How to Install Solar Power on Your Roof (or Backyard)

Solar Energy (both photovoltaic and solar hot water, aka solar thermal) are great resources to have at your disposal. In the case of photovoltaic, you can substitute the power from your utility grid by harnessing the sun’s power and converting the sun’s rays into electricity. With rising electricity prices, photovoltaics (aka solar electric) is a great hedge against ever expanding utility bills. The photovoltaic industry is growing by leaps and bounds. You may want to get into the action.

How? In a previous post, I went through the steps of picking a solar installer. What we are reviewing today is whether solar is right for you. Most homes are in a position to build some form of solar power. You can get over the whole aesthetic obstacle – as you will see when you have your shiny brand new solar electric system on your roof, your neighbors will stop by and inquire – what is this – how does it work. Forget the iPad, you will be the coolest person in town with 5,000 watts of DC Power pumping from the sun to your home.

So let’s focus on what makes solar a right fit for your home or business. First, it is good to lay out what you are trying to achieve. The sun shines everywhere (even in my hometown of Rochester, NY), but you want to make sure your solar electric system maximizes the sun’s potential given the situation. In order to do this, you want to put the system in a place on your property that will receive the most sunlight. The roof is always a good starting point but if you have the land, a ground mount is also an option. The goal is to reduce any losses you may suffer from less than ideal conditions. The three major factors that must be taken into account are 1) Orientation to the sun – South facing direction; 2) Tilt – Angle of the panels; and 3) Shading – Any obstacles or trees that block your system from the sun.

1) Orientation to the sun – South facing

As we know the sun rises in the east and sets in the west. For those of us in the northern hemisphere, the sun travels that east-west path south of us for much of the year. For this reason, you would like the solar energy system to face true south (which is actually magnetic southwest – you will have to grant me this one – the explanation for the variance between true and magnetic south is a discussion best suited for a large jug of red bull and a strong willingness to understand so we can leave that for another day). The other two major factors are the tilt of the solar panels (also facing south) and the shading.

Most buildings do not have a roof that faces exactly true south so if you have a pitched (or angle roof), then you would choose the roof areas that face south. Flat roofs have more flexibility because you can face the system in the direction of your choosing.

2) Tilt – Angle of the panels

Now that you have found which roof area(s) are south facing , the next factor is tilt. If you have a pitched roof then it is always structurally sound to build the system at the same angle as the roof. Because the earth is on its own tilt as it revolves around the sun, the ideal tilt is based on your latitude. In my region of New York, New Jersey and Pennsylvania, the latitude ranges from 40-41 degrees north of the equator. Therefore the ideal tilt in an unshaded area would be about 40 degrees. Note I qualify this by saying unshaded area – if shading is an issue, then you may be better off with a lower degree tilt such as 30 degrees so as to avoid obstructions from blocking the system in the winter months. As with each solar energy system, it is situational and your installer must work to build the system that is custom to your home. Even though tilt does play a major role, there is not a huge variation in output from a 10 degree tilt and a 70 degree tilt. So in the case of a pitched roof, it is usually advisable from a structural perspective to build the system so that is at the same angle of the roof. By putting it inline with the roof, you are reducing the influence of wind as a factor and also making for a better aesthetic.

For flat roofs, your installer will recommend a tilt and array layout that will maximize the amount of panels while avoiding any shading from one row of panels to the row behind it.

3) Shading – Obstacles blocking the sun

Ahh, shading – beautiful trees in the way. Trees can be all over your property just as long as they are not high enough to block the system during the peak hours of 9 AM and 3 PM. In fact, my company SunBlue Energy just built a solar energy system in the woods of Pennsylvania. Tree cutting was necessary in order to remove obstacles to the sun, but the system is still surrounded by a whole forest of trees and is producing at a very strong rate. Your installer will let you know if there is any tree trimming needed. Remember, all trees to the north of the system are safe. Not all trees in the south are going to be in the way because your roof tilt or orientation to the sun. And the most important thing to have in your memory box is how many acres of trees your solar system will be saving by not relying on fossil fuels.

Solar energy is always worth looking into. Never rule yourself out based on what you think may or may not influence the power output. You can utilize the info about the above major factors when working with your installer to make sure solar is a right fit for you home or business.

photo: muenzer