Operations & Installation
How does a residential solar electric system work?
Solar PV modules mounted on your roof convert sunlight directly into Direct Current (DC) power. An inverter converts this DC power into Alternating Current (AC) power that can be used in your home. The system is interconnected with your utility. During the day, if your solar system produces more electricity than your home is using, the utility provider will allow "net metering" or the crediting of your utility account for returning the excess power to the grid. The utility provides power as usual at night and during the day when your electricity demand exceeds that produced by your solar system.
What are photovoltaic (PV) cells?

PV Cells were developed at Bell Laboratories in the early 1950s as a spinoff of transistor technology. When exposed to sunlight, photons of light knock electrons into a higher state of energy to create electricity. PV cells produce DC electricity, which is then converted into usable AC power by an inverter.

What is a PV module?

Commonly known as "solar panels," PV modules are made up of a collection of PV cells that make electricity when exposed to direct sunlight. These panels are called PV modules to differentiate them from solar hot-water panels or collectors, which are a completely different technology. PV modules do not make hot water, they only make electricity.

What is an inverter?
An inverter is an electronic device that converts the low-voltage DC power produced by the PV modules to conventional AC power, which can be at any required voltage and frequency.  Most electrical devices, appliances, lighting, etc. in homes and businesses run on AC electricity.
How do I know if a residential solar electric system would work on my home?
Solar electric power works for most homes. Our systems are engineered to work with most roofing materials, in most locations where direct sunlight is available. Shading from trees or other obstructions can reduce the practicality of a specific installation. A south-facing roof area is optimal, but solar electric panels can be mounted on west- or east- facing roofs and can still produce more than 90 percent of the power that a true south roof mounting would produce. It is usually more effective (and more attractive) to install the panels in the same plane as the roof direction, rather than build an awkward mount to angle them.
How long does it take to install a PV system?
It generally takes about 3 months from contract signing until system commissioning. The bulk of this time is dedicated to the acquisition of building permits and utility approvals. The installation itself typically takes less than 5 working days. Systems mounted on the ground and systems with batteries are more complex, and may take longer.
Do I need to be present when it's being installed?
Most of the solar installation can be done without the property owner on site. EmPower will generally only need access to your interior during one day to make the final connections to your electrical service panel and install your data monitoring system.
How much electricity will the system produce?

Many systems can produce all or a portion of the home's required power. The amount of power produced by a system varies depending on the size of the system, your home's orientation to the sun, the pitch of your roof and the existence of any shading on the roof. It is important to understand that a solar electric system does not need to provide 100 percent of your electricity needs to be of great value. A small system can also reduce your electric bill. We are happy to provide you with a system that supplies 100 percent of your energy needs if there is enough available roof space to do so.

How does the solar power get stored?

In a typical Grid-Connected system, power is not stored. It is either used immediately in the house or sent backwards through the meter, creating a utility credit. If storage is needed, large batteries and other equipment can be added to the system.

What happens when the utility has a power outage?

During a power outage, your system will still produce electricity, but you won't be able to use it.  Nearly all of EmPower's solar systems are directly tied to the electrical grid. The entire grid shuts down completely during a power outage to allow workers to safely fix the power lines. However, EmPower does offer a separate battery backup system that will switch on during a power outage. With a battery back-up system, part of the power produced by your solar system during the day is used to charge the batteries, which provide power for your critical loads in the event of a power outage. This ensures that you still have power when the rest of the community is busy rummaging for flashlights and candles.

Can I generate heat for home with a residential solar electric system?

No. Solar electric power systems are designed to provide electricity to power your lights, appliances and other electrical devices in your home. Other solar technologies like solar thermal are designed to turn the sun's light into heat instead of electricity.

Do I need to install a new roof before the solar panels are installed?

Most systems do not require a new roof prior to installation. However, because Solar Modules have an expected life in excess of 30 years, roofs do need to be in decent condition, as it does not make sense to remove and reinstall the panels after only a few years. After the panels are in place, they will greatly reduce the wear on the roof by blocking ultraviolet (UV) rays, snow and ice from striking the roof.

What happens if the panels get covered by snow?

Solar electric panels need sunshine to generate power. While some sun does make it through several inches of snow, little electricity is generated when the panels are covered with anything. However, because solar panels operate at a much warmer temperature than the outside air, the snow will melt off of your system and your system can continue generating electricity.  

Will my system work on cloudy days?

The amount of power your system generates is a direct result of sunlight, so it will produce slightly less energy when the weather is cloudy.

Do I need to clean the panels periodically?

Most of our customers do not clean their panels. In most areas of the country including Long Island and NYC, there is sufficient rain to clean the panels. However, if you are in an extremely dusty area (near a busy dirt road, etc.) you may see a slight performance gain from cleaning the panels monthly. If necessary, a hose stream is usually sufficient for cleaning.

What happens if the panels are shaded?

PV panels should be installed in areas where they get significant shade-free sun every day. Even small amounts of shade can significantly reduce the output. Because of the wiring design of a PV module, all of the individual PV cells must receive full sunlight for the module to work properly. If any portion of the module is shaded, the entire power output-- even those sections still exposed to sunlight-- is lowered. Our designs and installations seek to minimize the impact of any shade issues through selection of the proper equipment and proper engineering.

