Common Solar Power Questions

Below are answers to many common questions about solar power:


Is solar a safe investment?

A: The minute you turn on your system, your solar array becomes a revenue-generating asset. Locally produced, directly distributed energy systems like solar helps you garner independence from imported fossil fuels and will protect you from energy rate hikes.


Does a solar PV system affect the resale value of my property?
A: Yes it does. Available real estate property resale value data indicates that money spent on solar panel installations is recoverable and may actually increase the value of the home beyond the amount spent.


Will the system work on gray, cloudy or overcast days?

A: Yes, because photovoltaic energy (PV or solar power) uses the full spectrum of light, the ultraviolet rays are still charging the system, even when the sunlight isn’t visible.


How does my solar array work with the utility grid?

A: The solar panels generate electricity when exposed to sunlight. This electricity is conditioned by the power inverter to match the electricity coming from the utility grid.


Does the system work when the regular power (the utility grid) is down?

A: Yes, if you choose a system that has a battery pack, it will provide power to those circuits you select as critical loads. You might choose the refrigerator, computers, some lighting circuits, heater fan, TV or whatever you feel should have back-up power.


Does a warranty program cover the system? How long will my solar PV system last?

A: We provide a 10-year complete system warranty, including labor and equipment. Solar system components carry 25 year warranties. With proper maintenance your system should last for a minimum of 25 years.


What happens when we generate more power than we’re using?

A: Net Metering is one of the many benefits of renewable energy, which allows your electricity meter to spin forwards when electricity flows into your house and backwards if your system produces more energy than is immediately used. You are billed for the difference between the electricity you generate and the energy you use. To find out more about solar energy and incentives, go to the Solar Electric Power Association (SEPA) website.


What is Net-Metering?
A: Net Metering is a useful tool in the field of alternative energy. For owners of PV systems, net metering provides an opportunity to sell excess electricity produced to your local utility company. In North America, forty states currently have net metering policies in place. Net metering means that the amount of solar electricity produced (measured in KWh) is subtracted from your overall usage, meaning you only pay the utility for the difference (the “net” amount).


What is a PV panel?

A: A PV solar panel, referred to in the industry as a solar module, is constructed by connecting photovoltaic cells (or PV cells) to produce electricity. The cells are a semiconductor-based technology that converts solar radiation into direct current (DC) electricity. Solar panels for grid-connected home or business use typically use 60 or 72 PV cells.


What are the benefits of using PV solar systems? A: By utilizing PV solar cells, home or business owners are able to generate electricity from sunlight saving money and avoiding the harmful pollution generated by traditional methods of generating electricity. This solar generated energy is used to offset or replace power that would normally be purchased from the utility.


What are the utility company requirements to connect my solar power system to the power grid?

A: The requirements vary depending on the size of the system and the particular state and/or utility. In some states a special meter must be obtained from the power company. Information can be found here:


What is a grid-tied solar system?

A: 98% of PV solar panels installed in the USA are grid-tied systems, meaning that the system is tied to the power grid (local electric power utility company). The solar power is added to the grid power, reducing the amount of power that must be purchased from the utility.


What is an off-grid solar system?

A: An off-grid solar energy system is where there is no connection to the utility company power grid. This type of installation requires a charge-controller, a bank of batteries and in most cases an inverter, so that electric power requirements can be met at night or during cloudy conditions.


What incentives are offered for users of PV solar systems?

A: Currently, the Federal gives a personal or business tax credit of 30% of the cost of a PV system. Many states also offer additional incentives for utilizing PV solar products. Click here for more information.


What are the different types of PV panels?

A: There are currently four main types of solar PV panels:


    1. Monocyrstalline - these are made from cells created by cutting thin slices from single crystal silicon block and are higher in efficiency, but also higher in cost per watt. They are easy to spot      because they have a smooth even color, usually black.
    2. Polycrystalline – these are made from cells created by cutting thin slices from polycrystal silicon block and are slightly lower in efficiency, but also lower in cost per watt. Polycyrstal silicon is the“chicken nugget” of silicon, made by combining many individual crystals.  They are easy to spot because they have an uneven color, usually blue.
    3. Multicrystalline – a different term for polycrystalline.
    4. Thin film – these are made by depositing a thin layer of very finely powdered silicon (amorphous silicon) or other photovoltaic material, on a substrate. These are much lower in efficiency that crystalline cells, and somewhat cheaper per watt. They are a good choice for large ground mounted utility scale solar arrays where real estate is plentiful. Their low efficiency makes them undesirable for commercial and residential applications because they consume a large amount of roof space compared to mono or poly panels.


What is insolation?
A: Insolation refers to a daily total of direct sunlight. In the solar industry it usually refers to the average daily hours of sunlight equaling 1000 watts per square meter. On average, locations within the USA will get between 4 and 6 hours of insolation per day depending on season and location. Click here to see a zip-code based solar insolation calculator.

How does shade affect the performance of a PV solar system?
A: One of the leading causes of power loss in a solar PV system is when part of the panel or array becomes shaded. In a panel there will usually be either 60 or 72 cells connected together. Each cell produces a certain voltage and amperage, the cells are configured and connected in a combination of series and parallel connections to produce the correct amount of power. If any individual cells performance is degraded by shade, the performance of the entire panel will fall to a point relative to the worst performing cell. Likewise, in a string of panels, the entire string suffers performance reduction to that of the lowest performing panel. A solar installation should be designed in a way such that none of the panels are even partly shaded at any point of the day.

