Gone Solar—a One-Year Retrospective*

by Axel Schmetzke

*For a PDF version of this article click here. A similar version of this article was originally published in HOOPLA (Central Wisconsin), February 1013, pages 14-16.  

Flashback to December 3, 2011. Two months of planning and agonizing over various decisions is about to bear fruit.  The crew from Northwind Renewable Energy, a company servicing central Wisconsin, just installed the last of 14 photovoltaic solar panels on the roof of the Schmetzke/Nelson residence in Stevens Point. Wahooo! With the flick of the newly added breaker in the main distribution panel, the house is going solar. The weather is dismal. Low, dense cloud coverage does not bode well for this first day. Yet, with all electric gadgets and appliances turned off, even the meager 100 watts of power generated causes the wheel in the electric meter to spin backward, ever so slightly. The system works, but will it live up to my hopes and expectations?

The decision to invest in solar energy had emerged gradually. Travelling through Germany every two years, I had been witnessing an alternative-energy boom that is unprecedented in the world. Criss-crossing the country by train, I saw a tremendous growth of the number of wind generators and solar installations over the past decade. Instrumental was the Renewable Energy Act adopted by the German government in 2000, which guarantees operators of renewable energy systems lucrative long-term rates for the electricity fed into the power grid. Between 2000 and 2011, photovoltaic (PV) power production alone increased from .064 TWh (Terawatt-hours) to 19.3 TWh, a 3,000% increase. According to estimates, 6% of Germany's total electricity consumption is currently met by PV installations.

Anyone traveling through the US will quickly find that PV installations have not established a significant foothold in this country. (For comparative statistics, see Zachary Shahan's article on Top Solar Power Countries.) A year ago, I travelled some 350 miles by train through the nation’s Sunshine State. From Miami to Jacksonville, I did not notice a single PV installation. Why has PV electricity generation not made any significant inroads even in one of the sunniest states? Granted, with 25 Euro cents (32 US cents) per KWh, Germany's electricity is far more expensive to begin with, which makes PV systems more economically viable in that country, but are there not incentives for alternative energy in place here in the US that encourages the installation of PV systems? Specifically, what is the situation here in Wisconsin? If I wanted to generate the bulk of electricity consumed in my household with a PV system, would there be sufficient space on the south-facing side of the roof? How much would it cost? How many years would it take to recoup the initial investment? It was clear to me that I wanted to go with a grid-tie system, which would draw from the power grid when solar production is low and feeds into it when production is high. This would avoid all the costs and headaches associated with purchasing and maintaining a large battery bank.

Two days of online research, along with the information found on my monthly utility bills, provided me with the answers. Looking at the past three years, my annual electricity consumption averaged 4,683 KWh. At a rate of 12.2 cents per KWh, this amounts to a yearly cost of $572. In order to figure the size of the system needed to meet this demand in Wisconsin, specifically a system to be installed on my largely unshaded south-facing roof with a 22-degree slope, the PVWatts Calculator (http://www.nrel.gov/rredc/pvwatts/) was extremely useful.  Its use is straight forward. After entering some basic data, such as nominal system size, tilt angle, orientation of the roof, and local energy cost, it provides a projection of month-by-month output figures and their associated energy values. By playing around with various system sizes, I established that a system rated for 3.5 KW (DC) would be the best fit for my household. Fourteen 250-watt PV panels, or modules as they are often called, each 66” by 39” in size, would do; and there would be sufficient room for them on the south side of my roof.

 Solar panels on the roof of the Schmetzke/Nelson residence.

Solar panels on the roof of the Schmetzke/Nelson residence.


Having established the system size, several other decisions had to be made:  Shall I install the system myself or hire professionals to do the job? Which specific panels shall I purchase? What types of DC-to-AC inverters shall I select?

After some online price checking, I figured I could purchase all the parts, including panels, mounting hardware, wiring, and inverters, for about $11,500. At age 57, the prospect of climbing a 28-foot ladder and moving about on my sloped roof, carrying heavy and bulky components, was not an appealing thought.  And while figuring out the technical details would not have been beyond my capabilities, it would have required a lot of time. After negotiating with the friendly folks at Northwind, I accepted their offer to provide a turnkey system for $17,000, provided that I string some of the indoor wires. Preferring products made close to home (as opposed to China), I opted for panels manufactured by Helios in Milwaukee and DC-to-AC microinverters, a fairly new product, by Enphase, a California-based company.

 Display of panel-by-panel output utilizing Enphase’s Enlighten system. The panel on the

Display of panel-by-panel output utilizing Enphase’s Enlighten system. The panel on the upper right is partially covered by snow.


