Solar Photovoltaics Technology Information

Introduction

Solar Photovoltaic (Solar PV) panels generate electricity from sunlight. The PV cells are made from photosensitive material that generates an electrical current when exposed to sunlight. Generated electricity can be used on site or exported into the local electricity grid network (grid connected system) or stored in batteries for later use.

Back to top

Key Points

• Solar PV systems are rated by their maximum output under ideal conditions, e.g. 2kW.
• Field trials in the UK have shown that a good location can generate over 950kWh per 1kW-installed capacity per year (to put this into context the average home in the UK consumes around 4000kWh per year).
• Under a new scheme starting April 2010 called the Feed In Tariff (FIT) the government will pay up to 24p per kWh (combination of feed-in and export tariffs) for solar generated electricity. This represents an average income of £200 per kW PV installed on top of electricity bill savings. (see calculator tab for more details)
• Solar PV panels come in different sizes and materials, ranging from small PV shingles (that are a direct roof tile replacement) to large single panels 5m by 3m in size.
• The most common systems are crystalline silicon cells arranged on a panel usually around 1.5 x 1m in size with an output of around 200W. Panels can be linked into an array to provide larger power output.
• Ideally mounted systems in the UK are south facing with around a 30-degree angle to the horizontal, but other installation situations are common and perform well.
• Non ideally mounted systems can still perform well.
• Current material lifetime expectations are in excess of 20 years with less than 20% efficiency loss over lifetime.
• Nearly zero maintenance over entire lifetime of system.
• Generate electricity even on cloudy and overcast days.
• Grants available.

Back to top

Typical UK System

A typical UK solar PV system comprises of:

• A solar PV array usually roof mounted or integrated into the roof material; connected to
• The local electrical circuit via the connection system consisting of an inverter, isolator switch (safety shut off), fuse box and meters (see pic).

As you can see a solar PV system is relatively simple. However roof fixing must be carried out professionally and the D.C output from the PV units is very dangerous so wiring of a system should be carried out by a qualified electrician.

.

.

.

Back to top

Requirements

• Exposed mounting area for panels (panels vary in efficiency due to the different materials used but arrays will need about 6-15 square metres per kW installed capacity, typically around 7sqm for silicon based system).
• A grid connection point (local circuit) unless being used in a closed grid with batteries.
• A space of 1-2 square metres is needed to mount the inverter and grid connection system.
• Battery storage space if applicable.
• Solar Photovoltaic systems need exposure to sunlight, the more the better. An ideal panel location will be:
• South facing (other aspects are still good);
• 35° roof pitch (angle to the horizontal);
• Exposed to the sun for a maximum time during daylight hours with no obstructions casting shadows over any section (most solar PV systems are only as strong as their weakest link: if one panel is in shadow this causes disproportionately large losses of efficiency from the system).
• Slight variations from this ideal siting may only incur small losses in performance. With regard to angle and aspect: In the UK more than 50% of light at ground level is diffuse light i.e. light that has been reflected or refracted so it is not direct from the sun. This means that even flat roofs, vertical roofs, even east facing or west facing roofs can be suitable.

Back to top

Costs

• Anywhere from £3,000-4,000 per kW installed for a small system (1-2kW installed capacity, around 7-20 square metre area).
• Around £2,500-3,000 per kW installed for a medium system (2-5kW installed capacity, around 14-40 square metre area).
• Around £1,500-2,500 per kW installed for a large system (5kW or more installed capacity, 40 or more square metre area).
• Panels vary in cost but also with performance. The old adage 'you get what you pay for' needs to be considered when looking at cheaper brands.
• A considerable proportion of the cost is in the physical installation so ease of roof access is an important consideration.
• Grants are available: many require a certified product and installer. See FIT/grants tab above

Prices vary for solar PV systems between installers, even for the same model. Use the 'Free Quotes' button below to get quotes for Solar Photovoltaic systems specific to your location from a number of installers that operate in your area.

Use the S&G technology calculator for more on the economics of Solar PV.

Back to top

FIT/Grants

Financial support is available to many energy efficiency and microgeneration measures. Support is currently available via capital grants or the recently launched Feed In Tariff (FIT scheme) More detail about the different support available is given below.

