12V Battery System: Up to 520W of solar panels (e.g., 1 x 550W panel or 3 x 170W panels).24V Battery System: Up to 1,040W of solar panels (e.g., 2 x 550W panels).The 9W Bulbs: These are highly efficient. On a full 150Ah battery, 4 of these bulbs could run for over 40 hours straight.