Is a solar PV or a wind energy system suitable for me?

SONNENSTEIN CONSULTING will advise you whether or not your site is suitable for either a solar PV or wind system. We will explain where we would propose to site the system, and the electricity output you can expect to gain from our recommended system.
If your site is unsuitable for a PV or wind system, we will advise you of this: we would never try to sell a system that is inappropriate. We do not believe it is in our interests to do this, as we need satisfied customers in order to stay in business. In order to give you additional reassurance regarding our professional conduct.

Where can I put a PV system?

When you first contact us we will ask for some information which will enable us to advise you on the best location for a PV system. The smallest PV systems (1 kWp) generally require at least 8 m2 of unshaded, southerly facing roof area.
South facing is optimum, but the system can be mounted anywhere from West facing through to East facing. The optimum angle for a system is 30 to 45 degrees from the horizontal in order to maximise output, however an angle from 5 to 60 degrees is possible, with a small reduction in output. Shading of even only a small part of a solar PV system will significantly reduce its output. This is due to the electrical connections being in series so that shading of a small part can reduce the output from the whole system.

Where can I put a wind system?

A wind turbine should be at least some distance from any obstruction such as buildings or trees. (As a rule of thumb, the distance should be 10 x the height of the obstruction). The prevailing wind direction is generally south west, so it is particularly important that the land is open to this side of the wind turbine.

Should I mount my wind turbine on a building or on the ground?

Most of the wind turbines SONNENSTEIN CONSULTING can "desing/advise/supervise" are ground mounted. Ground mounted small wind turbines are a straightforward, well proven technology which we are confident to recommend to any customer with a suitable site. Building mounting of wind turbines is far more complex, and will only be suitable in certain situations.
SONNENSTEIN CONSULTING’s staff have substantial experience of "desing/advise/supervise" wind turbines on buildings and are able to offer this service. At this point in time we are not offering small, domestic sized wind turbines for building mounting but do expect these to be available in the near future. However, for larger installations e.g. office blocks, blocks of flats, we are able to install larger 2.5 kW or 6 kW wind turbines on buildings.

What types of roof can support a solar PV system?

Solar PV systems can be mounted on almost all roof types e.g. tiled, flat roofs, metal roofs. Where the installation is to be on a flat roof we will usually supply a mounting system which ensures that the solar PV modules are mounted at an angle to maximise their energy production. We will generally require full details of the roofing system proposed so that we can design a means of attaching the solar PV system to the roof. Loading issues can sometimes occur with flat roofs or metal roofs – please contact us for details of equipment weights so that calculations can be carried out.

What performance / electricity output can I expect from a solar PV system?

A solar PV system facing due south, installed at an angle of 30 degrees from the horizontal and unshaded can be expected to produce an average of 800 kWh/kWp/annum in the UK climate. This means that a 1 kWp solar PV system will produce 800 units of electricity each year and a 2 kWp system will produce 1,600 units.
A typical, 3 bedroom house will use 3000-4000 units of electricity per year. A 2 kWp PV system will therefore produce roughly half of this. However, electricity consumption can be reduced via energy saving methods so that a 2 kWp PV system could supply a higher proportion of your electricity.

What performance / electricity output can I expect from a wind system?

The output from a wind turbine is hard to predict and is highly dependent on local climatic conditions. We will always advise with your quotation the output predicted by the manufacturer of the turbine (you can find these figures in the manufacturer’s literature which we will supply). We will never be able to guarantee an output from a wind turbine, and will not be able to give an accurate estimate if wind monitoring is not undertaken prior to installation of the turbine. However, we will advise whether your site is suitable and whether you could expect to obtain the manufacturer’s stated output. The average wind speed at your site from the NOABL database should be at least 5 m/s for a wind turbine to be installed. See the Windspeed Database to look up the wind speed for your site.

How reliable are solar PV and wind systems?

Both PV systems and wind turbines are extremely reliable. PV modules are provided with a 25 year warranty and have no moving parts so that failures are extremely rare. Wind turbines and their associated controllers come with a 2 year warranty, and the expected lifetime of most turbines is 20 years. The inverters for both wind turbines and solar PV systems are supplied with a 5 year warranty.

Will I need planning permission?

A solar PV system will generally not require planning permission, unless you are in a conservation area or National Park, or the system is to be installed on a listed building. However, it is always advisable to check with your local planning authority before proceeding.
A wind turbine will usually need planning permission. We can provide a ‘planning pack’ which will provide all the information required by the planning authority in order to progress a planning application.

Will a site visit be required?