Older installations change the DC electricity produced by the panels into AC by means of one large central inverter. One of the disadvantages of a central inverter system is that several panels are wired in series, in one string, and when one panel gets compromised by electrical failure, leaves, bird poop, or snow, the total output of this string is affected. In a microinverter system, the DC-to-AC inversion is done for each individual panel. Problems with one panel do not affect the performance of the other panels, and with the additional help of a product called Enlighten, also by Enphase, the output of each individual module can be monitored through the Web. Real-time panel-by-panel output of the system at the Schmetzke/Nelson residence can be seen at https://enlighten.enphaseenergy.com/public/systems/xrYk44179.

The $17,000 was not my out-of-pocket expense. Until 2016, the US government offers a 30% tax credit for installations like this, and back in 2011, the Wisconsin Focus-on-Energy program offered a rebate for up to 30%. The exact figure depended on specific site conditions, such as shading. In my case, out-of-pocket expenses amounted to $7,200. With anticipated annual electricity savings of $459, it will take me some 15.5 years to recoup my initial investment, not considering any of the following factors: changes in residential electricity rates, which have gone up at an annual national average of 5.5% over the past 40 years; the increase in house value , which in Wisconsin will not affect the assessed value; the forfeited potential gain from investing the money elsewhere; future increases in roof replacement expenses; and the gradual degradation of the modules’ efficiency, which is estimated to be around 1% per year.

 Output on a sunny day in late December.

Output on a sunny day in late December.


The Wisconsin Focus-on-Energy program has been rolled back. Rebates are now limited to $600 per KWDC-rated capacity, up to a maximum of $2,400. Had I not met the end-of-2011 deadline, my out-of-pocket expense would have been $10,100, and the break-even recoup period would have lengthened to 22 years.

Now that the system has been operating for a year, the time is right for a first evaluation. Has the system lived up to my expectations? A look at the new utility meter that had been installed shortly after the PV system went online revealed that it had actually run backward. This is a clear indication that the energy produced by the PV system over the course of the year exceeded that of the electricity consumed in the house.



Past draw from grid (average)

Projected draw from (feed into) grid

Actual 2012 draw from (feed into) grid



































































































Table:  Past, projected and actual power consumption/production balance for the 3.5KW (DC) system at the

Schmetzke/Nelson residence.


The figures for 2012 provided with the monthly utility bills complement the meter reading. While initial projections suggested that close to 600 KWh would have to be purchased over the course of the year, at a cost of $113, the system produced so much that 768KWh were sold back to the Wisconsin Public Service Corporation (WPS). Because this utility company establishes consumption-production balances on a monthly basis, and because it only pays some 3 cents per KWh fed into the grid, not much “profit” resulted from this surplus. Nonetheless, instead of paying $113 as projected, only $6 had to be paid to WPS, and instead of the anticipated $459, $566 in electricity costs were saved in 2012.

The figures provided by the Enlighten monitoring system showed that 4,800 KWh had been produced, about 700 KWh more than projected. If coal, oil, gas, or wood had been used instead, roughly 3.3 tons of carbon would have been released into the atmosphere.

The system clearly exceeded expectations. In parts, this may have been due to the conservative estimates on which the projections were based, but it was probably also the result of a particularly sunny year. Data provided by the National Weather Service for the Wausau region indicate that 2012 was the second warmest year on record and that the number of fair days exceeded those in the previous three years.

No matter what the cause for this exceptional performance might be, the system clearly works. I have no reason to regret the decision to have PV solar panels installed on my roof. The carbon footprint at the Schmetzke/Nelson residence has been significantly reduced, and any lingering doubts about the system’s economic viability have been put to rest. Naysayers may belittle the efforts made by individual house owners to invest into photovoltaic technology, calling it uneconomic and unfeasible on a large scale. My own experience points in the opposite direction. In an economic climate where most investments either provide little return or carry significant risk, why not invest your money for a modest return at low risk into a technology that helps this world become a cleaner and ecologically healthier place?



About the author

Axel Schmetzke

Axel Schmetzke is a librarian at UWSP. Previously, he earned his living as a college instructor, a disabilities professional, and a special education teacher. Most known for his research and advocacy regarding online accessibility for people with disabilities, he occasionally ventures into completely different areas, such as his investigation into the life and works of Hugo Rheinhold, a late-19th century German-Jewish sculptor. Axel collects old radios and radio tubes. So, if you have any, don’t throw them out.

First version: February 5, 2013. Last updated: Thursday February 07, 2013