Our heads up battle!
Ah, the question I get asked all the time: “Tyler, why are you recommending solar panels when everyone is putting up wind turbines?” There are a lot of misconceptions about wind and solar so I thought I would address some of those in this article.
First, this post is specifically designed to address systems located in Southern Iowa and much of the surrounding area. In areas with higher wind speeds and/or higher solar irradiance, the economics I am about to outline will be quite different. Also, this article will not address utility scale wind turbines (2.5 MW+). This is specifically a comparison of solar panels to small scale wind turbines for small businesses, homes, farms, etc.
Solar: For standard arrays with a grid-tie inverter or micro inverters (i.e. those without battery backup), there is very little maintenance. On an annual basis, you should check connections, tighten bolts, clean the panels, etc. But honestly, if you are lazy with your maintenance, you probably aren't going to have many problems. The advantage to solar is the fact that there are no moving parts. The sun shines on the solar cells and it produces an electrical current; it’s as simple as that.
Wind: Maintenance on a wind turbine varies greatly from manufacturer to manufacturer. For example, direct drive turbines requires very little maintenance because there are only a few moving parts. On the other hand, some turbines have a gearbox which requires annual maintenance. In either case, the manufacturer includes an annual maintenance schedule in their owners manual.
Solar: Solar panels can more or less be mounted anywhere and they will produce power; as long as they are facing the sun. You can mount them on the roof of a building, on the ground, on the side of a building, on the side of a pole, wherever; there are infinite mounting options for solar panels.
Wind: Wind turbines, at a minimum, need to be mounted 30 feet above anything within 500 feet. This presents a problem when you live in an urban environment or near trees. There are typically ordinances in place for maximum structure heights. But mainly, they just don't work in town because there are too many objects that block the wind. Yes, I know, it seems windy in town, but it doesn't even come close to the amount of wind outside of town when you look at annual averages.
More Predictable Energy Output
Solar: When I am calculating the estimated energy production of a solar array, I can safely use the same daily average for almost the entire state of Iowa. There is a slight difference when you get into the northern part of the state but the average is still relatively close. Since solar irradiance is so predictable, the inherent risk of the system is significantly lower than that of a wind turbine due to the fact that there are fewer variables.
Wind: Average wind speeds at a location are much more complex as there are many variables. You have to take into account all of your surrounds (trees, buildings, terrain, etc) and make an educated guess as to what the average will be. For example, you may have a 12 mph average wind speed in one location and then only average 8 mph half a mile down the road. If the wind turbine is not sited properly, you may not realize the return on investment that you expected.
Warranties & Design Life
Solar: Most of the manufacturers with good quality equipment warranty their solar modules for 25 years. The warranty on inverters varies greatly but typically they range from 10 - 25 years. Most of the inverters we sell come with 25 year warranties. The design life of a solar array is 30 - 40 years (even considering minimal maintenance). Be careful though, you should take the company’s history into account when looking at warranties. If the company has a long history in the solar industry, chances are they are high on the bankability index. Bankability is essentially a measurement of the likelihood that the manufacturer will be around in 25 years to honor their warranty.
Wind: Most wind turbine manufacturer’s warranty their turbines and inverters for 5 - 10 years. However, you can typically purchase an extended warranty. The design life of a wind turbine varies between manufacturers but typically they estimate 20 - 25 years (some claim up to 40 years). Annual maintenance will be required to maximize the life expectancy of the turbine.
Solar: Solar panels are silent during operation.
Wind: At higher wind speeds, its not uncommon for small wind turbines to operate in the 90 - 100 dB range. As a reference, a lawn mower operates around 100 dB.
Lower Cost Per kWh Produced
Below, I will compare the net system cost of a solar array and a wind turbine, both with an annual energy output of 16,500 kWh.
Solar: 44 solar panels will produce 16,500 kWh annually. The gross system cost is approximately $39,000. After tax credits and depreciation (commercial systems only), the net system cost is $8,700.
Wind: A 10 kW wind turbine in an area with decent wind exposure (12 mph) will produce 16,500 kWh. The gross installed cost of the system is around $55,000. After tax credits and depreciation (commercial systems only), the net system cost is $22,137
Solar has a $16,000 lower upfront cost (29% reduction) and a 61% reduction overall.
As you can see, solar is the obvious choice on a small scale and has many advantages. Wind only starts to make economic sense when you look at it from a utility scale. From maintenance and noise to warranties and economics, solar wins in every category. Please contact us if you have any questions.