FAQ

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What is a PV panel?
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?
By utilising 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 company.

What are the utility company requirements to connect my solar power system to the power grid?
The company that installs your system must be MCS accredited for you to recieve the FiT.

What is an off-grid solar system?
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?
Currently, the focus is based on the feed in tariff, see here for more details. There are loans and match funding floating around but they are likely to be replaced by the feed in tariff by April 2010.

What are the different types of PV panels?
There are currently four main types of solar PV panels:

1. Monocrystalline - 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. Polycrystal silicon is the “chicken nugget” of silicon, made by combining many individual crystals. They are easy to spot because they have an uneven colour, 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 polycrystalline panels.

How do I decide how large my PV solar system should be?
Typically the best return on investment is when you target the average power in watts used during the month with the lowest electric bill.

What are Standard Test Conditions (STC)?
STC is the main set of conditions used in testing solar PV modules.  Conditions are considered standard when cell temperature is 25C and you have 1000 W/m^2 of direct insolation. STC also assumes a panel is oriented to the proper angle, elevation.

How much power will a solar PV system produce?
You would calculate the total production of a system by determining the annual production of a single panel and multiplying it by the number of panels, then reduce this value to account for inefficiencies. Each system will produce a different amount of power based on the system size, orientation, insolation and so on.

What is insolation?
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.

How does shade affect the performance of a PV solar system?
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 so 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 system of 2kW will measure about 8 sq metres. 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?
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?
Facing south at the correct angle of elevation will provide the best performance (most KWh per £) however solar panels can also be installed facing towards the east or west as long as proper considerations are made. Solar panels should never face north.

What about cloudy days?
PV solar panels will generally produce electricity at a reduced rate under cloudy conditions. Severe clouds will interrupt the production of power.

How long will a solar panel system last?
Solar panels are known to last 40 years or longer. Typical guarantees of a solar panel include five 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.

How do I know if a solar PV system is a good choice for me?
If you live in an area where the sun shines and electricity is costly, chances are that PV solar panels will make financial sense for you. Contact our sales team to get assistance in evaluating your situation.

What are the maintenance requirements or other costs for a PV system?
For a grid-tied system where no batteries need to 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.

What is the warranty on a PV solar system?
Typical guarantees of a solar panel include five years workmanship and materials warranty and a 20-25 year performance warranty. The typical PV performance warranty will guarantee 90% of rated production for 10-15 years, and 80% of rated performance for 20-25 years. Please look at our products individually to see the specific warranty.

Besides the solar panels, what else is needed for a complete system?
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?
An inverter is any device that inverts DC (direct current) into AC (alternating current). In a solar installation, an inverter is a centralised 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?
In a solar application, a micro-inverter is a small de-centralised inverter that attaches directly to each panel. There are several advantages of micro-inverters; 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.

At some point it is possible that micro-inverter technology will reach a point where DIY solar installations may become possible. For now, only a licensed electrician can commission a grid-tied system regardless of the type inverter used.

Will my solar PV system include batteries?
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 spins 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?
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?
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.

What is a charge controller?
A charge controller is a device used to control the voltage and current coming from a PV solar panel array and into a battery bank.  Many of newer models employ Maximum Power Point Tracking (MPPT) which looks at the battery bank and configures the PV output to allow for the best combination of voltage and current to enter the battery bank.  While using a typical charge controller might result in a power loss of 30%, charge controller using MPPT are 95+% efficient.

How do the solar panels stand up to hail, wind etc.?
Solar panels themselves are built using tempered glass for durability and safety and are designed to withstand hail and high winds. Depending on the wind-load requirements in your area, heavier mounting hardware may be required.

Will solar panels damage my roof?
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 typical residential roof installation can be completed in 3-4 days. The number of panels and type of installation will affect the installation process.

Can I install the solar panel system myself?
It is possible for a home owner to install a solar panel system DIY (do-it-yourself). However there are many technical and safety issues to be aware of. If a homeowner is experienced with home improvement projects and is comfortable working on a roof, it is possible for a homeowner to do most or all of the work. For most DIY applications a licensed electrician should be brought in to verify the electrical part of the installation and  commission the system. In order for a system to recieve the feed-in tariff it must be signed off by an MCS accredited installer. At R-ECO, we would be reluctant to sign off work carried out by a non-member and would only do so in exceptional circumstances.

Is Planning permission required to install a PV system?
Only if you live in a conservation area or in a listed building. However, if you are unsure, we would always recommend a call to your local council.

How much will I save, how quickly will a system pay for itself?
This will vary depending on your electricity tariff, 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.

Does a solar PV system affect the resale value of my property?
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.

I rent my building – does it make sense to install a solar power system?
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.