FREQUENTLY ASK
QUESTIONS
HOW MUCH POWER DO WE USE IN THE HOME ?
Everyone consumes energy, but sometimes it is hard to know just how much power
is really being used in the home. Domestic electrical usage is measured in
kilowatt hours (kWh) and the best way to understand what this means is to look
at what a kWh does in everyday life.
A
kWh of electricity can provide:
o
1200 electric shaves
o
Drying your hair 15 times
o
Listening to 15 CD’s
o
Using a small refrigerator for 24 hours
o
Microwaving 20 meals
o
4
evenings of light with 60W incandescent lamps
An average 3 bedroom house uses between 9-10 kWh per day (Source: Energy Savings
Trust)
WHAT IS SOLAR PV?
Solar PV
is a renewable energy system which uses photovoltaic modules on the roof of a
building to convert light into electricity. Voltaic cells are made up of thin
layers of semi-conducting material (usually crystalline silicon) which generate
an electrical charge when exposed to direct light.
HOW DOES SOLAR PV
WORK?
A Solar PV module is
made up of mono-crystalline cells which consist of two or more thin layers of
semi-conducting chemically treated silicon materials. The chemicals react when
light hits the cell, creating an electric field across the layers, producing a
direct current. The greater the light intensity, the greater the flow of
electricity. This direct current (DC) is then fed into an inverter which changes
it into a usable alternating current (AC).
WHERE DID THE IDEA OF PV COME FROM?
In 1839, a French scientist named Edmund Bacqueral discovered the photovoltaic
principle and the first basic solar cell was developed some 40 years later.
However, today’s photovoltaic technologies were developed in the 1950’s and
1960’s for uses including satellites, spacecrafts, electronic watches and
calculators. The idea behind the domestic use of PV to provide renewable power
for the home, has now been established for over 20 years.
WHAT
ARE THE KEY BENEFITS OF D I S CONTRACTORS SOLAR PV?
The D I S Contractors Solar PV system has many unique features. It is available
in simple kit form ranging from 0.54kW (3 modules) to 2.88kW (16 modules),
making ordering straight forward. Bespoke systems of almost any size can also be
designed and supplied using the same basic components found in the kits.
The systems utilize 180 Watt monocrystalline D I S Contractors Solar PV modules.
The module frames are made from corrosion proof, anodized aluminium and meet the
highest requirements in terms of stability and durability.
WHERE CAN I INSTALL
MY PV MODULES?
The location of the PV
is vitally important. The modules must receive the maximum amount of day light
possible, so it is not advised to install the modules in situation where
surrounding buildings or trees may cast shadows. The best location for a PV
solar module is on a south-facing roof. Various mounting arrangements including
on-roof, in-roof and flat roof kits, both landscape and portrait.
WHAT'S THE DIFFERENCE
BETWEEN SOLAR THERMAL AND PV?
As previously mentioned,
Solar Panel PV systems use energy from the sun to generate electricity with roof
mounted modules. Solar Thermal employs roof mounted collectors to absorb energy
from the sun. These collectors are usually connected to the lower coil of a
twin-coil cylinder via a sealed circuit containing a special glycol/water
solution. The pump in the system circulates the heated fluid from the collector
to the cylinder, where the stored water is heated for use in the home.
WHAT HAPPENS WHEN THE
WEATHER IS CLOUDY OR COLD?
Solar PV Panels use
light to generate electricity, so the modules still work when it is cloudy,
although when it is overcast they are less efficient. When it is slightly
overcast, the panels may produce as much as half the power they would in sunny
conditions. When the sky is heavily overcast, this could reduce further.
Temperature is less important than how much light there is. What’s more, a clear
cold day is perfect, because PV modules operate better at cooler temperatures.
WHAT HAPPENS IF THE
MODULES GET DIRTY?
Solar PV modules are
self cleaning when mounted at an angle of at least 15º. The amount of dirt on
the modules depends on their location. If the modules are in a heavily silted
area (e.g. under trees) the build up of dirt may reduce the power the panel
generates by around 10%.
