Well the energy recovered from plant lights is actually really pathetic when using standard panels. Had to switch to amorphous panels which capture just enough energy to keep the battery sustainably charged day after day under typical loads.

Overall, the system reclaims just enough energy to run the air pumps for up to about 15 minutes total daily use. That’s plenty to achieve the goal of giving the plants a short soak in the nutrient medium which just drains away when the pump stops. It also facilitates filtered fresh air exchange and aeration of the liquid medium which is vital.

The next stage will be to make the system more thrifty with power (MOSFETs instead of relays and other tweaks to reduce current leakage when the microcontroller is asleep).

I want to add the ability to inject CO2 and monitor levels before I consider the product full-featured. Recent studies are showing that can result in huge gains in growth rates. Based on my estimates, a 16g CO2 cartridge (think paintball or whipped cream) can keep a typical 3-liter culture vessel at 4000ppm (10x over atmosphere) for a year, even if you completely flush with fresh air twice daily.

Thank you for your question and interest in my latest obsession.