How much roof space does a PV system need?
A typical solar panel of 200Wp will measure about 17 square feet. Depending on installation factors, the required square footage of roof space will be somewhat larger than simply the area of the panels. Based on your information, once our engineering department has determined the required angle, shading factors, etc. we can give you a more accurate number.

Do solar panels have to be installed on the roof?
A: Solar panels can be installed on the roof, on the side of a building, on the ground or on a pole. The most cost effective installation will usually be on a roof, but if roof or shading conditions prevent the use of the roof we can help you review other options.

Do installed solar panels have to face a southerly direction?
A: In the USA, facing south at the correct angle of elevation will provide the best performance (most KWh per dollar) however solar panels can also be installed facing towards the east or west as long as proper considerations are made. Solar panels should not ever face north.

How long will a solar panel system last?
A: Solar panels are known to last 40 years or longer. Typical guarantees of a solar panel include ten years workmanship and materials warranty and a 20-25 year performance warranty. The typical PV panel performance warranty will guarantee 90% of rated production for 10-15 years, and 80% for 20-25 years. Solar panels are designed to withstand hail, severe wind and weather conditions assuming proper installation.

What are the maintenance requirements or other costs for a PV system?
A: For a grid-tied system where no batteries need be replaced, there is typically little or no maintenance required. You might consider a periodic inspection to ensure that the panels remain clear of leaves, dirt, bird droppings etc. Other than that, unless there is an equipment failure there should be no maintenance required.

Besides the solar panels, what else is needed for a complete system?
A: In a grid-tied system, local power company regulations must be met, each are is different. Otherwise, the system will include the panels, mounting hardware, connecting wires, and an inverter to convert the DC power from the panels into the correct AC voltage.

What are solar inverters?
A: An inverter is any device that inverts DC (direct current) into AC (alternating current). In a solar installation, an inverter is a centralized device that connects to and manages the performance of the solar panel array; it aggregates the DC power coming from the panels or strings of panels and inverts the DC power into single phase (or three phase) AC power at the correct voltage for delivery into the users electrical system, and provides equipment protection and safety features. The better inverters on the market also allow for data logging and web-based remote monitoring of important performance metrics and power generation.

What are micro-inverters?
A: In a solar application, a micro-inverter is a small de-centralized inverter that attaches directly to each panel. The advantages of micro-inverters are several; they may be safer for the installer because they eliminate high voltage DC in the system and instead use household type power; installation may be quicker, and, performance of the panels or strings can be improved if there are shading conditions or otherwise poorly performing panels within the array.

Will my solar PV system include batteries?
A: When you connect a solar PV system to the grid, you are essentially using the grid as a battery. When solar power exceeds your usage, the utility meter spins backwards. When demand exceeds solar production, the meter sins forward. The utility company grid acts just like a battery. In a grid-tied system you do not need batteries.

Will the solar electric system function as “back up” power when the utility power is not available?
A: Not in a normal grid-tied PV solar installation. In a grid-tied system, the inverter will shut off if the power company grid is not also providing or able to provide power. This is more of a safety feature than a technical limitation. To have a back-up battery system, you would need to take the same steps as if there were no solar involved, i.e., install some type of UPS system. Another approach would be to install a hybrid on/off-grid system through the use of a special charger-inverter and batteries.

Can I power my entire building with solarpanels and disconnect from the utility company?
A: Yes you can. In an off-grid installation, you must have batteries, a MPPT charge controller and an inverter – in some cases the batteries will cost nearly as much as the solar panels and only last 6-8 years before replacement becomes necessary. Off-grid solar is achievable, but is very costly and only recommended for locations where there is no grid to connect to.

Will solar panels damage my roof?
A: Properly installed solar panels will not damage your roof. If your roof is near the end of its expected life, it might be a good idea to consider replacing the roof before adding solar panels, because removing and reinstalling the panels can add to the cost of a roof replacement.

How long does it take to install a PV system?
A: A typical residential roof installation can be completed in 3-4 days. The number of panels and type of installation will affect the installation process.

Is a building permit required to install a PV system?
A: A professional installation will nearly always require a permit. A call to your local city government (electrical inspector) would clear this up.

How much will I save, how quickly will a system pay for itself?
A: This will vary depending on the local cost of electricity, state and local rebates or incentives, and the installed cost of the solar panel system. The range can be from 3-4 years up to 20 years depending on these factors.

How do I qualify for and take advantage of state and federal subsidies, rebates or incentives for solar power?
A: Each individual situation is different and it is suggested that you consult with a tax professional. Alliance Energy Group will provide trained staff to assist you in evaluating the available incentives. Energy Star has a resource for federal tax incentives here
More information is available here

I lease my building – does it make sense to install a solar power system?
A: It may, depending on the length of your lease and other factors. For tenants interested in a solar installation, some discussion and agreement with the building owner will be required. In general it is also beneficial to the owner, particularly if it does not require any payment on his part.