Early Adopters Education Module

a GVSU senior project component

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Renewable Energy Options

• Hydroelectric – harness flowing water to turn a turbine, which then causes a generator to produce electricity. This is done on a large scale with dams, however it can be implemented on a smaller scale as well.
• Wind – above ground turbines are spun by the wind to provide a generator with the mechanical work necessary to generate electricity. Wind farms are increasingly common both on land and offshore, where wind speeds are significantly larger.
• Solar – Photovoltaic (PV) cells capture sunlight and convert it into usable electricity. These systems can be installed on a small residential scale, on an industrial scale, or anywhere in between.

Why Use Solar For My Home/Business?

• Flowing water necessary for hydroelectric is not readily available for a majority of homes and businesses so individual hydroelectric power is impractical.
• Wind power requires a large footprint to erect wind turbines which is impractical for the average homeowner or business. Additionally, turbines are loud and unpleasant to have in a residential or commercial setting
• Solar panels or shingles can be installed on top of the existing structure provided it receives sufficient sunlight, eliminating the need for an additional footprint.

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 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 connection 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 (AC 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.

How are Power Systems Mounted?

• There are three methods to mount a solar panel system, while shingles can only be used as 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.

What components are required in solar power system? - On Grid

On Grid

• Solar collector (photovoltaic panels or solar shingles)
• Inverter (micro, string, mini)

Optional:

• Battery bank
• Charge controller

What components are required in solar power system? - Off Grid

Off Grid

• Solar collector (photovoltaic panels or solar shingles)
• Off grid compatible inverter
• Battery bank
• Charge controler

Solar Collection Methods

PV Panels

• Larger module footprint
• Higher efficiency
• Higher cost per module but typically higher output per module
• Less aesthetic value

Solar Collection Methods - Continued

Solar Shingles

• Smaller module footprint
• Lower efficiency
• Lower cost per module but typically lower output per module
• Higher aesthetic value

Inverters

String Inverter

• Connects a set of solar collectors in series to form a string. Some inverters allow for a set of strings.
• Shading on a single panel will significantly drop the output of the whole group
• Typically lower cost than other inverter types

Inverters - Continued

Micro-Inverter

• Connects to individual panels.
• Allows for partial shading of panels without significantly dropping total system output due to multi power point tracking (MPPT).
• Micro-inverters are typically designed for ON GRID systems. Some of these inverters determine their ouput by mimicing local grid characteristics (therefor require a grid to operate)

Inverters - Continued

Mini-Inverter

• Differing types of these inverters can be used for either ON GRID or OFF GRID applications
• Connects to individual panels, however some mini-inverters have multiple inputs for panels or even battery banks for energy storage. This makes them ideal for OFF GRID applications
• Like micro-inverters, these inverters can implement multi power point tracking (MPPT) on the panels connected to it.

What to do with Excess Power?

Sell it Back!

• Local utility companies are usually willing to buy back extra electricity in the form of credits applied to your monthly bill (net metering).
• Contact your provider to determine if programs are available in your area.

What to do with Excess Power?

Store it!

• Battery banks can be used to store electricity for later use.
• Be sure to properly size your battery bank for your needs.
• Include a charge controller to prevent overcharging the batteries, this will assist in extending battery life.

Battery Sizing

• To properly size your battery bank, determine the following:
• Average daily energy use
• Number of batteries required to sustain building load
• Solar system voltage requirements
• 50% depth of discharge on your batteries should be maintained (represented by the 2 in Equation 1 of the next slide).
• Remember to round up to next whole battery!

Battery Sizing - Equations

Equation 1
Using the amp hours value found, research batteries at and above that capacity.
Equation 2

Question 1 - Size a Battery Bank

Click or Tap 'show answer' to view the answer:

What is the minimum Amp Hour capacity and number of batteries for the following house:

The owners of a house want batteries to supply 1 day of electricity.

• Average daily use of 30 kWh.
• 120V system voltage.
• 100AH rated batteries
• Show Answer:

Equation 1

Expected System Lifetime

• Some solar panels are built to last 25 years however as they age their output decreases. Sometimes down to as low as 80% of their original output.
• Modern inverters are typically built to last between 20 and 25 years.
• Deep cycle batteries (often used in solar applications) typically have 10-15 year expected lifespans, however there is significant variance depending on the type of battery that you use (i.e. lead acid or lithium ion).

What Regular Maintenance is Required?

There is little maintenance 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 it out if the output dips unexpectedly.

Building Considerations

• Installation of solar panels and other components will require two permits before work can begin
• Building permit
• Electrical permit
• Homeowners can get a building permit with a disclaimer if they are not a licensed builder. Licensed builders simply do not have a disclaimer.
• Work under an electrical permit must be inspected by a certified electrical inspector. Typically a minimum of 24-hours notice prior to installation is required.
• Permits can be found online, as well as any supplemental information for the Authority Having Jurisdiction (AHJ), which changes with location.

More Building Considerations

• Manufacturers of solar panels and shingles include instructions for proper installation so the panels life is as expected, and so that the manufacturers warranty is not voided.
• If you want to install panels yourself, general construction knowledge will be required, such as finding rafters and roof trusses, so that the panels are properly anchored to the structure.

Homeowners insurance

• Generally the installation of solar power systems should not affect a homeowners insurance policy, but it is worth checking before you go ahead with an installation, just in case.

Tax Incentives

• Installation of any solar power system qualifies for the Investment Tax Credit (ITC) of 30% on your federal tax return.
• Note the ITC is a credit, NOT a deduction. This means that 30% of what was spent on the solar power system will be returned with your taxes.
• The solar ITC will remain at 30 percent for those investments that have began construction through 2019. The ITC will then step down to 26% and 22% in 2020 and 2021 respectively. After 2023 commercial and utility credit will drop to 10% while the residential credit will drop to 0%.
• All receipts or the final invoice are needed to prove how much was spent on the solar power system.

Effects of Solar Shading

• Inside solar panels, rows of photovoltaic cells are connected IN SERIES
• Which means that if the output of one cell decreases (perhaps due to shading) than the rest of the cells in series with it will experience the same decrease (think of it like putting a kink in a garden hose).
• This can effectively negate the contributions from a whole panel if just a corner is shaded.
• The effect is compounded if there are several panels connected in series with each other. All the panels in series will drop to the output of the lowest panel. This is where the multi power point tracking (MPPT) algorithms found in micro and mini inverters become desirable.
• MPPT is used to optimize panel outputs individually, preventing one shaded panel from interfering with the performance of other panels.

Tracking vs. Fixed

• Tracking systems will produce greater (often significantly so) system outputs as compared to fixed systems.
• Studies have found that both a one-axis and a two-axis tracking system will produce approximately 30% more PV power than an otherwise identical fixed system over the course of a day.
• However due to increased installation and maintenance costs of tracking systems, fixed systems are typically selected for residential and commercial use.

Potential For Savings

• Savings will vary based on location, but Google Project Sunroof itemizes costs and savings on Their site
• This calculator factors in many different methods of aquiring solar equipment, and breaks down how long it will take to pay back