Solar PV Array: Orientation and Tilt

A common misconception when it comes to the placement of your solar PV panels is that you can put them anywhere that there is sun light. While it is true that a solar panel will generate electricity when there is sun light, the amount of electricity can vary greatly based on its tilt and orientation. 

Orientation:

In the northern hemisphere the general rule of thumb is that, when possible, you should face your panels "true" south. When using a compass it will point you to magnetic south. True south is about 14° west of magnetic south in CT. So if you are purchasing/ building a ground mounted solar array you will want to make sure that it is facing true south. 

Tilt:

Once you have the proper orientation the next step would be to determine the optimal tilt. A panel will produce most effectively when it is perpendicular to the sun. The suns elevation changes throughout the year so you should take the average elevation/ the latitude for your arrays specific location to use as the tilt. Something to keep in mind is that you may be limited to the engineering specifications. Here in CT we have winds that cause most ground mounted arrays to be restricted to a tilt of ~35° or less. In this case you should tilt the array to that 35° when possible. 

Example: The following will be based on a project in CT at a 41° lattitude

We have a project in New Milford CT that is a top-of-pole mounted solar array. With this type of mount you are able to adjust the tilt of the panels.

The array was installed facing south/ south-west (as seen from Google maps screen shot below). In some cases true south isn't always the best option because of shading or obstructions. For this particular site we adjusted the orientation to avoid shading. 

With this design you are given six different tilt options:

As previously mentioned, our engineers recommend a tilt no greater than
35° for a ground mounted array in CT.

Now that you have installed an array facing true south with the ability to adjust the tilt, the next question is: When and how often should we change the tilt?

We'll first start with how often. Compared to an array that is constantly following the sun (solar tracker) a fixed tilt array will collect approximately 71% of the available energy (assuming ideal conditions). An adjustable array which you change twice a year will yield approximately 75.2%. Finally, if you were to adjust the array four times a year, or every season, you will be able to collect approximately 75.7% of the available sun. 

Given the small benefit increase of changing the tilt more than twice a year we recommend adjusting your array once in the spring in once in the fall. The best dates for a project in CT would be around March 30th and September 12th. 

For this specific project we recommend the 15° setting starting at the end of March through early September. For the fall and winter we recommend no greater than the 35°, again because of engineering loads. 

Solar Fun Fact with Chris

Solar Fun Fact with Greg

Monocrystalline vs. Polycrystalline: Which Solar Panel Is Right For Your Project

If you've been looking into investing in solar PV to help reduce your electricity bills or help the environement you have likely come across two common types of panels, monocrystalline and polycrystalline. We're going to briefly explain the difference and help guide you in your selection.

 

Monocrystalline

Monocrystalline solar panels are made with a single layer of silicon during the Czochralski method. They have a higher efficiency than polycrystalline panels and therefore do better in low light environments. When compared to a polycrystalline panel of the same same size, they are able to create a larger amount of energy out of the same footprint making them a better option for people looking to get as much energy as they can from a limited amount of space.

Polycrystalline

As the name implies polycrystalline panels are comprised of multiple silicon crystals. The processes used in making these panels is both quicker and less expensive to manufacture which translates to a lower cost to the consumer. However, the polycrystalline panels are less efficient than their mono counter parts. In order to get the same amount of energy as monocrystalline panels they would need a larger footprint. If you have a large amount of unobstructed roof space or land that is not being used these slightly lower priced panels may be a better option.

Farms Progressing with Solar

When people think of solar panels, more often than not, they think of them on residential roofs or maybe even spanning large commercial buildings. But with the cost of electricity going up there are other, less obvious structures that are incorporating solar electric systems. Century old farms are beginning to look for an alternative energy source which is both cost effective and safe for the environment.

This has led a number of local Connecticut farms to install solar electric systems on their property. While ground mounts are often a popular choice, some are choosing to use their existing barns as a way to progress with modern technology, without interfering with the valuable land they use to grow crops and feed their livestock. The Hickories of Ridgefield is an organic farm in Ridgefield, CT that has been growing crops for over 2 centuries. They decided they wanted to decrease their carbon foot print as well as their electricity bills and asked PurePoint Energy to make that happen. The end result was a 52 panel, 10.66kW solar array on their west facing barn. Stone Wall Dairy, another organic farm, decided they too wanted a way to offset their electricity usage and felt that solar technology was the way to go. PurePoint Energy designed and installed a 48 panel 10.56kW solar electric system on the barn roof.
Both systems provided a maintenance free, clean energy solution that was cost effective. They were able to take advantage of the available state and federal incentives making this investment decision a no-brainer. These farms will hopefully be the begging of a long list of farms that continue progressing by combining their historical infrastructure with modern technology to help both the agricultural industry as well as the environment.

New Building-Integrated PV: Solar Windows

Skyscrapers like Chicago’s Willis Tower consume huge amounts of energy but have so far been unable to install solar panels because of the comparably small amount of roof space they have. However, solar technology company Pythagoras Solar has now found a way of using the massive amount of sunlight that hits the tall building walls every day.

Pythagoras’s new solar windows are now being tested on a few buildings, including the Willis Tower. The product is the world’s first transparent photovoltaic glass unit, and is used in place of regular windows, which do nothing to offset energy use. The typical window is also a huge burden in the summer; all offices want natural lighting, but that invites more heat for which we then need more air conditioning. The solar window allows light to come in, but can also use it to generate electricity, all in the same product. The panel, like traditional solar panels, still has grids on it, but they resemble a set of open venetian blinds. Other than that, it is also clear, just like an ordinary window. Its silicon PV cells sit between two panes of glass.

Pythagoras Solar’s new product combines the ideas behind self-tinting windows and thin film solar windows, which also tried to control the amount of light let in and generate power. The added aesthetic value of not actually looking like solar panels makes the product more attractive to architects and homeowners, as well. Prices have not been revealed yet, so interested residential customers may have to wait to install them. However, Founder and CEO Gonen Fink estimates that the typical consumer will recoup the cost of the windows after three to five years.

The unit, which has already won GE’s Ecomagination Challenge, joins other BIPV products like solar shingles and solar façade modules in using buildings themselves to generate energy.

With SB1 passed, what has been implemented? Great incentives for CT!

The Clean Energy Finance and Investment Authority (CEFIA) is going to be offering a residential solar incentive program which aims to build at least 30 megawatts of solar by 2023. A third of their funds, which is $10 million dollars a year, will now be used toward this new program. CEFIA can structure this incentive in two ways, as an upfront rebate or as performance-based incentives. As funding diminishes over time, so must the incentives and CEFIA plans to keep us updated on the status of their budget via their website.

Taking effect on January 1, 2012 the electric utilities must solicit 15 year contracts with developers for zero-emission Class I renewable energy credits for non-emitting Class I renewable energy technologies such as wind, solar, and micro-hydropower. The budget for this program starts at $8 million per year and will go up to $48 million a year by 2018. These projects must be customer-sited and less than 1 megawatt in size. This project will make it possible for municipalities to install far more solar power than ever before on town buildings and schools, and will be benefit those interested in powering town facilities with wind.

A reform has also been made to the CT Energy Efficiency Fund. The electric and natural gas utilities have been removed as voting members of the Efficiency Fund board, although they are still kept as paid program administrators. The Department of Energy and Environmental Protection’s commissioner/designee is now the chair of the Efficiency Fund’s board. This change in the CT Energy Efficiency Fund board will allow the fund to be more transparent and responsive to outside input.