Integrating Solar Power in Outdoor Sculpture
The summer interns were split into two teams, one whose focus was electronics and one whose focus was on structures. The structure team was tasked with designing and building three large scale public structures. One of the structure teams wanted to integrate solar energy and human interaction with their piece. This tutorial is specific to this purpose, but the basic circuitry is still valid and applicable in other cases.
How it works
Jake, Tresor and Kristna are building the structure, and Jake proposed to have visitors touch the flames on the outer part of the sculpture and red LEDs would light up on that flame.
We’ve decided to use two copper plates in the shape of hands, that will act as a trigger with enough resistance. That is where the Mosfet comes in, you want to think of it as a “smart” switch. When it has enough resistance for the gate(G)-to-source(S), it allows voltage to go through the drain(D), which is connected to the LED, which makes it light up.
Solar panels are made out of Solar cells or photovoltaic cells. These cells are extremely thin cells made of silicon , carbon, hydrogen, and oxygen to collect solar energy and convert it to direct sunlight. Solar cells first have to be gathered up together to be able to make a solar array. The Solar array has to be hooked up with an existing power grid because in that way if your panels ever malfunction you could still receive power. A power grid-tie system is mostly aligned with many government incentives.
Its uses are to store an infinite storage system, eliminating need for batteries. There are many benefits to solar power because it’s a renewable source, meaning that we can never ran out of it. Solar panels are also non-polluting like fuel or other chemicals that emit carbon dioxide or spills that harm the environment. However there are some disadvantages to solar power, for example the power of the panels drop a lot at night and other panels take too long to adjust to the light of the sun. Clouds may also interfere with the process because it could block the sun light. The silicon and the photovoltaic cells could also get destroyed if they’re exposed to the sun for extended periods of times, also water and dirt could damage them if not taken care properly.
We will be optimizing the tilt for winter. As we are in the Northern Hemisphere, we will point them towards true South. For our location in City Heights, San Diego, we need to place the panels at an angle of 58.43 degrees from horizontal.
- Solar Panel (5W, 12V) $40 from Harbor Freight
- Gel Cell Battery (12V,14Ah) $20-$30 from Batteries Plus
- 1 Amp Solar Charge Controller (regulator) (1-2 Amp) $20 from Fry’s
- Christmas Lights (12V)
- – 1 k ohm
- – 500 k ohm
- Mosfet IRF540
The solar panel is connected to the solar charge controller on the solar panel side. The battery connects to the controller as well, on the battery side. The controller allows more regulation than a low-voltage diode (like a Schottky diode) and allows for precise control over electricity flow from the solar panel into the battery.
The other half of the circuit is actually composed of the copper hands, the mofset, the two resistors, and the lights. This part can be replicated as many times as needed to place lights in different areas of the sculpture, allowing for interaction with more people.
The mofset acts as a “smart” switch (see above description). When someone touches both plates, that closes the circuit and makes the mofset move electricity into the leds.