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The Photovoltaic Calculator

How the PV Watt Calculator Works



If you are thinking of installing a photovoltaic (PV) system to supplement your electricity consumption or to disconnect from the electric company then the worksheet below provides a simple way in which you can calculate economic feasibility of installing such a system. Visit our RE Directory to see a list of organizations and skills.

This calculator can help you understand the various tradeoffs that may be involved in using this increasingly popular renewable energy technology.


Follow the simple steps below:


  • Enter monthly electricity consumption KWH
  • Enter Costs to acquire Electricity Connection US$
  • Enter Cost per KWH (Average Costs for the Caribbean Region US$0.22)
  • Enter the yearly percentage increase in electricity (if envisaged)
  • Enter the yearly percentage decrease in the time value of money (if envisaged)
  • Enter Full Average Daily Sunshine Hours (Caribbean Average 5.5 hours per day)
  • Enter PV System Cost Per Peak Watt i.e. Costs associated to acquiring batteries, inverter, batteries, a charge controller, and miscellaneous other items. Cost is generally roughly proportional to the peak wattage capacity. (average cost per Peak Watt)
  • Enter Yearly Cost for PV System i.e. maintenance cost envisaged if any.



  Electric Consumption (KWH/Month)  
Electric Utility Photovoltaic System
  Grid Attachment Cost
  Average Full Sunlight/Day (hours)
  Electricity Cost ($/KWH)
  PV System Peak Wattage Requirement (dc)
  Percentage increase in electricity per year
  PV System cost per peak watt (US$)
  Percentage decrease in the time value of money
  PV System Yearly Expense
   
  PV System Lifetime (years)
Comparative Cost US$
  Utility
 
PV

 




Notes

Current monthly electric consumption in kilowatt hours. This value will be used, along with the average hourly sunshine, to calculate the peak power capacity of a PV system. It will also be used in calculating the value of the electricity that you are likely to displace by installing a PV system.



ELECTRIC UTITLITY


Grid Attachment Cost - Attachment to an electric utilitiy's grid is usually pretty much free. However, if the grid is not available, you may have to bear the cost of poles, wires, and transformers to your site. If so, enter the cost of that here.

Grid Electricity Cost - Enter the cost per kilowatt hour of electricity provided by your utility. This will be used in calculating the value of the electricity displaced by your PV investment.



 

PHOTOVOLTAIC SYSTEM


Average Daily Sunlight Hours - Enter the average hours of sunlight that you receive in a day. This value will be used, along with your average electric consumption, to calculate the peak power capacity of a PV system to meet your needs. In the Caribbean this is typically 5.5 hours.

PV System Peak Wattage - Photovoltaic systems are rated according to the peak DC power that they can produce. The amount of AC energy supplied by a system is equal to this peak rating times the number of hours that the system receives full sunshine, times a derating factor that accounts for efficiency losses in the system (wires, inverter, etc. - we use 75 percent). This field is calculated, based on the average hours of daily sunshine and your monthly electricity requirement. However, if you enter a value, it will be used, with the peak sunshine hours, to calculate an equivalent monthly electricity usage in KWH

PV System Cost per Peak Watt - In addition to the PV panels, you may need to purchase an inverter, batteries, a charge controller, and miscellaneous other items. Cost is generally roughly proportional to the peak wattage capacity.

PV System Yearly Expense - Unfortunately, you may need to occasionally spend money on your personal PV powerplant (for example, replacing batteries). If you project an average yearly expenditure for such things, enter this here. The lifetime value of this expense will be subtracted from the displaced grid electricity cost.

PV System Lifetime - A Photovoltaic system's high initial cost is offset by the free energy that it captures, so lifetime is very important. Enter the projected lifetime of this PV system in years.

 



COMPARATIVE COST


Displaced Grid Electricity Cost - The electricity that your PV system produces displaces energy that would have been bought from the utility company. This calculated field is the value of that electricity that you won't be buying.

Photovoltaic System Cost - The calculated cost of your photovoltaic system appears here. It includes the base cost plus the yearly operating expense over the lifetime of the project. Compare this to the value of displaced grid attached electricity to check your investment.

 

 

 

 

 




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