If you look at a map that shows how much solar energy is available at different locations in the United States, you can't help that notice that Pennsylvania is one of the cloudiest spots in the country. Granted, the southeast corner of the state is a little bit sunnier, but there's no getting around the fact that we get more than our fair share of clouds.
One positive benefit of this is that we are usually blessed with ample rains throughout the year that allow for most farms to avoid costly irrigation. One down side is that solar power struggles to be cost effective in this region. The US Department of Energy's National Renewable Energy Laboratory published an analysis that predicts that the payback for solar photovoltaics in the Keystone State can be as high as 60 years or more. This is not a very good scenario for a business investment.
However, in recent years, many farmers and others have installed solar photovoltaic panels on their properties, and have begun generating their own electricity. Why? Well, the bottom line is that people really like photovoltaic (PV) electricity for a variety of reasons, and as a result our government is putting a lot of tax dollars towards making it more affordable to install PV. This can come in the form of government grants, tax credits, and government mandated "alternative energy credits", to name a few. As a result, some projects have had as much as 70% of their installation cost covered by government programs - under those conditions solar PV almost makes economic sense.
Of course, there are non-monetary reasons to install PV as well, including the simple fact that it's fun to generate electricity, and even more fun to not have to pay a monthly electric bill. Solar PV is generally very low maintenance, and it tends to work without owners having to constantly check and fiddle with the system.
So, if you are thinking that a Solar PV system might be in your future, what kind of things should you think about?
1. Where would you put it?
The ideal location for a stationary PV array is a south facing surface that is tilted at an angle equal to the latitude of your location (in Pennsylvania, that's about 40 degrees up from horizontal). However, you don't have to have the perfect slope or orientation to get good performance. For example, if you have a barn roof that faces within about 20 degrees of south, and has a bit of slope on it, you'll probably be fine using that roof as a location for a photovoltaic array.
2. Will it stay in place?
There are few things as embarrassing as having your solar panel blow away in the wind, or worse yet, having the weight of the panels squash your barn. Most solar panels are surprisingly light, so little or no structural stiffening is needed to make most barns “solar-ready". However, if your building is on the rickety side, you should have it checked by a qualified engineer. Most installers are experienced with using good quality mounting hardware that not only holds the panels down, but prevents roof leaks as well.
3. What about the wiring?
The electricity generated by a photovoltaic panel is "Direct Current" (DC). You need to change it to "Alternating Current" (AC) with a device called an "Inverter" before it can be fed into your farm's power system. (Footnote: a few folks use the DC power directly rather than switching it to AC, but that is not really common in Pennsylvania). You will need a spot on your farm to install this equipment, preferably close to your solar panels and near the main distribution panel for your farm's electrical system. Some inverters can be installed outdoors, but it is always nice if they can be kept under cover. Safety shutoff switches and lightning protection are also essential elements of the overall system.
4. Can you afford it?
The payoff for solar PV electricity depends on the future price of electricity as well as alternative energy credits. Both of these are highly uncertain. Right now, the credit market is taking a beating in Pennsylvania, but it is sure to rebound. However, nobody really knows what the long term value of those credits will be. Regardless, you should take a close look at the financial side of things and be absolutely certain that, if there is a bad year or two in the credit market, you will be able to get by.
Finally, be sure to talk to people - check with more than one installer, and talk to as many farmers in the area that you can find who have already installed solar PV. That will probably give you the best idea of whether or not a solar power system would make sense for your farm.
----- Daniel Ciolkosz, Penn State Extension, Department of Agricultural & Biological Engineering University Park, PA