The size of a solar electric system is often described in Watts (W) or kilowatts (kW). One kW = 1,000 W. Watts are a unit of power, just like the horsepower of an engine. They express the maximum possible output of energy the system can produce at any point in time. When sunlight strikes solar electric panels, they produce electricity that is measured in kilowatt hours (kWh). Kilowatt hours are the units of energy you buy from your utility and use in your home to run your appliances, lighting and electronics.

There are a number of considerations about your roof that your installer will discuss with you when evaluating a solar system. These include:

• Age: Generally speaking, it is advised that your roof be 10 years old or less before going solar. The reason is that if you need to replace your roof just a few years after going solar, you will need to take the panels off before it can be resurfaced, which adds cost. In cases of older roofs, it is generally recommended that you replace your roof at the same time as going solar, which can reduce costs. However, the 10-year rule is not hard and fast. For example, if you purchase a solar system raised on a canopy, then it may be possible for your roof to be resurfaced without moving the panels. If you have an older roof, we recommend that you discuss your options with your Installer Partner.
• Condition: If your roof has been leaking or is generally in rough shape, it is generally recommended that you fix it before going solar. This is for the same reasons as replacing an older roof listed above. If you are going to have to repair your roof soon, you don’t want to have to move the solar panels to do so. Also, your installer's architect or engineer will need to certify that the roof can structurally support solar.
• Space and obstructions: A big reason why solar generally costs more in places like Brooklyn than the suburbs is available roof space. Brownstown roofs tend to be smaller, and flat roofs also require 6-foot wide access pathways for the Fire Department in case of emergencies. These fire clear paths must go from the front of the building to the back and side to side, which can reduce the available space by almost 50 percent on smaller roofs. Additionally, obstructions such as skylights, vents, and hatches cannot have solar installed over top of them and require additional clearance space around them by the Fire Department. If you have a small roof with limited space, all is not lost. One option is to use higher efficiency panels that maximize the solar energy production you can get in the limited space, and another is to utilize a canopy racking system. The canopy will raise the panels 9 feet above the roof, which allows the Fire Department access pathways and other obstructions to legally go underneath, according to the code. The canopy solution may be limited in Historic Districts, however, because panels cannot be visible from the street level.
• Shading: Shading is a big factor in a roof’s viability for solar. Although your roof may look sunny most of the time, even a building a block away may shade it too much for solar to be viable if the building is large and tall enough. Installers will model the amount of sunlight that hits your roof throughout the entire year using satellite imagery and 3D modeling software. This allows them to project the optimal placement of solar panels on the roof, how much energy the solar panels will produce, and what the resulting payback will be. You may be surprised just how much shade your roof gets – even the flues between your building and your neighbors cast shadows – but you won’t know for sure until you have an assessment (generally they are free). If you have a building that is taller directly next door or a large tree, particularly to the south, this is generally a problem. Raising the solar panels on a canopy can help in some instances, but shade from an adjacent building is the most likely reason your roof would be considered definitely non viable.

Solar panels have no moving parts, which makes them very durable. As a result, there is essentially no maintenance required, as noted above. The solar contractors generate their electricity production and savings projections using historical weather data to account for days when the panels will not produce due to snow cover. As a result, snow should not impact your payback.

In terms of cost, the lack of maintenance required for solar means there is also very little cost. Should something go wrong, components will be covered so long as they are under warranty. The panels are warrantied for their electric production for 25 years. Microinverters and DC Optimizers, which are offered by installers, are also warrantied for 25 years. Should you choose to utilize a string inverter rather than one of these solutions, the inverter would likely require replacement after 10-12 years.

Yes, just not as much. Under an overcast sky, panels will generate less electricity than they produce on a clear, sunny day.

