Cool mega array with silicon on thin box (CMA-SOTB) is an extremely low power coarse grained reconfigurable accelerator. It was implemented by using the SOTB technology developed by a Japanese national project, low-power electronics association & project (LEAP). Making the best use of such a device and low energy architectural techniques, CMA-SOTB works more than 25MHz clock with less than 0.3V supply voltage. Various kind of optimization can be done by controlling the body bias voltage for PE array and micro-controller independently. The demonstration using CMA-SOTB first shows that a simple image processing application can work with a 0.25V-0.4V solar battery. Then the leakage power control by changing the body bias is demonstrated. In the stand-by mode, less than 20μW power is consumed by using strong reverse bias.