(This file is PVXLman.txt)


PVXL V2.0 MANUAL

WARNING!
PVXL is an "add in" template for Microsoft Excel 97.  It is not compatible with 
previous versions of MS Excel.


WHY READ THIS STUFF WHEN I CAN USE PVXL NOW?
Good question!  Some folks read instructions and some don't.  If you have already 
opened PVXL.xlt successfully and saved it as a workbook (.xls), then go for it!
You can't hurt a thing.  

PVXL is heavily populated with pop-up comments and checks to see if you have 
entered the "correct" data. In fact, if you get in a bind, you'll get an alert and you 
can always read the comments that pop up from the cells.  If you are familiar with 
PV design terms, start designing! Print this manual out and use it as a reference as 
you go along.


RECEIPE FOR SUCCESS
Arm yourself with information about your loads. Mix in solar insolation data and toss 
with a basic understanding of batteries and PV's. Now add a dash of you favorite 
components, a tad of common sense, and a pinch of prices. You'll whip up a PV 
system design faster than it takes bread to rise!


LOADS AND SUNSHINE CHANGE WITH THE SEASON
PVXL allows you to quickly change load duration and peak sun hours entries.
Consider running PVXL at least 4 times, December, March, June and September, if 
you have a year round application.


PRINTING PVXL
Each PVXL worksheet prints out in a clean report on 8.5 x 11.5 paper.  No 
"chopping" at mid-table. Try it and see.  However, Sheet 7: Specifications is an 
exception with the understanding that it is a database and will rarely be printed out.




OVERVIEW 
--------------------------------------------------------------------------------

THE WORKBOOK TEMPLATE
PVXL contains 7 worksheets enclosed within a single workbook.
There is a dedicated Excel worksheet for each the following:
- System Notes.
- Electric Loads.
- Battery Bank.
- PV Array.
- Balance of the System (BOS).
- Cost Analysis and System Summary.
- Specifications sheet for module and battery data.


PROTECTED CELLS
Every worksheet protects most cells to guarantee that you can only enter data in the 
proper fields.  Just use the TAB key to go from one input field to the next.  Tabbing 
allows you to skip from entry to entry.  By tabbing, you can quickly jump to all the data input 
fields. Or you may use your mouse to double click and enter data if you prefer.

DATA VALIDATION
Each input field, whether text or numeric, is validated.  The data validation assures 
that you make a proper entry.  For example, if a number is expected, and you type 
the letter "O" rather than a zero, an alert window pops up. The alert window contains 
information about what type of number or text length is desired.

COMMENTS
There are pop-up windows that contain comments.  Hover your cursor over any cell 
with a small red triangle in the upper right corner.  A comment window pops up with 
descriptive information and tips about the data entry or the output value displayed.


CALCULATIONS
The worksheets contain hidden and protected formulas.  Changes made in one 
worksheet will force calculations on some others. You can change any value on any 
sheet and it will update all the others that link to that data in one way or another.

For example, you have made a "first pass" and completed all the worksheets.
Perhaps you would like to change the system voltage from 24 volts to 12. Make the 
change on the Load worksheet and 4 other pages recalculate.  Similarly, any of your 
input values, battery, module, peak sun hours, can be changed and the appropriate 
calculations are made throughout the workbook.





CREATE A NEW PROJECT WORKBOOK
-------------------------------------------------------------------------------

NOTE: Install PVXL.xlt as described in the file PVXLins.txt.
OPEN MS Excel 97 and double click PVXL.xlt.
SAVE the new file as "yourname.xls"

SHEET 1: PV SYSTEM DESIGN NOTES _________________________

There are three fields to enter information about the Project, Date and Designer and 
two fields for Seasonal and Array data.  All five of these fields are automatically 
imported into the Cost Analysis worksheet.   Type something in, jump to the Cost 
Analysis and see.

The remaining large text box field is a place for your notes, etc.



SHEET 2: ELECTRIC LOADS ________________________________

FORMS
There are four forms in this worksheet.  DC Loads, 120 VAC Loads, 240 VAC Loads 
and a Load Summary Table.  


