Editor’s note: The Prechel home was one of six on view in Oak Park for the Illinois Solar Tour on Oct. 1. Alan Prechel’s installation was unique on the tour because his was primarily a “do it yourself” project. If you are considering solar for your home or business, whether you plan to hire a contractor or not, you will be better prepared for the task after reading Alan’s account, his steps and decisions, his hints and cautions, and his successes and failures.
Author’s note:Please remember that I researched, designed, purchased, and self-installed my system in order to keep the total costs feasible. I hired professional help when needed and went through the required channels with the utility and municipality to ensure this system is safe and well built. You should do your own research as I did, even if you are leaning towards hiring a solar contractor to do the labor. Best of luck, I hope you have many sunny days ahead!
By J. Alan Prechel
There are many reasons Solar energy is ‘disruptive’. The term carries with it massive environmental, economic, social, and political weight. Energy produced by Solar PV systems is clean; no carbon emissions or pollution is generated for the 20+ years a typical system will operate. Additionally, the generated power earns the owner SRECS (renewable energy credits) used by businesses to offset their dirty pollution footprint. Most PV systems can be designed to reach ROI (return on investment) well within the lifetime of the equipment, and thus they create monetary profits thereafter. System owners are insulated from utility rate hikes and inflation and are less dependent on external energy sources.
I believe if Solar PV were the norm in US residential applications there would be no energy crisis, our grid and infrastructure could be modernized to promote sharing instead of commercial interests, and our political foreign-oil policies would be flipped on their heads, but that is a conversation for another time. If you are interested in going Solar, I have laid out a few steps to guide you on that path.
1. To go Solar first get GREEN: Reduce electric consumption as much as possible by implementing every reasonable energy efficiency upgrade available before looking at Solar options. Reduced usage = a smaller, less expensive Solar PV system. Start with fixtures (LED bulbs), upgrade to energy star appliances, replace outdated (read: inefficient) HVAC systems which represent a large portion of annual heating and cooling costs, and also look into insulation and air sealing the structure. Most importantlychange the HUMAN factor: Are the lights on in an empty room? Computers powered up 24/7? Vampire devices always ON? Aggressive thermostat setting year round?
2. Determine PV system size: Once your home or business is as efficient as it can reasonably be, start by tracking the Kilowatt Hours (KWH) usage and monetary costs via utility bills for 18 months (current and prior year). Figure out what the expected annual KWH consumption is, and determine if that is a reasonable marker for the future. Here is the formula for a solar array based on daily need in the Chicagoland climate (*see detailed example below):
PV Array size = ( A / 4.4 ) * ( B / 78% )
‘A’ represents your daily KWH consumption calculated from your annual average, above. ‘B’ is the percent off-grid or the amount you want the system to cover, IE to be 100% off grid use 100%. The value 4.4 is the average solar exposure for Chicagoland as indicated by NREL statistics. 78% is a ‘magic number’ of overall system efficiency, detailed below. *
3. Array Design and Space Limitations: How many solar panels of specific physical dimensions and wattage are required to achieve the KW production from the formula above? Next, determine how much area on a roof, garage, or yard can be allocated to panels and if this space is clear of trees and other obstructions. HINT:Sometimes it can be better to buy a greater number of cheaper panels which produce less per unit provided you have a place to put them.
4. System Design; Inverter Technology: With a plan for panels on a roof (etc.) the next challenge becomes how to collect that power for use. This is the job of the inverter: transforming the DC energy panels provide into AC for the house. The ‘old school’ method connects multiple panels together to form a ‘string’ with only two leads (wires) as the input for a large central inverter. This approach is the least expensive, but also the least efficient. Any shading on one panel limits all panels in the string. Microinverters are the newer technology and are attached to each panel individually. This allows each panel to operate independently of one another, maximizing energy collection under adverse conditions. However, this style also uses special components and wiring which adds cost and complexity. As a middle ground, some inverters (like the SolarEdge brand I chose) allow for optimizers to be installed on each panel (increasing production individually) while the strings are still wired to a single central inverter for the DC to AC conversion. This balanced approach uses standard materials while adding only a moderate total cost and component count to the system.
5. System Design; Mounting, Wiring, and Grounding:Now for smaller but important details. How will the panels be secured to the structure? What is the expense and WEIGHT difference between rail based and non-rail based mounting solutions? Will the structure safely accept the added total load of the panels? Is structural carpentry required? What gauge wire will be necessary to carry the DC current to the inverter? How many strings and what size conduit will be required (remember there are 2 DC leads per string)?HINT: Remember to calculate wire size as expected max DC amperage / 80% as a safety overload factor. Can the DC wiring be added into the building / run to the inverter easily? How far a linear distance is that (voltage drops off as distance increases)? How will the Solar panels be grounded to earth? HINT:Exposed metal in an electrical system (outdoors) needs to be grounded to earth (called a General Equipment Ground) – think lightning protection- so be prepared to adjust the home’s electrical system to accommodate for this.HINT: NEC (code) states a maximum safe operating voltage of 600 VDC. Based on the design, this is important for installer safety! For me the SolarEdge optimizers I chose tune to a max of 500 VDC with a 1VDC safety feature allowing me a safer experience as a self-installer.
