This is the physical design of the PV system and its interconnections with the First Energy Grid and the school's electrical system. In other words...this is the technical part to this project.
1. Solar Panels (Modules)
We have 5 solar panel modules on our roof located on the flat surface above the link building. Each panel is about 65 by 40 inches, weighs approximately 40 pounds, and has an angle of elevation of 10 degrees to allow for maximum sun exposure while not rendering it visible from the ground. Collectively, the units capture radiated energy (light) from the sun and transform it into electricity, sending it off into the power system.
2. Micro-Inverters (DC to AC):
Direct current, or DC, is an electric flow traveling in only one direction, and it is the type of power coming out of the solar panels’ modules. But outlets, as well as almost all other electrical components, only accept a type of electricity called alternating current, or AC. Alternating current is an electric flow that reverses its direction at regular intervals many times a second. Five micro-inverters, one for each solar panel, are required to convert the current type in our electrical system from the direct current of the solar modules to the alternating current of the receiving outlets.
3. Junction Box
This is essentially an 8-inch cube of metal where the powered wires from the micro-inverters and solar panels, now with alternating current, are combined neatly into one conduit-surrounded set of wires. It is used to transition from the thinner, more vulnerable wires of the modules to that of an organized, protected system.
4. AC Disconnect/Safety Switch
This is a switch that has the ability to completely shut the system down in case of an emergency. It is wired from the panels down the side of the school, and it is quite literally a manual lever on the side of the building. Mainly for safety measures, this is required by the fire department.
5. Electrical Panel “LPC”
This is the point in the electrical system where the electricity is separated in two directions, also known as an ‘interconnection.’ The energy from the panels is transferred to the utility meter and in turn, back into ‘the grid,’ while energy from the grid comes back through the electrical panel and sent to the outlet, for public use, and the enphase envoy, for observation and record.
Students and faculty can plug their computers into the electrical outlets in the charging station tables. These outlets draw power from the First Energy grid. The power does not come directly from the solar panels. However, we can track how much power we draw out of these outlets, as well as how much electricity we have produced with the PV array. Our goal is to use only as much power from these outlets as we have generated.
7. Envoy Gateway
This continuously logs data about our electricity production from the solar panels.
8. Utility Meter
This is the meter that measures the flow of electricity between "the grid" and HB. If our electricity production from the panels were ever to exceed the electricity being used in the building, this meter would run backwards. Our photovoltaic system is so small, relative to the amount of electricity that the school uses, that this meter will probably never run backwards. Instead, this meter will simply register a slightly lower total draw from the First Energy grid than it would have without the solar panels.
9. First Energy "Grid"
The First Energy electrical grid is the network of electrical generators, transmission and distribution lines, and control networks that move energy from energy producers to energy users. Rather than feeding into a battery bank, HB’s PV array is connected to "the grid." Energy produced by HB's PV system feeds directly into the school and is used within HB's walls. Only if our system produced more power than the circuit to which it is connected was drawing at any given moment (a near impossibility given how much power HB uses relative to the size of our system), would power generated by HB's PV system feed into "the grid." However, if the circuit requires more power than our system is generating at any given moment, the circuit will draw power from "the grid."