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422A Upper Richmond Road West, Sheen, SW14 7JX

F.A.Q – Solar Thermal

Q: Can solar water heating provide central heating?

A: No. Unfortunately in the UK it does not make any sense to use a solar water heating system to drive the central heating. In the summer when the sun is warm enough to provide sufficient energy there is no need for central heating, and in the winter when the central heating is switched on, there is nowhere near enough energy from the sun to provide the volume of hot water required by a central heating system. In some European countries it is common practice to install a very large array of solar panels and generate sufficient energy to supply a central heating system. This is because, in countries such as Austria and Germany, although the ambient winter temperatures are cold, the sunlight is still strong enough to provide sufficient energy. However, in the UK the sunlight is much weaker in the winter, partly because of cloud cover and partly because we are further north.


Q: Can I use my existing boiler with a solar water heating system?

A: Yes, normally they will work together very well. In the winter, when the sun does not provide sufficient energy to ensure a supply of hot water, it is no problem for the boiler to take on this demand because it is already running and providing central heating. And in the summer months when the boiler is normally switched off because the central heating is not in use, very often the sun will provide sufficient hot water for your shower, bath, washing machine and dish washing needs.


Q: I have a combi boiler: can I still use solar water heating?

A: Yes, provided you have sufficient space for a hot water cylinder. The combi boiler itself is normally not a problem, but all solar water heating systems must have a hot water storage tank at least as large as a conventional hot water cylinder.


Q: Do solar panels generate electricity?

A: There are two types of ‘solar panels’ and they are based on completely different technologies. Solar Water Heating systems, also known as Solar Thermal systems, supply only hot water. Solar Photovoltaic or Solar PV systems generate only electricity.


We supply the former: solar hot water systems are very cost-effective, efficient, practical and inexpensive compared to solar PV systems – a solar water heating system can pay for itself in financial terms in as little as ten years. They integrate perfectly with our automatic wood pellet heating systems and with many existing heating systems. A solar water heating system is probably the single most practical and worthwhile renewable energy technology for most people in the UK.


Solar PV systems are expensive and complex. As well as the panels themselves, they normally require an inverter system and either a bank of batteries or a connection to the electric grid. A solar PV system will typically cost tens of thousands of pounds and will not repay its installation cost for 30 years or more.


Q: My roof is in the shade or north facing. Can I still use solar water heating?

A: Realistically, no. In order to be both energy- and cost-effective a solar panel must have full sunlight whenever it is available. However, a number of alternatives are available for people who do not have a south-facing roof in direct sunlight. Solar panels can be mounted on an inclined frame attached to an east or west facing roof in order to ensure that the panels themselves face south-east or south-west. If no suitable roof is available at all, panels can be installed on a free standing frame which can be situated adjacent to the building, or even a small distance away from it in order to capture maximum sunlight.


Will solar thermal panels work in winter?

Yes, however they will unlikely be able to
satisfy all of your heating needs at this time
of year alone. In winter, your heating demand
will be higher but there is less solar energy
for the panels to absorb, and so it should
likely be combined with another technology
to satisfy all of your heating needs.


How many solar thermal panels do I need?

Typically you need between 0.6 to 1 m2 of collector (solar panels) per person living in the house. We would suggest two solar thermal flat plate collector panels for a four person household.


Will my roof be strong enough?

Most roofs are strong enough to support a solar thermal panel system. Our approach is to carry out a structural assessment of every roof to be sure that this is definitely the case. Occasionally, we may specify a need for some reinforcement work to be carried out.


How do the panels connect to my existing hot water cylinder or tank?

Your hot water cylinder will be replaced with a high efficiency twin coil cylinder. The solar panel will heat the bottom of the tank and your boiler will top up the heat if required. It is sometimes possible to retain your existing cylinder and retrofit a second heating coil, although this can impact on efficiency. The solution best for you can be assessed by our expert team.


How much disruption will there be inside the house during installation?

It depends on the current hot water plumbing within your home and its relative proximity to where the solar collector will be installed on your roof. In most cases much of the work will take place inside your loft space. We will advise on the potential disruption once we have surveyed your property and will plan your project to minimise disruption as much as possible.


Is There Enough Sunshine In The UK To Make Solar Energy Viable?

Yes, although they work best in direct sunlight, good performance can still be achieved on a cloudy day (diffused radiation) to operate an efficient solar water heating system, even in the North of Scotland.


How Much Conventional Energy Will I Save?

55% to 70% of the energy required to heat your hot water.


What Size Of System Do I Need?

When using an efficient solar collector you need approximately 1 square metre per 60 litres of hot water cylinder capacity.


Where Should The Solar Cylinder Be Positioned?

In the case of a single cylinder/twin coil cylinder, as close to the solar collector as possible. For preheat, as close to the existing cylinder as possible.


Will It Work During The Winter Months?

Yes, the system will work in much colder temperatures than we experience in this country. Even during cloudy days in winter you can expect some gain.


What Happens If It Snows?

If the panels are covered in snow they will not work, however there is no need to do anything.


What Should I Do If I Go On Holiday?

Just leave the system on.


Solar Thermal Hot Water - Solar Thermal Systems

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