Solar Insulation Meter (June 1, 2017)
designed by David A. Johnson, P.E.
You donít need a fancy and expensive meter to measure the sunís intensity. With some inexpensive parts you can build your own meter. I used a 1ma meter movement and a single solar cell I got on eBay with an area of about one square inch. I calibrated the meter on a very clear bright summer day when the sun was directly overhead. I pointed the solar cell for the maximum deflection on the meter and then adjusted the 100 ohm variable resistor R2 for a full scale reading.