Solar Powered Automated Greenhouse with modular support


When my team was brainstorming ideas for a fun, hands on capstone project, we had the idea of something relating to automatic plant watering. I already had experience with this in my past HackUNT project, and a couple of the other guys had used other various sensors like the DHT11 Temperature and Humidity sensor. We later found out that our professor actually had a personal greenhouse and had pitched the idea of a project involving solar energy to power the greenhouse.


When we started on the greenhouse, we were actually picking up on a legacy project that 2 groups prior had worked on. While our professor had told us a lot of great things about their user interface and ease of use, he hadn't mentioned how the construction and organization of the electronics had fared. The main problem that we would have had if we were to reuse the old group's project was that all the wiring and electronics falling apart. They had opted for cheap, plastic connectors on their wiring instead of crimping or soldering wires together. We also found a lot of the hardware to be either burned out or not calibrated anymore, probably due to the Texas heat causing problems.


Once we had cleaned out the greenhouse of the old group's project, we set to work on doing some basic construction needs, such as burying the hose that led from the home spigot to the water supply pipes in the greenhouse. We also constructed a stand for 2 solar panels that we had borrowed from our lab room, along with two 12 volt batteries. This solar power system would be managed by a solar charge controller, which we were able to purchase from Amazon.


The next step was to construct and test out the "water tower" watering system. The idea I had when I pitched this ideas was that by using an elevated water source and letting water flow down to solenoid controlled pipes, the need for water pumps to pump water out would be redundant, and energy could be saved while keeping the system efficient on water usage. Water could be continously provided from the home spigot, since the water pressure is generally sufficient for the small distance of piping we are covering, and the water will only flow when neeeded, like on a garden hose with a spray nozzle. So, the concept being that the hose is hooked up to a PVC pipe, which has a solenoid valve and a water level sensor that only fills the bucket with water when needed.


For the sensor controls and other various electrical systems in the greenhouse, our team decided to use a WeMos D1 R2 board. For those unfamiliar, this board is very similar to the Arduino Uno microcontroller, except the WeMos boasts a built in WiFi chip that allows for data transmissions over a network. The greenhouse already had a WiFi extender for the home WiFi, and it was simple to setup on the Arduino IDE (which is used for the WeMos board as well). This board also has an array of digital I/O ports, power supply and ground ports, as well as one analog port. The I/O ports allow the sensors to communicate with the WeMos board and provide the necessary data to be able to tell when to turn on and off control systems, as well as get the data uploaded to the database in order to be viewed on the website.


Watering the plants was mainly done through a soil moisture sensor hooked up to a WeMos board. The soil moisture sensor returns a percentage of soil saturation, and our team used this data to compare against a set threshold to tell if a plant needs water or doesn't. If a plant needs water, then the WeMos will signal to a relay hooked up to our 12V batteries to turn on the correct solenoid valve to allow water to flow for short period.


We also did an automatic HVAC system by splicing into the power cable of the large exhaust fan in the greenhouse. We could then use a WeMos board to control a relay that was linked to a DHT22 Temperature and Humidity sensor, which would return accurate metrics on the conditions inside the greenhouse. If it got too hot in the greenhouse, the relay would be activated, and the exhaust fan would be turned on. Due to the power demands of the exhaust fan, lighting, and other auxiliary functions, those were run off of an extension cord hooked up to the home power outlet. Everything else inside the greenhouse is 100% solar powered, automated, and ready to keep plants alive on a daily basis.


The idea for the "IoT" part of the greenhouse came from the fact that a lot of the information that we had used for putting together all the hardware and software had come from a multitude of internet sources. We figured that if we could make a centralized hub of helpful tutorials, that future users would have an easy time constructing their own greenhouses and would be easily able to add new features. Our greenhouse does have room for modularity, such as expansion slots on the PVC piping and fuse box for even more plant capacity. The goal here is to make the process simple enough that someone with basic technical knowledge could construct their own automated greenhouse that would be a lot cheaper and a more rewarding experience than a commercial greenhouse.


Responsible for: Hardware work, software support, water bucket tower design implementation


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