SET THE SYSTEM VOLTAGE
The DC System voltage, normally the voltage of the battery bank, is set in the very 
first field in the DC Loads Form.  The default is set to 24 VDC and you can change it 
to any value.

The DC system voltage is carried forward into the Battery Bank, PV Array and Cost 
Analysis sheets.  The Load Sheet is the place to set and make any changes to the DC System 
Voltage.  You can change this value at any time.  Make sure that the battery bank 
single cell voltage is evenly divisible into the system voltage, otherwise you will 
"flag" an error. IE: Your system voltage is 12 VDC and you select a 8 VDC cell will 
generate an error. Select a 2, 4, 6 or 12 VDC cell instead.

DC, 120 VAC and 240 VAC LOAD FORMS
Load name - Text entry: A light, TV, pump or?
Qty: Whole number - How many identical loads are there, 1, 3 or?
Watts: Whole number - What is the wattage rating of the load? 
Hours: Decimal accepted - Average hours per day that the load is "on."
Watt Hrs: Power consumption is automatically calculated. Qty x Watts x Hrs = W hrs.

Hover your cursor over the red comment marker and view the notes.
TAB through each field and add your loads.  If you type something incorrect, or out 
of range, you'll get an alert.  You can't "hurt" the worksheets, so feel free to 
experiment!  If your loads don't fill out a form, just TAB to the next form.  Don't 
bother to put anything in unused or "blank" load fields.  

The following four values are calculated for each Load Form
Total Watt Hours - Sum of all load watt hrs.
Total Connected Watts - Sum of the wattage's of the connected loads.
Peak DC Amp Draw - Total Connected Watts divided by the DC system voltage.
Total DC Amp Hours - Total Watt Hours divided by the DC system voltage.


ELECTRIC LOAD SUMMARY TABLE
Is calculated and displayed.  It shows the Total Watt Hours, Total Connected Watts, 
Peak DC Amp Draw and Total DC Amp Hours, for each type of load and then shows 
the system total.

The Total DC Amp Hours is forwarded to the Battery Banks worksheet.

CHANGING VALUES
You may change any value that you have entered at any time.  The change is 
reflected through the workbook.



SHEET 3: BATTERY BANK ________________________________

FORMS
There are two forms: INPUT and OUTPUT.


BATTERY BANK INPUTS

--- Battery Selection ---
You need to select a battery by scrolling the list in the battery menu.  Click on a 
battery description and five fields are filled out automatically.  The 5 fields are: 
Manufacturer, Model, Discharge Rate, Nominal (single cell) voltage, and Amp Hour 
Capacity.  There are 130 battery models in the list with room to add your own 
selections.  See Sheet 7: Specifications, for making additions or changes to 
batteries.

--- Battery Bank Requirements ---
Both the Daily Amp Hour Load and the DC System Voltage are imported from Sheet 
2: Loads.  If you want to change the values, make them in the Load Sheet.

Depth of Discharge of the battery bank - The default is 0.35 or 35%. If you set the 
DOD to 100% (1.0), you are allowing for total depletion of the battery bank.  Not a 
good idea! 80% (0.80) is the recommended, absolute maximum. 

NOTE: Excel gets a bit sneaky here.  Replace the digits with a new numeric value, leave 
the % character and you are fine.  If you erase the % character, then you'll have to 
enter a decimal value (.35 is automatically converted to 35%).  Not to worry, you'll 
get an alert if you have an entry out of range.

Days of Storage - Default is set to 3 days.  Without any charging from the PV array, 
haw many consecutive days will the battery bank supply power to the given DOD? 
Change this number and watch the results in the total number of batteries.

Battery Chemistry Efficiency - Default is 85%. Batteries store electric energy in a 
chemical form.  They are not 100% efficient, even when brand new.  Older batteries 
have lower efficiencies.  Consult your Manufacturer for details. If there is a loss, then 
the Amp Hour Load will be "adjusted" upward.

