conventional battery charger was used, the "float" charge current value would be used. As an approximation, the program places the calculated peak required array current in this box for you. You must substitute a value that represents your final design actual to obtain an accurate calculation. This would be the float charge rating or Array rating minus load current if a shunt type or no regulator is used. NUMBER OF CELLS This is the number of cells that make up the battery. Usually counting the number of water filling caps is equal to the number of cells. Lead acid batteries require one cell for every 2 volts of system voltage. This would be 6 cells for a 12 volt system. NiCads require one cell for every 1.2 volts of system voltage. FORM OUTPUTS HYDROGEN EVOLUTION This is the amount of hydrogen produced in cubic feet per hour in a fully charged battery at your input conditions. Hydrogen is a flammable gas and caution must be exercised. See comments above. FRESH AIR TO DILUTE This is the amount of fresh air from ventilation that is required to keep the hydrogen from becoming a flammable concentration. This amount of air keeps the mixture too "lean" to burn. Note that this air make up rate will keep the ventilated area safe but the area immediately around the battery may have a flammable concentration. Care must be taken to keep ignition sources away from the battery. Hydrogen is much lighter than air and diffuses rapidly. Ventilation should be provided in the higher regions of the building to prevent trapping of hydrogen gas. Most Solar applications result in very small amounts of hydrogen generation. Usually natural building infiltration will provide adequate ventilation. Page 10 SECTION 5 CALCULATION BASIS There are three calculations performed once all the data is entered and Calculate is pressed. Solar Array Size The array is sized so that during the winter peak sun hours all the energy taken from the battery during "dark" hours is replaced plus fully powering the load. Batteries have a recharge efficiency; that is only a portion of the energy delivered to a battery is stored. This factor is taken into account. Naturally there are very few average winter days. Hence on some days the battery will not be fully recharged. There should be enough above average days to recover from the very cloudy ones. The number of battery backup days is the safety against long periods of cloudy days. That is why 5 is the recommended minimum. Battery Size The battery size is calculated by multiplying five factors: Load current, Hours/Day the load is supplied, days of backup desired, temperature derate, and end of life factor. Array Angle An easy one. This is latitude plus 15 degrees. The array face should be oriented due south to maximize winter performance. Minimum Temperature In additions to the calculations, you may be interested in where the minimum temperatures in the city data file comes from. The source is the ASHRAE 1985 Fundamentals Handbook. The numbers used are the 99% values. Simply stated: during the months of December, January, and February the listed temperature should be equaled or exceeded 99% of the time based on historical records. BATTERY TYPE Designers often ask what type of battery should I use? Everyone seems to have their favorite. Unfortunately there is no easy answer...it depends. Here are some factors to keep in mind: NiCads lose less capacity in colder temperatures than lead-acids, but have a lower recharge efficiency. Hence you may be able to use a smaller battery but have to use a larger solar array. NiCads have a longer life but cost more than lead-acids. Page 11 Among the lead-acids, the Lead Calcium is the usual winner. This battery uses very little water and is widely available for solar applications. ALWAYS be sure to use a battery designed for solar applications. An automotive battery from K Mart will not give satisfactory performance. INSTALLATION CONSIDERATIONS All electrical installations must be installed utilizing good engineering practices. This includes compliance with the National Electric Code. Article 690 specifically covers Solar Photovoltaic Systems. Article 480 (Storage Batteries) and 250 (Grounding) are also revelant. Since most solar power installation tend to be remote, pay particular attention to all details that will promote reliability. This includes: isolating the battery from temperature extremes, preventing corrosion, protection of wiring and terminations, location of the solar panel (shading, coating, etc.), and accessibility for maintenance. ADVERTISEMENT Shareware is a distribution method, not a type of software. You get to tryout the software before you pay for it. Load it up and run it like crazy for 30 days. If you don't like it, delete it from your machine. If you do like it, register it. Pass it on to anyone who might have an interest in it. Please distribute all files in the distribution set. Registration encourages further development and makes me a couple of bucks. There is an amazing amount of development time that went into this program. Registration for you eliminates the registration message, and allows us to notify you of any upgrades. It should also give you a warm glowing feeling of using legitimate software. Do you have special requirements or customization needs? Let me know, we can probably work something out. Any comments or suggestions would be greatly appreciated. You may reach me by mail at the address on the registration form or on Compuserve at 72427,400. Page 12 REGISTRATION: To register send your $20 to: Keith Wamsley 3403 Ft. Richmond Dr. Richmond, Tx. 77469 Please provide your: Name: ________________________________________________ Company: ________________________________________________ Street: ________________________________________________ City: ___________________________________ State: ______________________ Zip: ______________________ Version: ______________________ Serial Number: __________________________ (from About Menu) Comments: Thanks for your support!!