This Web Application uses Leaflet Js Libraries to draw a polygon over Open Street Map and measures it's area and calculate the nominal solar power that can be generated with the solar installation in polygon.

For Demo: https://fidars.github.io/Polygon-Map/

Steps:

1. Draw a Polygon with the Measure tool on top right corner
2. Click on Map
3. A pop up shows on the drawn polygon showing the power in W

Nominal Power or Peak Power is calculated using Power = (Solar Irradiance) x Area x (Efficiency of PV) Solar Irradiance under Standard Testing Conditions: 1] 25 Degree C 2] Sun Perpendicular to Earth 3] Solar Irradiance= 1000 W/ Sq m (Approx) Area in Sq m Efficiency of PV in % (Consider a value between 14% - 20%)

example: 
  Area= 10 Sq m
  Efficiency: 15% = 0.15
  Solar Irradiance= 1000 W/ Sq m
  
  Power = 1000 x 10 x 0.15
        = 1500 W