6. Other Hardware Options: With the major system components coming together it’s time to pay attention to more minor details. Consider installing both AC and DC shutoff switches (think of a ‘Frankenstein’ lever) outside the building for emergency responders to shut down the system in case of a fire, etc. PLAN TO HIRE A LICENSED ELECTRICIAN to help with installation of the conduit, wiring, switches, inverter, and panels. Does the home need any code compliant retrofitting (earthen ground rod, circuit breaker overloaded, etc.)? Better get that done now; it will be harder to pass electrical inspection with secondary issues looming.
7. Financial Round-Up:Now it’s time to look at the bigger picture. Shop around online and call everyone who sells the hardware you prefer. Request quotes from notable websites and get into the dollar figures with the sales reps. How much will it cost for the panels, inverter/s, mounting, wiring, and professional services (or installation, if applicable)? Don’t be afraid to pick and choose. I was able to save roughly 15% off the initial complete package as quoted by one internet retailer simply by purchasing materials myself. Please consider buying USA made goods. This is probably a once in a lifetime purchase for most of us as most panels carry a 25 year expected lifetime / warranty. I chose Solarworld panels made in the USA. There was an added cost here but I felt it balanced support of my neighbors and fellow citizens with a worldly thing to do. Got contractor friends? See what they would charge for the professional services you may need. Get at least 3 estimates for comparison. Can you afford this outright? Would 30% back from Uncle Sam and maybe 25% back from the State of IL make it easier (or feasible)? Federal incentives may expire in 2016! Search for and apply for any and every state, local, and municipal grant or program related to green energy, Solar, and efficient upgrades to your home. Check out the DSIRE website for incentives and information. Remember the Federal rebates are included in the tax calculations around April. The IL State rebate comes as a check mailed to you after the system is running / completed obligations to the state. HINT:There is a form to fill out to have a Solar system’s value EXCLUDED from the tax base for Cook county property taxes.
8. Plans and Permits:Using the notes and calculations from the above steps, draw up detailed plans for the overall system and use these as documentation to submit to your local municipality to receive the appropriate permit. I showed calculations for wattage and amperage of the AC and DC components, made mockup layouts of the panels on the roof sections, drew a map of the electrical devices and where connections were made, and took pictures of the installation locations for tangible reference. The plan included hiring a carpenter to retrofit attic supports to bear the additional load and hiring an electrician as required by law to install the inverter (you cannot plug stuff into the grid, ComEd & your neighbors won’t like it if you do).
9. ComEd and Net Metering: Presuming your plans were approved, you have a State of IL Notice to Proceed, hardware on order, and you are getting excited; now it’s time to contact ComEd. Why? The State of IL requires utilities to pay you fair market value for any excess generation. The law is referred to as NET METERING. Research it! ComEd has a department for this and in order to interface with the electrical grid your as-of-yet-not-completed Solar PV system will need an Interconnection and Net Metering agreement with the utility. The application/s can be filled out online and it may take a few months for all the paperwork and validation to be completed. Get started on this early, I fudged this a bit and lost some generation credits so please learn from my mistakes!
10. Livening, Monitoring, and RRTP: Once work is completed and inspections passed you can ‘liven’ the system (turn it on, watch it hum). Most manufacturers include some form of internet based monitoring so you can track panel, inverter, and overall system performance. Keep tabs on these metrics for validation with the pending utility bill credits and because watching the graphs of free and clean energy roll in is good fun. A note on real-time pricing: Generally speaking, switching from fixed rate electrical plans to hourly rates for electric supply benefits Solar PV system owners. Why? Because when electricity is most expensive tends to correlate well to hot July afternoons, when the sun is strongest, and thus when the $$ value of PV overproduction is greatest. Conversely the overnight rates are usually very low. Relating to #1 “the Human factor”, shifting your usage habits for things like running dishwashers and laundry machines into the evening hours tends to bias your $$ savings/earning potential even further in your favor when Solar PV is combined with ComEd’s RRTP.
About the author: We try to live as sustainable as is reasonably possible in an urban area. There is a lot you can do: conserve all resources (the Human Factor), choose efficient alternatives, invest in renewable technologies, and focus on simple habitual solutions. We have electric cars supported by the Solar PV system, we garden with water reclamation (rain barrels), and we raise chickens and bees for eggs and honey, and (mostly) make our own bread, butter, yogurt, jam, salsa, pasta sauce, canned goods, and cider. We try to cook as many meals at home as possible using non-GMO, organic, and locally grown ingredients. We agree with the sayings ‘waste not, want not’ and ‘live close to the Earth’; there is, after all, only one.
For a longer version of this article which continues with more details, examples and potential pitfalls, go to our Energy Resources page.