About this app

Use the light meter, on your phone or tablet, to measure sunlight strength in watts/m²
Track and share sun position (azimuth and elevation) anywhere in the world, on any date
Solar air heater calculator helps determine output in BTU or watts from a solar heater
Wirelessly connect to Okapi Solar Air Heater control systems for real time data viewing, data logging and much more!


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Solar and HVAC calculator:
Enter measured temperatures from Inlet and Outlet (°F or °C)
Enter measured wind speed from the outlet (FPM or m/s)
Enter dimensions of the outlet (inches or cm), diameter or rectangular
Select if equivalent diameter calculation (Huebscher) is required for rectangular outlets
Enter elevation or have the App calculate it automatically using GPS and an internet connection

App calculates:
Temperature rise between inlet and outlet
Output from the system in watts or BTU
The area of the Outlet
The airflow (CFM or m³/min)
The F value (specific heat of airflow mass), which is based on the elevation
Unit conversions are also available: convert between °F and °C, between cm and inches (including squares and cubes), convert between watts and BTU.
Share button to allow sharing to social media, email etc.


Sun position activity
Choose a location using GPS or the built-in Google map
Automatically determines the Timezone (internet connection required)
Or enter the timezone manually
Choose a date if you want a forecast or historical data
The app displays sunrise time, solar noon time and sunset time
The app displays the current azimuth and elevation of the sun
Use a slider to slide all the way from sunrise to sunset and watch the solar azimuth and elevation change as you alter time
Built-in compass (requires specific sensors and works best outside)
Shows you the pitch of the Android device. Great for measuring sloping angles!
All above output data can easily be shared via email, social media etc.
Specify level of detail in shared data via options


Estimate Sun strength (like a Radiometer or Pyrheliometer)
Uses light sensor on Android device to measure sun strength (irradiation) in watts/m² or BTUh/ft²
Toggle button to convert between watts/m² and BTUh/ft²
Share button available to send your data via email, social media, Bluetooth, Google cloud print, Google+, Facebook, etc



Okapi wireless system required for following features


Okapi real time data monitoring!
Connects Android device via Bluetooth to Okapi Solar Air heater control systems
Displays output for each connected heater: Inlet and Outlet temperatures in °C or °F, Temperature rise between inlet and outlet, fan speeds and thermal power output (kWh or BTUh)
While connected to Okapi system, app logs Okapi performance
Share Okapi real time data to email or social media such as Facebook


Data logging:
The app can be left running, while connected to an Okapi, system to log data
Database stores accurate hourly heating calculations
User ability to enter report queries and share reports for graphing or further analysis


Settings (for entry of detailed data regarding connected Okapi systems)
Detect elevation at the location of the solar heaters (GPS and internet required)
Calculates the F value (heat capacity of airflow mass) based on elevation
Set whether share data should be in detailed or basic form
Privacy option: Set whether or not you want to include your GPS location in share data

For each heater:
Name the heater
Set whether the outlet is round or rectangular
Enter the diameter, or width and height, of the outlet
Set whether equivalent diameter is required.
Enter the measured wind speed when the fan is running at 100% (FPM or m/s)
Enter the area of the collector's active surface area
Outlet area is then calculated for you, as is the Maximum airflow (in CFM or m³/min)
Convert between metric and imperial units

New features

Localization added for: Nederlands, Français, Deutsch, Svenska, Español, Italiano, čeština
Enhanced sunlight strength estimation: Additional controls implemented to both calibrate and fine tune the light meter readings
'Detect Elevation' added to Calculator activity