Jishi Jin

Hi everyone, I am Jishi from China, a researcher in vegetable breeding and culture. Like you, I am concerned with huge energy consume for greenhouse production, especially in cold winter and hot summer. And in developing countries like China not many farmers can afford to heat or shade, so products suffer from extreme climate. It hurts to see those pain faces due to loss from destroyed vegetables. For years I was searching for an alternative for greenhouse environment control, efficient, reliable and low cost. Here the solar roof seems a promising solution. Of course the structure of greenhouses in China differs from those in other counties. And here we have to adapt bubble and solar energy technology in a way so farmers with limited knowledge can operate it. I will update our progress and I expect to receive your kind support during the course. For the first step, can anyone tell me how to dehumify the greenhouse if the system is a closed one? Our problem here is in the morning the RH of the greenhouse is rather high and usually we have to open the top to let the vapor out, but it does not seem feasible for solar roof system.

Welcome Jishi, Thanks for participating and bringing another global perspective on our efforts to support sustainable food + energy production which can be localized with the methods provided by Sola Roof.

It is important to control humidity and we do this with Sola Roof by controlling the interior cover temperature. If this inner film is chilled by water then it attracts and condenses the moisture from the air within the building in a closed system. During the day also the liquid cooling system can remove the plant transpired humidity from the closed atmosphere and the allows recovery of pure water which condenses on the inner cover. The inner surface of the transparent cover material should be "anti-drip" and slope to the condensate collector where the condensate falls into the condensate gutter.

Most solaroof projects use the bubbles and ventilation and do not use the liquid film cooling. They are plastic film covered tunnels and use exhaust fans or a natural cross ventilation from one end to the other end of a tunnel.

Thanks Rick for your detailed information. Also in China we use natural ventilation. My doubt still is that if we leave that ventilation uncovered, will it not affect temperature inside? Another problem, maybe not your concern, is that small insects, like white fly or thrips will fly in through ventilition, even if we have insect netting.

In my perspective perfect system is one that seperates greenhouse from outside environment, that not just controls temperature and light, but also insects and even diseases. In this way can contribute better to sustainable production, do you agree to extend the solaroof concept to this aspect?

I think the cooling and dehumidification of the greenhouse in a closed system with no venting is very important for the reasons you have stated and the ability to keep out pests and disease is a capability that is possible when we use the thin liquid cooling system on the inner skin. Like the Bubble Tech this liquid cooling is not high tech but the results and benefits are substantial. This method can completely replace ventilation - but then we must supply the CO 2 at high PPM so that the plant growth is rapid. The CO 2 enriched environment that is contained is a way to get food without a big "carbon footprint". - Sola Roof Guy

I am interested in the liquid cooling system. Are you sure the humidity inside the greenhouse will not rise when we use this system? The humidity tends to be highest early in the morning, when the temperature is still low. Can we heat up a bit then? As to CO 2?, sometimes in China we grow mushrooms side by side with vegetables, which emitted big quantity of CO 2? in the day, and, in the end, we can harvest delicious mushrooms as a by product.

Yes, the Sola Roof methods can prevent the problem of dew forming on plants in the early morning (causing fungus disease) since the Bubble Tech method will prevent the rapid chilling of the air due to the insulation value and the radiative temperature - this prevents the leaf temperature from going so low as to condense humidity. The warmer air will hold the moisture. If necessary chill water film can force RH low enough to prevent dew on leaf surfaces. During the day the solar thermal energy is removed by the process of condensation of transpired moisture on the chilled inner skin. - Sola Roof Guy