WHAT IS THE EXPECTED
LIFESPAN OF SOLAR PV?
Solar PV modules should
be expected to last at least 25 years, since there are no moving parts. The
modules have a twenty-five year performance guarantee.
CAN I SELL THE
ELECTRICITY I PRODUCE BACK TO THE ENERGY SUPPLIER?
Most electricity
suppliers will pay for power fed into the Grid (feed-in) from domestic Solar PV
systems. The easiest way to do this is by signing up to a ‘Buy Back’ or ‘Feed-in
Tariff’ scheme with your power supplier. There are two main types of tariff
available:
Generation: You are paid
for all of the electricity that your solar PV system generates even if you
consume it in your home.
Export: You are paid for
just the electricity that is exported back to the Grid and not for any
electricity you have consumed.
WHAT ARE FEED-IN
TARIFFS (FiT)?
On 1st February 2010,
the Government announced new standard generation Feed-in Tariffs (FiT) rates due
to start on 1st April 2010, which are guaranteed for 25 years. This new payback
scheme, results in a shorter payback for Solar PV systems, making them an
extremely attractive green option for any home. PV systems registering with the
scheme between 1st April 2010 and 31st March 2011 will benefit from the
following:
Any system less than 4kW
on a new build = 36.1p per kW pay-back
Any system less than 4kW
on a retrofit = 41.3p per kW pay-back
Any system 4-10kW new
build or retrofit = 36.1p per kW pay-back
Any system 10-100kW new
build or retrofit = 31.4p per kW pay-back
This means that if you
normally pay 12p per kWh for your electricity, you would effectively get both
the power consumed for free and the FiT. So on a retrofit system below 4kW this
would mean 12p + 41.3p = 53.3p per kWh saving!
Any Solar PV system
installed after the 15th July 2009 is eligible for this Feed-in Tariff at the
above rate, provided the system uses MCS approved equipment and has been fitted
by an MCS accredited installer.
WHAT IS THE DIFFERENCE BETWEEN POLYCRYSTALLINE AND MONOCRYSTALLINE MODULES?
The polycrystalline modules use cells made from a multicrystalline silicon
material with a blue marbled appearance. The monocrystalline modules have cells
of a darker appearance, almost black in colour. These are produced from a pure
single crystal silicon, resulting in a cell which is slightly higher in
efficiency than the multicrystalline silicon cell. Thus the monocrystalline
modules are typically smaller in physical size than a polycrystalline one of the
same output.
WHAT MOUNTING OPTIONS ARE AVAILABLE FOR D I S CONTRACTORS SOLAR PV?
There are several different mounting arrangements available including on-roof
and flat-roof (by special order), with both landscape and portrait module
installations possible.
HOW ‘GREEN’ IS D I S CONTRACTORS SOLAR PV?
D I S Contractors solar PV is a renewable energy source that does not require
the burning of fossil fuels to generate electricity and does not leave a carbon
footprint as it creates no carbon dioxide during operation. For each kWh of
electrical energy generated using a fossil fuel, about 1.5lb (0.68kg) of CO2 is
released into the atmosphere and the average person uses around 600-800 kWh of
energy every month.
D I S Contractors Solar PV makes no noise, emits no pollutants, creates no waste
and uses no fuel, meaning it is a VERY green energy supply.
HOW LONG IS A SOLAR PV SYSTEM GUARANTEED FOR ?
All D I S Contractors Solar OV systems are covered by a unique five year
manufacturer’s guarantee, subject to the system and its components e.g inverter,
modules, etc being supplied by D I S Contractors as a kit. Please note that D I
S Contractors do not warranty mixed systems i.e. those which include an inverter
or modules that have not been supplied by D I S Contractors. For further
information, please contact the D I S Contractors Customer Service Department.
Tel 01522 825825
D I S Contractors Solar PV modules also carry up to a 25 year performance
guarantee as follows:
Performance guarantee to 90% output minimum after 12 years
Performance guarantee to 80% output minimum after 25 years.