Solar electric systems require very little maintenance. Rain showers will generally take care of the pollen and dust that fall on your solar panels. If your system is shaded by trees, you may have to trim and maintain branches to protect your system from falling limbs, and to minimize shading and maximize production. During extremely snowy winters, you may have to clear snow from your roof to protect your solar panels and maximize winter energy production. It is important to note that snow will melt off of a tilted system, except when there is an extremely heavy snow or prolonged freezing temperatures. To clean snow, homeowners are cautioned to use a tool specially designed for solar panels that has a soft working surface, because metal or other hard surfaces can damage the panels.

The payback period is the amount of time in years that it takes for a solar investment to pay for itself. Payback times are typically referenced in the context of systems purchased with cash because leases and financing loans are available for $0 down meaning that they have a 0-year “payback” – you see savings immediately!

For cash-purchased systems, the payback time depends on the size and cost of the system. Solar will offset any cost on your electric bill measured in kWh, including supply and delivery. For example, Con Edison rates average about $0.25/kWh, so you save this much with each kWh your solar panels generate. A typical 5kW system generates about 6,200 kWh per year, meaning you could save $1,550 annually. Given that these systems cost $6,800-$7,300 after incentives with base solarize pricing, it’s easy to see how they can pay for themselves in just 4-5 years. In cases where more expensive canopy racking is required, paybacks are still frequently between 5-7 years because the canopies allow for more solar to be installed and this extra generation capacity offsets the higher costs.

Your solar savings depend on the size of the system you choose, your annual electrical usage, electricity rates and any financing option that you choose. To start, enter your address into the NY Solar Map and click on your rooftop or use the draw feature to outline a potential installation. The calculator on the map  will feature your estimates on the bottom half of the screen.

Yes. You will receive a monthly bill from your utility company as you always have, but the amount owed will differ depending on your monthly electrical usage. Depending on how your system is sized, you may accrue credits in the more productive summer months, which can be carried over and used in the less productive winter months. This process, similar to rollover minutes on a cell phone plan, is called “net metering.” For more information, see Sustainable CUNY’s Residential Net Metering FAQ and Commercial Net Metering FAQ.

If you use less than roughly 350kWh per month or spend less than $98 per month electric bills, it is unlikely your solar array will have an attractive return on investment. The reason is that regulations limit the size of your system to 110% of your annual electricity usage. Electrical usage this low would only allow for a very small system, and due to the fixed costs of solar (e.g. permitting costs, design costs), the cost would be high relative to the potential return from electricity savings. This results in a longer payback time. If your electricity usage is this low, you could still consider solar for its sustainability impact rather than its return on investment.

Without a battery backup, grid-tied solar electric systems won’t operate when the power goes out. You can add a battery backup to your solar panels to keep the lights on during a blackout. Typically battery backups costs range from $5,000- $15,000. Backup batteries are generally sized to meet your critical electric needs.

Solar electric systems require very little maintenance. Rain showers will generally take care of the pollen and dust that fall on your solar panels. If your system is shaded by trees, you may have to trim and maintain branches to protect your system from falling limbs, and to minimize shading and maximize production. During extremely snowy winters, you may have to clear snow from your roof to protect your solar panels and maximize winter energy production. It is important to note that snow will melt off of a tilted system, except when there is an extremely heavy snow or prolonged freezing temperatures. To clean snow, homeowners are cautioned to use a tool specially designed for solar panels that has a soft working surface, because metal or other hard surfaces can damage the panels.

Step by Step

1. Evaluate your properties' solar potential (see the NY Solar Map solar potential calculator)
   
   
2. Check eligibility for solar incentives
   
   
3. Gather energy bills and contact solar installers: this option is available on the NY Solar Map once you have viewed your properties potential.
   
   
4. Receive remote and on-site evaluations from contractors to get at least 3 quotes
   
   
5. Check with your installer to see if your roof needs to be reinforced or replaced
   
   
6. Contact references from solar contractors
   
   
7. Evaluate costs and financing options to decide on direct ownership or third-party ownership
   
   
8. Sign contract with selected solar installer
   
   
9. The solar contractor files applications for incentives and permits; the installation moves forward
   
   
10. A typical installation takes just 1-2 days, be sure to work with a tax attorney or accountant to file for tax credits once your installation is activated