LED lighting
LED Inverse of PV Benefits from the same cost curve
Form factors
Pi Zero
$5 1Ghz, Single-core CPU 512MB RAM Mini HDMI and USB On-The-Go ports Micro USB power HAT-compatible 40-pin header Composite video and reset headers
Pi Light Light control protocol - measure - actuate
GreenLight
How big a store? 7.4 V 2200 mAh = 16.2 Wh 1 5W LED for 3 hours $9.19 from Staples! All prices decreasing exponentially