Heat Pump or Solar Panels?
When it comes to cutting domestic energy costs by adopting modern technology solutions such as heat pumps or solar panels, there is no definitive answer to the question of which delivers the most benefit. Both technologies offer benefits but with an array of caveats some of which increase the benefits of one over the other and some which limit them. Installation costs for both are substantial so while both can cut your energy usage, payback times are lengthy and the financial benefits of neither will be short term but given the right circumstances, can be well worth while, particularly if Government grants or financial assistance with installation costs can be accessed. It also has to be recognised that under certain circumstances, it can be beneficial to combine the two technologies for added energy cost savings.
To explain the technologies in simple terms, solar panels absorb heat from the sun. There are two types of solar panel; solar photovoltaic (PV) panels, which generate electricity from sunlight, and solar thermal panels, which generate heat for use in your domestic hot water cylinder. There are also two main types of heat pumps, air source, which take heat from the air and ground source which extract heat from underground.
Solar, would correctly indicate the involvement of the sun in generating energy and therefore to get the maximum benefit from solar panels they are best used in climates where there is more sunlight. Solar photovoltaic (PV) don’t need direct sunlight to work and will even work on cloudy days, although the stronger the sunshine, the more electricity they will generate. Solar thermal panels likewise do not require direct sunlight, although it is also important to install them where they will be exposed to as much direct sunlight as possible, such as a south facing roof or corner of the garden as they do not necessarily need to be sited on a roof.
Solar panels generate direct current (DC) electricity, but domestic electricity is alternating current (AC), therefore an inverter needs to be installed along with the system to convert DC electricity to AC. This electricity can be used throughout your home, or exported to the grid, which would generate an income to the household. It is also possible to install batteries which can absorb electricity from your solar panels allowing you to use electricity generated during the day in the evening or during the hours of darkness.
One of the much discussed aspects of owning an electric vehicle is the rising cost of the electricity required to recharge the vehicle’s batteries, but by installing solar panels and the additional batteries to store, what is in reality, free electricity, you can in essence, charge your vehicle at little or no cost.
As well as lowering your energy costs, solar panels have the added benefit of reducing your carbon footprint. The cost of installing a solar panel system will vary with the number of panels you use, whether you use tiles incorporated into the roof, panels mounted on the roof or if opt for a ground sited installation.
A heat pump, either air source or ground source transfers heat from the outside which is absorbed into a fluid. This is then passed through a heat exchanger into the heat pump, which raises the temperature and then transfers that heat to water, which is used to heat your home via central heating radiators or underfloor heating as well as heating water stored in a hot water tank for general domestic use. Renewable heating systems do not heat water to as high a temperature as gas or oil boilers. This means they’re better suited to homes with large radiators or, even better, underfloor heating, as the larger surface area allows heat at the slightly lower temperature to spread around the room more efficiently.
There are two types of air source heat pumps, one piece, monobloc systems and split systems. The monobloc system is contained in a single unit sited outdoors. It has pipes carrying water to a hot water tank inside the property and to the central heating system. A split system has only part of the system sited outside the property with the other part inside.
Monobloc systems tend to be less expensive than split systems, quicker and easier to install and take up less room in your home, They are generally, however slightly less efficient than split systems. The efficiency gain from split systems comes from some of the heat transfer taking place inside your property where the air is warmer, resulting in less heat being lost. Both systems make use of a large fan which draws the air into the system, so therefore they do make a little noise; similar to a domestic fridge, the colder the air temperature, the harder the fan has to work and the noisier it becomes. If the system is thoughtfully sited, the noise from the fan will never become a distraction and is unlikely to be heard inside the property.
It is also worth noting that a normal air source or ground source heat pump installation cannot produce hot water on demand in the way that a combi boiler does. That being the case, you would need to make provision for a hot water storage tank big enough to cater for your household’s usage of hot water
Ground source heat pumps, as the name would suggest, draw heat from the ground rather than from the air and as such they need pipes buried underground. These underground pipes can be fitted horizontally or vertically, depending on the space available in your garden. Vertical boreholes are drilled down to between 15 and 100 metres, whereas horizontally fitted pipes would be buried in a trench of around 2 metres deep. This would be very disruptive to your garden, as the area taken up by the buried pipe should be around three times that of the floor area of your house, including the upper floors.
Ground source heat pumps use electricity to pump water around the pipes but they generate heat from a renewable source. Despite the fact that they use electricity, a well installed ground source system will generate around 3-4Kw of energy for every Kw of electricity used, which amounts to an efficiency of around 300%.
It is also possible to store and use electricity generated from solar photovoltaic (PV) panels, to power a heat pump and as this is electricity from a renewable, free source of energy, by using it to power your heat pump air source or ground source heat pump, you can increase the cost effectiveness of this method of water heating for the whole house.
The installation costs of solar panels will vary depending on the number of panels you install and where you site them. The cost of installing a heat pump depends on the type of system you opt for, with typical costs for an air source system of around £7,000 to £13,000, while a ground source system could total £10,000 to £18,000.
To help with the cost of installing heat pumps, the government is providing grants to property owners to install them through the Boiler Upgrade Scheme (BUS). This scheme is open to domestic and small non-domestic properties in England and Wales and will run from 2022 to 2025. The scheme will provide grants of £5,000 against the cost and installation of an air source heat pump and £6,000 off the cost and installation of a ground source heat pump.
Before embarking on a renewable energy installation such as solar panels or heat pumps, get advice from experts in that field, check their credentials such as trade body membership or accreditation and look at their track record of past projects in your area and always get more than one estimate for any work you are planning.