The Feed In Tariff (FIT)

In April 2010 the UK government launched the Feed In Tariff (FIT) scheme. The FIT pays a fixed rate for any electricity generated from microgeneration systems for a set 20 to 25 year period, depending on technology type. The FIT is a technology-specific rate per kWh regardless of where the electricity is used. This means that you can generate and use the electricity and still get paid for it.

The following FIT rates apply for solar PV installations:

• Less than or equal to 4kW installed - 21.0 p/kWh
• Between 4-10kW installed - 16.8 p/kWh
• Between 10-50kW installed - 15.2 p/kWh
• Between 50-250kW installed - 12.9 p/kWh
• Between 250kW-5MW installed - 8.9 p/kWh
• Stand alone systems - 8.9 p/kWh

In order to qualify for the incentive both the system and the installer carrying out the work have to be MCS accredited. Certified installers' details are listed on the S&G installer web pages.

UK-wide Grants

LCBP Grants - As of 24 May 2010, the Low Carbon Building Programme (LCBP) is closed to all new applications. For more details click here.

Regional & Local Grants and Incentives

There are numerous regional & local grants and initiatives available as local government try to meet ambitions carbon reduction targets and other sources of funding, for example EU Rural Development Funding is targeted at sustainable development. Your local installers are best placed to access the latest information on these incentives. As part of the S & G Get a Quote function installers provide details on local incentives you may be eligible for in your area.

Alternatively you can contact your local authorities directly to try and source opportunities for support. Click here to find your local authority contact details.

Back to top

Planning Guidance

When considering any mircogeneration system it is important to find out if your building or location is:-

• in a Conservation Area or a World Heritage Site as different rules apply in these designations, meaning there are greater restrictions on the types of equipment that can be installed, particularly on the wall of a building facing a highway;
• a Listed Building identified for its historic or architectural interest; or
• Subject to an Article 4 Direction, or a condition on the original planning permission which removes permitted development rights.

In these cases special provisions apply and you should contact your local planning authority for more information (see below)

Providing your location is not covered by any of the above then solar system installations are covered under permitted development rights (no planning permission required) as long as the following conditions are met:-

For building mounted systems

• panels when installed do not protrude more then 200mm above the surface plane of the main body of the roof
• panels do not overhang building structure at any point. Maximum are allowed = 100% of roof space. Click here for Scotland specific additional requirements

For ground mounted systems

• Within the boundary of a house or flat provided panels must be set back from the highway by at least 5m and cannot exceed 2m in height anywhere within 5m of the property boundary, or 4m in height elsewhere
• you can only have one stand alone solar array (one frame for the collection of panels)
• the total surface area of the panels must not exceed 9m2 and the array must not exceed 3m in any dimension. panels when installed protrude more then 200mm above the surface plane of the main body of the roof

Due to the fact that planning in the UK is a devolved responsibility, ease of the planning process depends entirely on your Local Planning Authority (LPA). Permitted development rights for microgeneration technologies are under consultation at the moment. See 'more on planning' below for details

If you get a no obligation quote through the S & G Get a Quote function the local installers contacted will be able to advise you further. Alternatively you can check with your local planning authority (LPA) for details. The contact details of your LPA can be found by going here and entering your postcode.

Back to top

Further Information

• If you have any outstanding questions once you have looked at all the information pages relating to this technology, please write to us on info@saveandgenerate.com and we will aim to get back to you with an answer ASAP.
• We are currently developing a detailed technology guide for this technology collating all the information presented on these pages into one document. Please come back soon to download the guide in pdf format.
• For more information on solar PV panel performances please download and read our FREE S&G MicrogenVoice 1.0 - Solar PV panel performance report in PDF format
• You can also use the above email address to get in touch with our independent energy experts who will be more than happy to provide you with tailored project consultancy support if required. Click here to find out more about Save & Generate's Independent Energy Assessment services, or visit the S&G Energy Consultancy web site for more details on our consultancy services.
• Our latest independent energy expert blogs on solar photovoltaics (solar PV) provide further critical insights into developments within the industry and topics of current debate, including latest Government policy developments. Click here to read more.

Next steps to Save & Generate

• Use the above tabs to find out further information on this and other technologies.
• Use the feasibility function to instantly see how well suited your location is to these technologies
• Use the S&G Get a Quote function to receive FREE, no obligation quotes from the accredited and user rated installers working in your area.
• Make sure to review our info section on energy efficiency for options to reduce your energy consumption as far as feasible, as this will ultimately make the microgeneration equipment more economical for you.

Back to top