- Overview
- Lots of Shade
- No Racking
- Enphase Advantage
- Fit My Budget
- Flat Roof
Residential Solar Case Studies
For the moment we've put together five case studies of installations that address certain customer needs and three of these have monitoring available to demonstrate the systems power and characteristics.
The tabs on this page correspond to the following:
- Lots of Shade - This is a system in Haddonfield, NJ with some heavy tree cover due south but also to the east and west..
- No Racking - A system with two distinctly different arrays in Washington Township, NJ.
- Enphase Advantage - A traditional system utilizing aluminium racking with with microinverters driven by polycrystalline modules. With three arrays and some structure shade, this system in East Greenwich, NJ just about incorporates everything.
- Fit My Budget - A homeowner doesn't always have to try and offset their entire utility usage and this home in Bridgeton, NJ is the perfect example.
- Flat Roof - Not the normal roof situation for a residential installation, this system in Millville, NJ not only incorporates a ballast system but also deals with shading.
Case Study: Lots of Shade
Location: |
Haddonfield, NJ |  |
System Size |
5,250 watts DC | |
Module Size |
175 watts DC | |
Module Type |
Monocrystalline Black Frame | |
Tilt: |
22 degrees | |
Orientation: |
180 degrees | |
Module: |
Westinghouse Solar | |
Inverter: |
Enphase M-190 | |
Racking: |
Rackless |
Haddonfield is known for its trees and this property was no exeption with heavy tree cover except for an area to the southwest at the driveway. The front yard included two giant ash trees. One ash to the east was removed and the ash to the south was topped on the north side to allow the summer sun to reach the array. The ash continues to provide ample yard shade and the homeowners also do not need to be concerned with the potential in high winds for home damage from large limbs.
One of the challenges in this type of neighborhood is the tree cover that a homeowner can not mitigate because it is on neighboring properties. Often neighbors will cooperate but in certain case such as this home, the tree cover creates the neighborhood ambiance and would be impossible to remove because of its extensiveness. A traditional string inverter would be severly limiting power output in such an installation.
The homeowner opted for a Westinghouse Solar monocrystalline module with a factory attached Enphase MicroInverter. As each module in the system operates independently of the others, shading on one module does not impact the power output of any other module. As can be seen in the 5 minute interval time lapse taken in mid February 2011, most modules are impacted by tree shading during the day and the impact of the large limbs are clear as they walk across the array with the movement of the sun.
Real time information on the operation of this system is shown in the embedded Enphase Enlighten Website at the end of this case study. Each MicroInverter reports back to a monitoring unit connected to the home's broadband that can be accessed locally on the homeowner's computer. Optionally, the monitoring unit can report back production and other statistics to Enphase and be incorporated in the the Enlighten Website that the homeowner can access from anywhere internet is available.
As the sun moves higher in the sky with the summer season, the impact of the front yard ash will disappear, however, shading from the east, southeast and west will still exist during the early moring and late afternoon. This is another advantage of the Enphase MicroInverter as it allows additional energy harvest during those time periods.
In the Solar Pathfinder image to the right, the red outlined area represents the available solar resource for this site. Unostructed sun in the lower center of the diagram is the most valuable. Areas near the top represent the winter months and the sides the sunrise and sunset periods. Normally, if your site receives unobstructed sun from 9 am to 3 pm, it would make sense to install a traditional central inverter system. As visible here, in the months from September to March, the array is impacted by the ash in the front yard and trees to the east. In such a situation, the MicroInverters provide added power during those times and make the system economically viable.
One of the benefits of a rackless system such as Westinghouse is the ability to add landscape rows of modules in the same array as portrait oriented modules. In a system utilizing rails, the modules often need to be positioned with their short axis across the rails making a combination of landscape and portrait modules difficult and sometimes impossible in the same array.
The extent of tree cover to the southwest is evident in this summer photo.
A component of the Westinghouse system is the flashing to which the L foot is attached. The flashing allows water to properly shed the roof.
In this system rows of adjoining portrait modules are supported on a single row of supports.
This is a PSE&G installation as is evident by the meter. The solar load center is populated by two 15 amp breakers, one for each 15 module branch in this 30 module array.
Enphase Enlighten Web Interface
Please spend some time with the Enphase portal. By selecting various time periods you can see the energy production over those periods and also execute time lapse presentations. This is the site's public view and there is no chance of damaging any of the reporting functions. Enjoy!