Battery Temperature Derate - Default is 0%, (none). At room temperature the 
batteries a rated a 100% capacity.  Below freezing 32F (0C), most batteries will 
show a reduction in capacity. At extremely low temperatures, the batteries can have 
a 50% reduction in capacity.  The capacity is restored when the batteries are 
warmed up.

Consider what happens to your car battery during a severe winter night.  You might 
get a "dead" battery.  Warm it up and it has full capacity again.  Consult your 
Manufacturer for Capacity vs. Temperature data if your battery bank is subjected to 
extreme temperatures. If there is a loss, then the Amp Hour Load is "adjusted" 
upward.

PV Controller Efficiency - Default set to 99% efficient. Account for any charging 
power loss through the controller.  If there is a loss, then the Amp Hour Load is 
"adjusted" upward.

System Wire Loss - Default set to 98% efficient.  Account for power loss from the 
charging and discharging system. If there is a loss, then the Amp Hour Load is 
"adjusted" upward.

Inverter Efficiency - Default set to 90%.  Account for DC to AC power conversion 
losses.  Set to 100% if there is no inverter.  Inverter efficiency changes as the AC 
demand changes.  

Every inverter has a "power curve."  Consult your manufacturer 
for details. If there is a loss, then the Amp Hour Load is "adjusted" upward.


BATTERY BANK OUTPUTS

--- Amp Hour Adjustments ---
Power Loss - Is the result of all the power loss factors.

Adjusted Daily Amp Hours - The increase in the Amp Hour Load due to the power 
losses.  Mathematically it is: Adj. AH = Daily Amp hr load divided by (1 minus Power 
Loss).

--- Battery Bank: Amp Hour data ---
Cycled Amp Hours - Adjusted Daily Amp Hours multiplied by Days of Storage. The  
battery capacity that is allowed to be discharged.

Actual AH Capacity - The total capacity of the battery bank using the battery you 
selected.

Target AH Capacity - The total capacity of an "optimum" battery bank.  The size of a 
bank that meets precisely meets your needs.

AH Capacity from Target - The AH difference between Actual AH Capacity and Target 
AH Capacity.

NOTE: PVXL automatically calculates a battery bank size such that the Actual AH 
Capacity equals or exceeds the Target AH Capacity.  Want a smaller bank? You'll see, 
in a moment, how to change the battery bank size with a click of the mouse.

Actual Depth of Discharge - Cycled AH divided by the Actual AH Capacity.  How close 
is it to your desired DOD?  The Days of storage mirror your original selection.

--- Battery Bank Configuration  ---

Suggested Parallel - PVXL calculates and suggests the minimum parallel strings of 
batteries to satisfy your requirements.

Total Number of Batteries - Batteries in Series multiplied by number of Parallel 
Strings.

Batteries in Series - DC System Voltage divided by the nominal voltage of a single 
battery.

Parallel Strings - The number of series strings in the battery bank.

Change Parallel - Here is where the fun begins.  Click the up arrow and increase the 
parallel number.  Notice how the figures change.  Click the down arrow and decrease 
the parallel number.  It won't allow you to go to zero and it replaces the zero value 
to where you started, at the Suggested Parallel number.

TIPS!
Scroll up and change the battery model in the battery selection menu.  Feel free to 
experiment.  Run through some different batteries.  Change the days of storage and 
the depth of discharge.  See what happens if the battery chemical efficiency drops. 
Pretend that your batteries are extremely cold.  Set to temperature derate to 40% 
and watch the huge increase in the battery bank size.

If you want to change the system voltage, click over to the Load Sheet and change 
the value at the top of the DC Form.  You can always save the document now, then 
SAVE AS another name and "play" with PVXL.  You can always pull up your saved 
work later and continue on your way.

Take a peek forward at the Cost Analysis Sheet.  See what is already entered for you 
automatically.  Enter a price for the appropriate battery and your battery bank cost 
is calculated.  OK, enough digressing, time to move on to the PV Array.


SHEET 4: PV ARRAY ________________________________


FORMS
There are two forms INPUT and OUTPUT.



