General Public Education Module

a GVSU senior project component

Click the arrows, use your arrow keys, or swipe to advance slides

What does PV stand for?

• PV stands for Photovoltaic
• Etymology
• Photo is derived from phos, the Greek word for light
• Voltaic is derived from volt, the English word for electrical potential

How Does Solar Energy Work?

• There are two types of solar energy systems: ON GRID, and OFF GRID
• On grid systems have a connection to the local power grid, and allow for electricity to be produced by the solar sources to be supplemented with power from the grid, if the output is too low, or the electricity can be sold back if there is excess production.
• Off grid systems have no connectino to the local grid, instead they have deep-cycle battery banks which are used to store electricity for use when the solar sources are not producing enough electricity. The stored electricity comes from times when there is an excess production of electricity.

How Does Solar Energy Work? - On Grid

• Solar cells in PV panels or shingles collect sunlight and convert it to direct current (DC) electricity.
• The DC electricity travels through an inverter, converting it into alternating current (AC) electricity. (This is what comes out of the outlets in your home).
• From the inverter, the electricity is either sent into the powered building for use, or sold back if it is not needed.
• If the electricity is sold back, it travels through a meter to measure how much electricity has been sold back to the utility company so that the proper balance is paid by the utility company to the property owner.

How Does Solar Energy Work? - Off Grid

• Just like on grid systems, solar cells collect sunlight and convert it into DC electricity.
• The electricity is sent to a charge controller, which manages the charging and discharging rate of the batteries, so that they are never over-taxed or over-charged
• From the batteries, the electricity needed to power the building is drawn into the inverter, to once again convert from DC to AC electricity.
• The AC electricity is then supplied to the building for use.

Question 1:

Click or Tap the option that fills the blanks:

• a) store surplus electricity in batteries, sell surplus electricity
• b) burn surplus electricity, store surplus electricity in batteries
• c) sell surplus electricity, burn surplus electricty
• d) sell surplus electricity, store surplus electricity in batteries

In What Conditions Will a Solar Power System Work?

• Several different factors can affect the viability of solar collection systems such as:
• Weather
• Location (on the planet)
• Environment (surrounding topography)

What Weather Conditions can a Solar Power System Withstand?

• Rain is anticipated by solar panel and shingle manufacturers, and they are ensured to be waterproof, thus even strong downpours are not an issue.
• Solar panels are rated to withstand impacts from objects such as hail, up to 1” in diameter at 50 mph.
• Wind is also anticipated, so panels are mounted on brackets which are secured to the load bearing structure of the roof. Solar shingles are equally as susceptible to wind as normal shingles.

What Weather Conditions can a Solar Power System Withstand?

• Arid regions, such as the south-western United States, will need to ensure that solar sources remain free of dust and loose debris that could be blown onto the collectors over night or over time. Buildup can cause electrical production to be significantly lower than expected.
• In locations where snow is a factor, panels are designed such that the snow will typically be sloughed off naturally throughout the day. In extreme circumstances, snow should be removed from the panels to prevent excessive amounts of weight from building up.

Where Will a Solar Power System Work?

• A solar power system can be installed anywhere on Earth with the exception of the poles.
• As Earth orbits around the sun, it is on a tilted axis. This means that at times certain parts of Earth are closer to the sun and some are further away.
• To get the largest amount of electricity production from PV cells, they should be facing the sun as squarely as possible.
• This is accomplished by tilting the PV cells to a specific angle given the latitude of the location. These angles can be found at various sites online.

What Environment can a Solar Power System Work In?

• Any shading of solar panels or shingles will reduce their output, so the more a location has direct sunlight throughout the day, the greater production there can be from a solar power system.
• Extreme humidity can significantly reduce the efficiency of a solar power system, so less humid areas are ideal.

Question 2

Click or Tap the option that fills the blank:

Solar panels should not be used if ______.

• a) the area is heavily shaded
• b) the area can receive snow
• c) the area receives heavy rainfall
• d) there is strong wind blowing around the panels

Question 3

Click or Tap an option:

(True/False) Solar power systems should only be installed on the north and south poles.

• True
• False

Question 4

Click or Tap the option that fills the blank:

High humidity causes a solar power system to ______.

• a) put free electricity into the air
• b) increase efficiency
• c) decrease efficiency
• d) operate as usual

How is the Power System Mounted?

There are three methods to mount a solar panel system, while shingles are only used in the same fashion as traditional shingles:

• Two-axis tracking - allows the system to follow the sun on its' east-west journey each day. It also allows for the north-south tilt angle, which will gradually change with the seasons, to be adjusted periodically.
• One-axis tracking - allows the system to only follow one of the two paths of a two-axis tracking system.
• Fixed - the system is completely restrained and has no motion. Residential and light commercial roof installations are typically fixed.

From here on out, we will focus on a fixed system.

What Regular Maintenance is Needed?

There is little maintenance needed for the overall system, as there are no moving parts, but consider the following:

• Clean off the exposed the glass periodically, especially if you live in a dusty or windy climate, any debris can block some light and reduce your system output (imagine never cleaning your car windshield!)
• Monitor your system output, so you know to check the system if the output dips unexpectedly.

What Components Does a Solar Power System Need?

• On Grid
• Solar collector (panels or shingles)
• Inverter (micro or string)
• Optional:
• Battery bank
• Charge controller
• Off Grid
• Solar collector
• Charge controller
• Battery bank
• Inverter

Solar Collection Methods

• Panels
• Larger footprint
• Higher efficiency
• Lower cost
• Less aesthetic value
• Shingles
• Smaller footprint
• Lower efficiency
• Higher cost
• Higher aesthetic value

Inverters

• String Inverter
• Accept from multiple collectors
• Generally used with panel groups
• Shading on a single panel will significantly drop the output of the whole panel group
• Lower cost
• Micro-Inverter
• Only accepts input from one collector
• Generally used with shingles
• Allows for partial shading of panels without significantly dropping overall output
• Higher cost

Question 5

Click or Tap an option:

• (True/False) You need a battery bank for an on grid system.
• True
• False

Question 6

Click or Tap the option that fills the blank:

Microinverters work with ______.

• a) Only solar shingles
• b) Only solar panels
• c) Groups of panels or shingles
• d) Individual panels or shingles

What to do with Excess Power?

• Sell it Back
• Local electric companies are usually willing to buy back extra electricity in the form of credits applied to your monthly bill. This is called net metering.
• Contact your electricity provider to determine how to set this up
• Store it!
• Battery banks can be used to store electricity for later use.
• Be sure to properly size your battery bank.
• Include a charge controller to prevent overcharging the batteries.

Battery Sizing

Properly sizing a battery bank will require the following metrics:

• Average daily energy use.
• How man days you want the batteries to sustain the building.
• System voltage

Expected System Lifetime

• Solar panels are built to last over 25 years. As they age their output decreases down to as low as 80% of their original maximum output.
• Modern inverters are made to last between 20 and 25 years as well.
• Batteries are generally good between 10 and 15 years, however there is significant variance depending on the type of battery used.