Case Study: No Racking
Location: |
Sewell, NJ |  |
System Size |
9,975 watts DC | |
Module Size |
175 watts DC | |
Module Type |
Monocrystalline Black Frame | |
Tilt: |
45, 34 degrees | |
Orientation: |
145, 235 degrees | |
Module: |
Westinghouse Solar | |
Inverter: |
Enphase M-190 | |
Racking: |
Rackless |
This home in Washington Township (Sewell) was looking to maximize New Jersey incentives with a system that would look aestetic and have high efficiency. The west rear facing roof was littered with penetrations and with the homeowner's desire to maximize the New Jersey incentive (capped at 10,000 watts DC), a branch of 15 modules was designed into the southeast roof to reach a total system size of 9.975 watts DC.
The two arrays because of their varying tilts and orientations provide a reliable source of power throught the day and the seasons. The southeast roof with its high tilt captures the winter morning and mid day sun, while the southwest roof with a more modest tilt creates more power in the summer months. Original projections anticipated the system would cover over 80% of the homes usage but in the first five months of the system's operation, the home continues to output more to the utility than it has taken in and the homeowners continue to enjoy an electric bill with only a service charge.
This power achievement has been obtained though operation in the winter months including the impact of snow. One of the benefits of MicroInverters beyond harvesting early and late day sun, is their ability to tolerate shade and more importantly in the winter, snow covered panels. Because of the 45 degree slope, the southeast roof clears snow rather quickly. Some snow catches on the space between panels and at the gutterline. Even with the small amount of shading shown for module "a", power output is reduced to less than 10% of the module above it. Similarly, modules "b" and "c" experience similar but less dramatic impact from the snow.
With a traditional string inverter this small amount of shading on the array would have limited the current for the whole array of 15 modules. With MicroInverters, production is at 767 watts for this array but with a string inverter we might expect that power to be only only 230 watts (a third or less). Because string inverters like evenly illuminated modules (even to the point that multiple arrays pointing in different tilts or orientations can not be input into the same inverter), whenever there is shade on a portion of the array, the inverter can not perform its maximum power point tracking effectively and power is dramatically diminished.
Enphase Enlighten Web Interface
Please spend some time with the Enphase portal. By selecting various time periods you can see the energy production over those periods and also execute time lapse presentations. This is the site's public view and there is no chance of damaging any of the reporting functions. Enjoy!
Case Study: Enphase Advantage
Location: |
Mickleton, NJ |  |
System Size |
9,430 watts DC | |
Module Size |
230 watts DC | |
Module Type |
Polycrystalline Silver Frame | |
Tilt: |
26 degrees | |
Orientation: |
150, 240 degrees | |
Module: |
Schott Poly 230 | |
Inverter: |
Enphase M-190 | |
Racking: |
Iron Ridge |
The homeowner at this recently purchased residence was looking to completly offset his electricy usage. By utilizing all three roofs with a polycrystalline module and Enphase Microinverters we were able to create a system that is expected to offset 98% of his estimated annual energy usage.
Small array sizes with different tilts and/or orientations are difficult to string using standard central inverters. With the added impact of structure shading on the small roof faces, microinverters appeared to be the solution. Although a central inverter could have been used on the larger array since late afternoon shading was limited to the winter months, the homeowner after reviewing independently the performace characteristics of the Enphase MicroInverters opted to have the entire array be powered using the Enphase units.
With the 2010-2011 winter season including some significant snowfall, this system was able to continue to produce power even with partial coverage of each array.
Enphase Enlighten Web Interface
Please spend some time with the Enphase portal. By selecting various time periods you can see the energy production over those periods and also execute time lapse presentations. This is the site's public view and there is no chance of damaging any of the reporting functions. Enjoy!
Case Study: Fit My Budget
Location: |
Bridgeton, NJ |  |
System Size |
4,860 watts DC | |
Module Size |
180 watts DC | |
Module Type |
Monocrystalline Black Frame | |
Tilt: |
14 degrees | |
Orientation: |
158 degrees | |
Module: |
Canadian Solar | |
Inverter: |
Fronius 5100 | |
Racking: |
Conergy |
In this case, the homeowner wanted a system to fit their budget. Although the system would only cover less than 50% of their electrical usage, between the utility purchases saved and the SREC proceeds, the system was economically viable.
Case Study: Flat Roof
Location: |
Millville, NJ |  |
System Size |
6,475 watts DC | |
Module Size |
175 watts DC | |
Module Type |
Monocrystalline Black Frame | |
Tilt: |
8, 12, 43 degrees | |
Orientation: |
193 degrees | |
Module: |
Westinghouse Solar | |
Inverter: |
Enphase M-190 | |
Racking: |
Rackless, Stancion, and Ballast |
With three distinctly different roof types and significant initial shading, this project was definitely a design challenge. We're pulling together the additional photos for this page and will be adding them shortly.
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To schedule a site visit and receive a free quote please give us a call at 856-468-2355, e-mail us at sales@onpeaksolar.com, or complete the contact form below. A representative will contact you to provide information and perform an evaluation over the phone to determine whether you're a candidate to Go Solar.