We provide initial advice over the telephone and via email and can make an initial assessment from photographs. Site visits are expensive, so we generally only carry these out once we have provided initial advice and concluded that it is likely that an installation will be feasible and you are keen to proceed.
We are often able to provide quotations for domestic solar PV systems on the basis of information you provide and photographs without a need for a site visit.
For larger solar PV systems and for wind turbines a site visit is usually necessary.

Will a solar PV system or wind system be compatible with my current electricity system?

SONNENSTEIN CONSULTING will design, supply and "desing/advise/supervise" a complete system that can be linked into the existing electricity supply in your building, no additional work will be required to provide a fully functioning system. Generally, no modification of the existing electrical system is required, we simply need a spare way in your fusebox to connect into (and if this is not available, we will install the necessary additional equipment).
Permission is required from the local Distribution Network Operator (DNO) to connect the solar PV or wind system to the electrical network. However, SONNENSTEIN CONSULTING will take care of this application and permission to connect is automatic for small-scale systems. For larger scale systems we will advise if we think there may be an issue with connection, and liaise with the DNO early on in a project to resolve any issues that arise.

What happens when the PV / wind system is not generating electricity, or generates too much electricity?

Most systems that we install are grid connected. This means that if the PV or wind system is not generating sufficient electricity for your needs, the additional requirement is automatically drawn from the grid electricity system. If you generate more electricity than you are using, this is automatically exported to the electricity grid.
For off-grid systems, the system will be designed with batteries to store any excess electricity generated. The batteries will be sized to provide sufficient storage to ensure that there should always be electricity when needed (or a diesel back-up may be used).

What happens when there is a power cut?

When there is a power cut, your solar PV or wind system will immediately disconnect from your electricity system and cease to provide power. This is a safety requirement so that injuries do not occur to those working on the grid electricity system. Unfortunately, due to safety regulations, a solar PV or wind system cannot provide power during a power cut.

Are there any maintenance issues I should be aware of?

Solar PV modules generally have a 25 year warranty and maintenance is very unlikely to be required. Cleaning of the modules is not normally necessary as they will be cleaned by rainfall. However, if they are mounted at a shallow pitch or in a dirty location, cleaning may be required. The remainder of a PV system, including the inverter, is usually located in the loft of a house or in a plant room and therefore can be accessed in case of a fault.  Regular maintenance is not required.
Inverters carry a 5 year warranty and manufacturers state a 20 year lifetime. Therefore very occasional replacement / maintenance can be expected.
Wind turbines have moving parts and therefore do require annual maintenance in order to keep them in good working order. Some of the turbines we supply require a 3 month maintenance check in order to ensure there are no problems. SONNENSTEIN CONSULTING can carry out the "desing/advise/supervise", either on a one-off basis or as part of a maintenance contract.

Can I get a grant towards the cost of a PV or wind system?

Most public bodies and private individuals will be able to get a government grant towards the capital cost of installing a PV or wind system. Some private companies will also be able to get grants. See www.lowcarbonbuildings.org.uk for details.

How do I get payment for additional electricity that I generate and do not use?

The following website gives information on electricity suppliers that will provide payment for exported electricity:
ecocentre.org

What is the payback period for a solar PV or wind system?

Financial payback periods are long – around 10 years for wind turbines and 20 years for PV systems (when grants are taken into account), but payback periods will continue to improve if energy prices continue to rise. Most clients reasons for installing systems are environmental commitment, long-term benefit for residents of the buildings or protection against future energy price rises, rather than simply current financial considerations.
A simple payback calculation for wind can be based on a 6 kW turbine producing 12,000 kWh/year. On a typical domestic tariff, you would be paying around 10p/kWh for electricity, and you can also claim the value of ROCs* at around 5p/kWh. This means that at today's prices, the wind turbine would save you around £1800 / year. If you paid £20,000 for the turbine, the payback period would be of the order of 11 years.
A simple payback calculation for PV can be based on a 5 kWp PV system producing 4000 kWh/year. On a typical domestic tariff, you would be paying around 10p/kWh for electricity, and you can also claim the value of ROCs* at around 5p/kWh. This means that at today's prices, the PV system would save you around £600 / year. Assuming that the PV system cost £25,000 and you received a 50% grant reducing the cost to you to £12,500, the payback period would be of the order of 20 years.
*ROCs = Renewable Obligation Certificates

Will a solar PV system provide hot water?

Solar PV systems generate electricity, not hot water. Electricity can be used to heat water e.g. via an immersion heater. However, if you want a system that heats water directly you need a solar water heating system, not a solar PV system.