Grid-Tie Design
 Available at Solar Taos 2010 Product Catalog
 
 
UTILITY INTER-TIE (GRID-TIE) PV SYSTEM DESIGN

Budget, roof dimensions and other site-specific factors often call for custom system design. If you are planning to mount your array on a roof, decide which module best fits into the available roof space, taking into consideration obstructions such as chimneys, plumbing vents and skylights. See solar module section for dimensions of modules. A grid-connected PV system consists of PV modules, output cables, module mounting structures, AC and DC disconnect switches, inverter(s), grounding equipment and metering system.

The Worksheet below will help you decide what size PV array would be required to eliminate your electric bill. This will be the largest system that would be cost effective to install. A smaller system can reduce part of your bill, or eliminate higher cost electricity in locations that have progressively increasing rates as consumption increases. Use this information and the amount of available space to get a rough idea of your PV array size.

TO DETERMINE THE PV ARRAY SIZE FOR A GRID CONNECTED SYSTEM

Information Required

Fill in Amounts
Step 1 FIND YOUR MONTHLY AVERAGE ELECTRICITY USEAGE FROM YOUR ELECTRIC BILL  

This will be in kilowatt-hours (kWh). Due to air conditioning, heating and other seasonal usage, it is a good idea to look at several bills. You can add the typical summer, fall, winter and spring bills and divide by four to find the average monthly usage.
Step 2 FIND YOUR DAILY AVERAGE ELECTRICITY USE  

Divide the monthly average number of kWh use by 30 (days).
Step 3 FIND YOUR LOCATION’S AVERAGE PEAK SUN HOURS PER DAY  

See the chart and listings on pages 12 and 13. For example, the average for California is 5 peak sun hours
Step 4 CALCULATE THE SYSTEM SIZE (AC WATTS) TO PROVIDE 100% OF YOUR ELECTRICITY  

Divide your daily average electricity use by the average sun hours per day. For example, if the daily average electricity use is 30 kWh, and the site is in California, then the system size would be: 30 kWh / 5 h = 6 kW AC
Step 5 CALCULATE THE NUMBER OF PV MODULES REQUIRED FOR THIS SYSTEM  

Divide the system AC watts in Step 4 by the CEC watt rating of the modules to be used, then divide by the inverter efficiency, usually 0.94 and you get the total number of modules required. (Round this number up)

Use the below chart to determine possible array size/inverter combinations

This chart shows inverter and module combinations for common modules used in grid connected systems. For a given inverter and module combination, the chart displays the acceptable number of series strings of modules and the number of modules per string for temperatures between 14ºF and 104ºF. Where the inverter will support more than one string of modules, the chart shows the number of modules that can be used with multiple strings. Sizing is accurate in locations where the maximum temperature is lower than 104ºF or the minimum temperature is higher than 14ºF. In locations where the minimum temperature is lower than 14ºF, the maximum number of modules per string may be lower. String sizes followed by *** may have some derating in full sun.

In the chart, the line labeled CEC Watts is the expected output of the modules at normal operating temperature, in full sun. The line below this, labeled Ratio, is the output at operating temperature divided by the label rating of the module. Modules with a higher ratio give you more actual output power per rated watt.

The approximate power output of a system in full sun will be the number of modules times the CEC rating of the modules times the inverter efficiency from second column on the table. Other factors, such as high or low temperature, shading, array orientation, roof pitch and dirt on the modules, will affect the system’s actual output.

String Sizing Tool

Permissible number of modules per string - 14ºFMinimum Temp. - 104ºF Maximum Temp.
Inverter Module Shell

Evergreen

 Kyocera Mitsubishi
SQ165 SQ175 EC-110-GL EC115-GL EC120-GL KC175

MF170
Brand & Model CEC Efficiency CEC Watts

149.1

 158.3 98.4 103.1 107.6 154.9 152.5
CEC % of nameplate

0.904

 0.905 0.895 0.897 0.897

0.885

 0.897
SMA SWR1800U

91.5%

 one string 6 to 8 5 to 8 11 to 16 11 to 16 11 to 16 8 to 12 7 to 11
two strings 6 5 to 6          
SMA SWR2500U 93.0% one string 9 to 12 9 to 12 18 to 24 18 to 24 18 to 24 13 to 16 12 to 17
two strings 9 9 ***          
SMA SB3800U 94.5% one string 8 to 10 8 to 10 16 to 20 16 to 20 16 to 20 12 to 15 10 to 14
two strings 8 to 10 8 to 10 16 to 20 16 to 20 16 to 18 12 to 13 10 to 13
three strings 8 to 9 8          
SMA SB6000U 94.5% one string              
two strings 9 to 12 9 to 12 18 to 24 18 to 24 18 to 24 13 to 18 12 to 17
three strings 9 to 12 9 to 12 18 to 21 18 to 21 18 to 20 13 to 14 12 to 14
four strings 9 to 11 9 to 10          
FRONIUS IG2000 93.5% one string 7 to 8 6 to 8 12 to 20 12 to 20 12 to 20 8 to 14 8 to 14
two strings 5 to 7 5 to 7          
three strings 5            
FRONIUS IG3000 94.0% one string     12 to 20 12 to 20 12 to 20 8 to 15 8 to 14
two strings 5 to 8 5 to 8 12 to 14 12 to 14 12 to 14 8 to 9 8 to 9
three strings 5 to 6 5 to 6          
four strings 5            
FRONIUS IG4000 94.0% one string              
two strings     12 to 20 12 to 20 12 to 20 8 to 13 8 to 13
three strings 6 to 9 6 to 8 12 to 13 12 to 13 12 to 13 8 8
four strings 5 to 6 5 to 6          
five strings 5 5          
FRONIUS IG5100 94.5% one string              
two strings     12 to 20 12 to 20 12 to 20 8 to 15 8 to 14
three strings 8 to 9 7 to 9 12 to 17 12 to 17 12 to 17

8 to 11

8 to 11
four strings 6 to 9 5 to 8 12 to 13 12 to 13 12 to 13 8 8
five strings 5 to 9 5 to 6          
six strings 5 to 6 5          
seven strings 5            
XANTREX GT 2.5 94.0% one string 8 to 12 7 to 12 16 to 24 16 to 24 15 to 24 11 to 18 10 to 17
two strings 8 to 9 7 to 8          

XANTREX GT 3.0

94.5%

 one string 8 to 12 7 to 12 16 to 24 16 to 24 15 to 24 11 to 18 10 to 17
two strings 8 to 11 7 to 10 16 to 17 16 15   10 to 11
three strings   7          
XANTREX GT 3.3 94.5% one string 8 to 12 7 to 12 16 to 24 16 to 24 15 to 24 11 to 18 10 to 17
two strings 8 to 12 7 to 11 16 to 18 16 to 17 15 to 17 11 10 to 12
three strings 8 7          

String sizes followed by *** may have some derating in full sun.

WE ACCEPT...

Sign up for PayPal and start accepting credit card payments instantly.

All transactions made on this site are secure and Hacker Safe. 
Your Payments are processed for Taos Green Solar at SolarTaos.com
through PayPal, a trusted company owned and operated by eBay.com

OUR PRICEs in this catalog subject to change without notice. 
 

 If you are interested in quality supplements, please click on the above logo.
If you are interested in becoming a part of our USANA sales team, please click here.
 

Visit

Great gifts from Taos and northern
 New Mexico


Woodcare
Products
    Another Site by Artes del Lobo. Created & Maintained by Terry R. Wolff, Taos New Mexico
    This page last up-dated on June 25, 2010