For home owners struggling with today’s spiralling energy costs, any means of trying to reduce those costs now, and in the long term, is going to be an attractive proposition.
Improving domestic insulation and adopting measures to use fossil fuel derived energy more efficiently are being embraced by many as a necessity in helping to keep their diminishing energy usage still affordable.
Alternative energy sources are being encouraged by government to help meet Britain’s pledges to reduce carbon emissions, to avoid EU sanctions for not meeting pollution reduction targets and to compliment our own declining supplies of natural gas.
Desperation is beginning to cause problems for government as home owners end up with reduced disposable incomes, older power stations reach the end of their working lives and sources and supplies of imported fuels, upon which Britain is becoming increasingly dependent, become less secure and continue to fluctuate in price due global uncertainties.
Large-scale industrialisation of renewable energy production and supply is still in its infancy and can currently, and for the foreseeable future, only supplement conventional energy production due to the weather dependent nature of supply.
Not surprisingly, it is the fuel user who carries the burden of most of the additional costs.
Small-scale renewable energy collection and utilisation is a practical consideration for home owners. Many of the inhibitory factors that make renewable energy an inefficient proposition on a large scale are reduced by capturing energy on site. Energy loss through long supply networks and the cost of maintaining those networks is not an issue for domestic installations.
Although there are a number of renewable energy collecting devices and installations available for domestic use, solar water heating has become quite popular for home owners who have a suitable property.
Solar water heating works on quite a simple concept. Energy released by the sun is transferred to a liquid medium that carries the hot-water energy into the home. It can then be transferred to the domestic hot water system via a heat exchanger or added directly to the supply.
The process simply raises the temperature of the domestic hot water and reduces the additional boiler energy requirement required to bring the hot water supply up to an acceptable temperature.
Of course, the system can be made quite elaborate. Refinements can be added to improve performance but this inevitably increases installation costs.
Away from the high-pressure sales pitch that accompanies any request for information about solar water heating, the home owner can evaluate the suitability of a system by examining the practicalities.
A home owner considering installing solar water heating panels should first take a close look at how hot water usage is managed by the occupants of the property. Are baths or showers the most frequent or greatest water consumption activities?
Would the current heating system be adaptable to the integration of a solar water heating system? A modern combi boiler installation would not be adaptable. Solar water heating might have to be a stand-alone installation.
Would a separate hot water storage cylinder be required to facilitate a heat-exchanging coil or is the current cylinder suitable for modification?
Would an under-floor heating system provide a better utilisation of the heat obtained from solar energy?
Answering these and similar questions will help to establish what benefits the installation of a solar water heating system could be expected to provide.
To operate at an optimal performance, solar water heating panels need to be securely mounted on a surface that faces approximately south at an inclination of 30 degrees. A pitched roof usually provides a suitable angle. The homeowner must also consider the weight of the installation and ensure that the roof is capable of supporting it.
It is quite feasible to locate solar water heating panels at ground level if space allows. However, it is necessary to consider pumping implications if the hot water storage cylinder is above ground level.
The installation site should provide an unshaded exposure to the sky with no objects limiting that exposure as the sun moves across the sky.
The greater the surface area of the solar water heating panel, the greater the energy collection potential. A panel with a surface area of 4 m would be expected to provide up to 60% of the hot water requirement for an average family throughout the year.
Naturally, output from the panels depends upon the time of year, but during the summer months, the output can reach 100% of hot water requirement and then reduce to below 20% in winter.
There are a number of models of solar water heating panels on the market. However, regardless of elaborate claims made about efficiency, in the UK, deviating from a standard flat plate collector or a slightly superior integral collector is unlikely to offer added advantages that warrant the extra cost.
Solar water heating systems can operate by natural circulation or with the aid of a pump. The electricity demand of the pump may need to be taken into consideration where the benefits of a solar water heating system are marginal.
There is the option of installing a PV solar panel to operate a pump. These pumps do not require mains electricity, but the purchase cost of a system can outweigh the benefit.
Hot water energy generated by a solar water heating installation can be added to the domestic hot water directly, but issues surrounding bacterial and microbial production can make this option undesirable. However, a direct supply would be suitable for under-floor heating.
Energy collected and transferred via a heat exchanger, such as an enclosed coil in a water cylinder would be a suitable alternative.
Where heat is collected by solar heating panels and circulated in a closed loop utilising heat exchangers, the system can operate using antifreeze solutions to improve conductivity and allow the system to operate during sub zero conditions.
Where water is the sole circulatory fluid, the entire solar heating panel and its dedicated system will need to be drained down in winter to prevent frost damage to the components.
Apart from any draining down and pump maintenance costs, the system requires little attention other than a periodic inspection.
With the cost of a basic solar panel hot water heating installation being between £4000 and £6000, calculating the long-term energy cost savings may indicate that the benefits are marginal. However, solar heating panels may qualify for payments under the government’s Renewable Heat Incentive (RHI).
It is important to check current guidelines in respect of the continuation of RHI and to investigate any further incentives that may become available.
Solar heating panels can provide a domestic renewable energy source to compliment domestic energy requirements. Whether they reduce energy demand and cost depends on the household’s awareness of energy issues and their ability to modify their own patterns of use.