PV ARRAY INPUTS
--- PV Module Selection ---
You may select a module by scrolling the list in module menu.  Click on the module 
description and eight fields are filled out automatically.  The 8 fields are: 
Manufacturer, Model, Nominal Module Voltage, Nominal Wattage Rating, Rated 
Current, Rated Voltage, Short Circuit Current and Open Circuit Voltage.  There are 
over 36 module models in the list with room to add your own selections.  See Sheet 
7: Specifications, for making additions or changes to modules.

--- PV System Requirements ---
Adjusted Daily AH Load - Is imported from Sheet 3: Battery Bank worksheet.

DC System Voltage - Is imported from Sheet 2: Loads worksheet.

Peak Sun Hours - For your location, season and array tilt and mount type, how much 
sun strikes the surface of the PV array? Peak Sun Hours are measured in 
KWH/square meter.  

This value is not automatically calculated or entered.  You must 
supply this number of Peak Sun Hours. But the data is very easy to get.  

There are at least five sources listed in my web site at 
http://solarmike.interspeed.net/. If you are a consumer, and you are testing a 
design given to you by a PV system supplier, ask the designer what peak sun 
value(s) they use.

Target Solar to Load Ratio - Default set to 100% (1.0).  What amount of the daily 
load should the PV's supply?  Perhaps, 100% in the summer and 75% in the winter?  
Suppose you have wind power or small hydro too?  Then you don't need solar to 
provide 100% of the load at all times.  

NOTE: Adjusting the Target Solar to Load Ratio allows you to scale back the solar 
input for a number of valid reasons.  This single factor is a major strength of PVXL 
and the lack of it is where many $100 PV design programs fail. 

Temperature Power Loss - Default is set to 0% (none).  As module operating rise, 
the module voltage drops proportionally.  Always review the Manufacturers module 
data for the voltage drop vs. temperature curves.  This is where some designers "cut 
corners" and "shade" the truth.

Other Module Power Loss - Default is set to 0% (none).  Dust, grime and pollution 
can obscure a module.  Take a look at the windows in your home.  Deduct 5% for 
dirty modules if you don't get much rain. Similarly, snow and frost can build up on 
modules. Scrape your car windshield in the winter? Consider deducting 2% for winter 
moisture.

NOTE: Are you considering purchasing "used" or "recycled" modules?  Are they "sun 
burned" a bit?  A deduction of 10% or more is fair for ten-year-old modules. Make 
sure the seller has tested some and compared them to the original specifications.



PV ARRAY OUTPUTS
--- Array Current Adjustment ---
Array Design Current - Is the Adjusted Daily AH Load divided by the Peak Sun Hours.

Array Power Loss - The result of the Temperature Power Loss multiplied by Other 
Module Power Loss.

Adjusted Design Current - Increase in the Array Design Current due to module power 
loss.  Mathematically equal to Array Design Current divided by (1 - Array Power 
Loss).

--- PV Array: System Data ---
Array Operating Current - Parallel module strings multiplied by the Normal Operating 
Current of a single module.

Array Operating Voltage - Number of modules in series multiplied by the Normal 
Operating Voltage of a single module.

Short Circuit Current - Parallel module strings multiplied by the Short Circuit Current 
of a single module.
 
Open Circuit Voltage - Number of modules in series multiplied by the Open Circuit 
Voltage of a single module.

Actual Array Amp Hours - Amp Hours produced by the array.

Actual Solar to Load Ratio - The percentage of the load supplied by the array. 

Target Array Amp Hours - The "optimum" Amp Hour production of an array that just 
satisfies the load.

Array Amp Hours from Target - The difference between the Target Array Amp Hours 
and the Actual Array Amp Hours.

--- PV Array Configuration ---
Suggested Parallel - PVXL calculates and suggests the minimum parallel strings of 
modules to satisfy your requirements.

Total Number of modules - Modules in Series multiplied by number of Parallel 
Strings.

Modules in Series - DC System Voltage divided by the nominal voltage of a single 
module.