Will my system work at night?
No. Sunlight must be present for your solar modules to produce power. Because your panel is connected to your local utility grid, you automatically draw power from your utility at night. There will be no power interruptions - the switch between your solar system and the grid happens automatically.
Can the modules withstand high winds and hail?
The panels are supported by roofer-designed mounting systems that have been tested to withstand 125 mph winds and can work on almost every type of roofing material. Most modules can withstand one inch (2.5 cm) hailstones at 50 mph and are regularly installed in Arctic and Antarctic conditions. The face of the panels is made of tempered glass, they are quite strong. EmPower system designers always consult with a licensed Physical Engineer (PE) to properly design systems to withstand high winds (wind loading). 
How long will the system last?

PV modules last a long, long time. The oldest terrestrial modules are barely 45 years old and still going strong, so we don't know the exact length of time PV modules are capable of working. Most full-size modules carry 25-year warranties, reflecting their manufacturers' faith in the durability of these products. Cells that were put into the truly nasty environment of space in the late 1960s are still functioning well today. We measure the life expectancy of PV modules in decades, and we can confidently expect them to last in excess of 30 years. Inverters typically have a life cycle of 15-20 years with warranties up to 10 years.

What happens if my solar system breaks or stops working?
It's rare, because they are made of very inert materials and there are no moving parts to break. So, solar modules are very tough and are virtually maintenance free. EmPower offers a 10 year workmanship warranty on every system we install. On top of that, Sunpower offers a 25 year warranty on their panels and a 10 year warranty on their inverters. For the first 10 years, EmPower will provide complete service for your system at no cost to the client. Service contracts are available after this 10 year period. Enjoy your peace of mind.
Is solar electricity really cost-effective?

Yes. Your solar electric system will supply you with electricity, which will cost you less than the rates you are currently paying. Over the course of its several-decade lifetime, a solar electric system is a great investment.  It is a low-risk, high-return investment that is very competitive with other types of investments (stocks, bonds, and property). EmPower will look at your specific situation and calculate exactly what your return on investment will be and how much you will save over the life of the system. 

When will my system realize net savings?

If you finance your system, you may experience net savings as early as the first year. Instead of paying your monthly utility bill, you will make monthly loan payments for your PV system. You will effectively pay less for your loan over time than you currently pay your utility company. Residential solar power systems usually yield an initial return on investment in excess of 14%. As utility rates increase, your return will also increase. Residential systems will usually have a payback period of 4-7 years. Your exact payback period will depend on your electrical usage, electric rate schedule, and cost of your system. In most cases, larger electric bill receive a greater return on investment and a faster payback.

Will my property taxes increase?

No. Despite the fact that your property value will increase, there is New York State legislation that prevents your property taxes from increasing.

If I sell my property, what effect does PV have on the sale price?

Energy conservation and renewable generation adds value to a home. According to The Appraisal Journal: Evidence of Rational Market Evaluations for Home Efficiency, for every $1,000 in energy costs saved per year raises your home's value by $20,000. Solar energy can be one of the best home improvement investments you make.

Are there financial incentives for buying solar electricity?

Yes. The Federal government provides a 30% tax credit and New York State provides a 25% tax credit of the net installed cost after eligible utility rebates. On Long Island, PSEG offers rebates of up to $6,600; in NYC the NYS Energy Research and Development Authority (NYSERDA) offers rebates of $1.75 per watt. In addition, in the state of New York, the added value of the solar system will not increase the property tax of the building.  NYC even further reduces property taxes by 20-35%.


Other incentives for purchasing solar include:

Fight climate change

Stable electricity cost

Secure electricity supply and attain energy independence

Feeling of EmPowerment

Higher resale value for property
What is net metering?

Net metering measures the difference between the electricity you buy from your utility provider and the electricity you produce with your solar energy system. Under net metering, any excess electricity produced by the solar energy system is delivered back to the utility grid, giving you a utility credit and effectively spinning your meter backwards. Your meter spins forwards when your solar system is not producing all of the electricity you are currently using. Your electric meter keeps track of this net difference as you generate electricity and take electricity from the utility grid.

What do the terms "on-grid," "grid-connected," "grid-tied," and "off-grid" mean?

"On-grid," "grid-connected" and "grid-tied" refer to being connected to the utility electrical grid. Most solar electric systems are designed as on-grid systems, meaning that they interconnect with your existing utility service. Off-grid refers to systems not connected to the utility electrical grid. Utility rebates require that the client have a grid-connected system.

What does solar electricity do for the environment?
Your system will reduce the demand on existing fossil-fueled power plants, thereby reducing pollutants and global warming CO2 emissions. The EPA says, "using solar energy to replace the use of traditional fossil fuel energy sources can prevent the release of pollutants into the atmosphere."


TMBA is an engineering-driven firm. We were looking for a highly technical installation with a quality of support that would assure us that the system would produce value over an extended period of time. In our opinion, EmPower was the only bidder that really met that requirement. Ted Bier
President, TMBA
Commercial Client