Photovoltaics

Photovoltaics (PV) systems convert sunlight directly into electricity through the use of semiconducting materials. During the daytime, the sun's energy excites electrons within the material, resulting in electricity flow to power appliances within your home. PV systems provide a clean and low maintenance source of renewable energy, but are relatively expensive to install. Financial incentives from both federal and state government agencies are periodically available which can help to reduce the PV initial costs. 

To understand if a PV system is right for your home, you should determine if your site is viable for the PV system by conducting a site assessment and understanding the PV system types, sizes,  power outputs, the cost effectiveness, and their payback period. You can check out federal and state incentives for solar installation in Ohio.  A virtual tour of example homes in Ohio that use PV systems can be found at greenhome.osu.edu/virtual-tour.

Site Assessment

A site assessment for PV systems helps to determine sunlight access at the site, potential locations, and orientation for the PV system. It is recommended to contact a professional in your area to do the site assessment at Green Energy Ohio’s “Ohio Renewable Energy Installers List” webpage.

For a do-it-yourself site assessment, please follow the following steps:

1. DETERMINE THE TRUE SOUTH

True solar south is not the same as the magnetic south, i.e. the south direction that a compass points to. For Ohio, the magnetic south is 5° - 8° east of the true solar south.8

2. DETERMINE THE INCLINE OF YOUR SOLAR PANELS

The incline of your solar panels affects power generation of the PV system. For fixed-oriented PV systems, most homeowners orient the incline of the solar panels to the latitude angle. A tool to calculate the incline angle is available.10

3. DETERMINE IF YOU WANT A SUN TRACKING SYSTEM

You can opt for a more efficient single-axis or dual axis tracking system that uses light sensors to follow the sun in the sky. These systems have moving parts; typically cost more than fixed systems; and then may incur high future maintenance costs. 

4. DETERMINE SHADING PATTERNS

Lastly, determine if there are any intrusions that may cause unwanted shading on the PV system throughout the year. This can be done using a sun-pathfinder.11

PV System Types

PV systems come in various electrical arrangements. Stand alone and grid tied systems are the most common types, though other systems exist. Some require battery electrical storage which can be costly for larger systems, while others do not require batteries.

Stand Alone

An off grid system that requires batteries for electricity storage. These systems have the highest initial and long-term costs, but allow for energy independence from the grid.

Grid Tied

The PV systems are directly connected to the power grid, which allows excessive electricity produced to be fed into the grid and tracked using net metering. This is the cheapest and most common system type in Ohio, but this system will go down if the grid power is shut off. There is no battery required for this type of system.

Grid Interactive

Similar to grid tied, except you can cut the grid out via a bimodal inverter for use on critical loads when the grid power goes out. Battery storage is required, which leads to more expensive initial and long-term maintenance costs.

Grid Fallback

The grid and the PV system will both charge a battery that supplies both AC and DC loads.  

Hybrid System

A system that uses other renewables sources of energy, such as wind, generators, hydroelectric, etc. to produce energy to supplement a battery/grid tied system. Batteries are optional for these systems.

PV solar collector types

Photovoltaic solar collectors come in many different types, each having their own advantage and disadvantage. In this section we will discuss three main types of photovoltaic collectors used in residential applications.12

Monocrystalline

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Polycrystalline

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Thin-Film Solar Panels

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System Sizing

System sizing can vary based on the type of system and the power output you desire. To correctly size your PV system, please contact a PV professional or a renewable energy provider. visit: alternatively, you can follow a PV sizing calculator by Wholesalesolar to size your own PV system.

Cost Effectiveness and Payback Period

With such a large investment, surely you will want to know how quickly solar may pay itself off. The cost and payback period vary widely based on your home’s electricity rates and usage, PV system outputs and efficiencies, and incentives available. A DOE tool can be used to estimate the power outputs of your PV systems based on the system size and other parameters. PV systems typically take more than 20 years to payback. With financial incentives, the payback periods can be reduced. Learn more at “Solar Power Incentive and Rebate Information Page” provided by solarpowerrocks.com. You will want to determine your potential payback period by talking to a professional solar installer who can assess your site specifically. You can find a list of professionals uisng "Ohio Renewable Energy Installers List" by greenergyoh.org. 

Incentives

Currently there are no rebates or incentive programs in Ohio for PV projects. However, there are Solar Renewable Energy Credits (SRECS) available in Ohio. SRECs reward you with a SREC credit for every 1 MWh of electricity you produce. You can then sell SRECs to utilities or other organizations. Currently SRECs are around $15 per 1 MWh, but have historically been as high as $400 per 1 MWh  in 2010. The good news is solar PV systems do add value to your home, and Cleveland and Cincinnati allow you to keep this added value off of your property taxes. Unfortunately, all other cities in Ohio do not allow this.15

You can learn more about current incentives by visiting "All Incentives" by energizeohio.osu.edu.

 

Resources

1 "Economics of solar electric systems for consumers: Payback and other Financial Tests" by Andy Black

Learn about economic payback considerations of solar implementation.  

"All Incentives" by energizeohio.osu.edu

Search for incentives in your area specific to your county, application, and utility provider. 

"Ohio Consumer's Guide to Buying and Solar Electric System" by greenenergyohio.org

A guide for purchasing a photovoltaic system in Ohio. 

4  NREL's PVWatts® Calculator

Estimate the performance of your potential photovoltaic system using National Renewable Electricity Laboratory software by the Department of Energy.

5 "Issues and Policies" by Solar Energy Industries Association®

General background information related to solar. 

6 "Solar Photovoltaic Technology Basics" by National Renewable Energy Laboratory

Short intorduction to photovoltaic technology. 

7 "Basics of Photovoltaic Technologies" by the Department of Energy

Introduction to photovoltaic technology and how it works. 

"How to find true south for aligning solar collectors" by rimstar.org.

Method for determing true south for your location. 

9 "Database of State Incentives for Renewable & Efficiency®" by dsireusa.org

Incentives by location. 

10 "Solar Angle Calculator"

Calculate the solar angle for your home's solar collectors.

11 Example Solar Path Finder 

Background information for solar path finders. 

12 "Which Solar Panel Type is Best? Mono- vs. Polycrystalline vs. Thin Film" by Mathias Aarre Maehlum of energyinformation.org

Background information for panel material types. 

13 "Rewewable Energy Installers List" by greenenergyoh.org 

Renewable energy installers directory.

14 "Steps for Designing Your Own System" by wholesalesolar.com

Four interactive steps for designing a photovoltaic array. 

15 "Power Incentives and Rebate Page" by solarpowerrocks.com

Great background on current incentives in Ohio. 

16. "What Are Solar Cells? Everything You Wanted To Know" by Anna Kucirkova

A comprehensive introduciotn of Solar Cells and the recent advances.