Awesome. The XBee module is an RF module, the XBee Pro S3B. I just remembered, while the apogee sensors I am using don’t require power to make measurements, they do require power for the internal heater. The pyrgeometer heaters, according to the datasheet, draw 15.4 mA and 185 mW at 12 VDC. The pyranometers draw 30.8 mA and 370s mW at 12 VDC. In total there are four apogee sensors (two pyrgeometers and two pyranometers). Do you think it is still a similar situation @shicks that the 4400 mAh battery and 5w panels are sufficient?