Parallel Strings - The number of series strings in the PV array.

Change Parallel - More fun!  Click the up arrow and increase the parallel number.  
Notice how the module figures change.  Click the down arrow and decrease the 
parallel number.  It won't allow you to go to zero and it replaces the zero value to 
where you started, at the Suggested Parallel number.

NOTE: Some modules can be configured in dual voltages.  IE: Either 12 or 24 volt.
You can change the data or add a new module configuration within Worksheet 7: 
Specifications.  More about that later.


TIPS!
Scroll up and change the module model in the module selection menu. Run through 
some different modules. 

If you want to change the system voltage, click over to the Load Sheet and change 
the value at the top of the DC Form.  Remember, that changing the system voltage 
now will make a quite a difference in the battery bank outputs. Try it and see.

You can always save the document now, then SAVE AS another name and "play" 
with PVXL.  You can always pull up your saved work later and continue forward.

Take a peek forward (again) at the Cost Analysis Sheet.  Notice what is already 
entered for you automatically.  Enter a price for the appropriate module and your PV 
array cost is calculated.




SHEET 5: BALANCE OF THE SYSTEM (BOS) ____________________________

FORMS
There are seven items in the top form.  Each item allows you to enter a description, 
quantity and a unit cost.  The seven items are: Inverter, Power Center (or PV 
controller), Module Mount, Battery Enclosure, System Wiring, Misc.1 and Misc. 2.

Each item is carried forward to the Cost Analysis worksheet.

The large text box form is for your notes and not reproduced elsewhere. 



SHEET 6: COST ANALYSIS  _____________________________________

FORMS
The is a Cost Analysis Form and a Quick System Summary Form

--- Cost Analysis ---
If you have completed Worksheets 1 through 5 than most of the fields should be 
filled out for you.

The Project, Date, Designer, Seasonal and Array Data are imported from the System 
Notes worksheet.

The Battery Data is provided from the Battery Bank worksheet.  Add in a "per 
battery" price and continue to the interconnects.  The proper number of 
interconnects is calculated, Just enter a price and a note about the wire size.

Similarly, the Module Data is provided from the Module Bank worksheet.  Add in a 
"per module" price and continue to the interconnects.  The proper number of 
interconnects is calculated, Just enter a price and a note about the wire size.

Any of the information from the Balance of the System is already calculated.

A TOTAL appears in the box at the bottom and is the sum of all the item totals 
above.  You can change unit cost and watch the TOTAL change. 

---- PV System: Quick Summary Table ---
Is a compilation of the most important data from the various worksheets.  Take note 
of the power losses and compare them to the Electric Load power consumption.

TIPS!
You can go back and adjust some loads. Add in another or remove one.
Perhaps you want to try a different battery, adjust the Depth of Discharge or the 
Days of Storage.  You can make similar changes in the module worksheet.  If the 
system price is to high, reduce the number of modules.  Try different strategies for 
reducing cost.

NOTE: If you change the model of the battery or module, make sure to change your 
price in the Cost Analysis form!





SHEET 7: SPECIFICATIONS  _____________________________________

EDIT THE GREEN CELLS ONLY!
Review the module and battery data within the GREEN cells.  You may edit them as 
you would normally in EXCEL 97.  You can cut, copy and paste.  You can edit within 
cells by double clicking.  Tab to the next cell when you are finished.

Please follow the cell formats because there is very little cell validation in the green 
cells. There is plenty of room at the bottom of each table for new modules or 
batteries.  You can test your changes by viewing the menu boxes on the page.

There are menu boxes and field value boxes to the right of the data tables.  You can 
use them to scroll through the tables and verify the data values.  Do not edit the 
menu box or the red data fields.

Make sure to save your changes!  Editing a workbook (.xls) does not mean that the 
template!  Edit the template (PVXL.xlt) directly to permanently alter the database.


END OF MANUAL


-----------------------
September 27, 1998
Michael Reed
solarmike@earthlink.net
http://solarmike.interspeed.net/

































