SOLAR PANELS
Thermal or Photovoltaic?
In a nutshell, there are two main types of solar energy systems today: solar thermal technology produces heat, whilst solar Photovoltaic (PV) produces electricity. Although they may look similar, they have very different functions.
Solar Photovoltaic (provides electricity)
PV panels are made from two layers of a semi-conducting material and silicon and are able to produce an electric field when exposed to sunlight.
When the sun hits the surface of the Solar PV, a small voltage of electricity is created. This electricity direct current (DC) travels to an inverter, which transforms it to AC (alternating current). It is then diverted to your fuse box and on to your home appliances around the house.
Alternatively, if not needed, it can be re-routed to the electric grid.
There are actually two types of residential Solar PV:
Stand alone off grid panels
Panels connected to the national grid via an inverter which means you can not only sell your surplus energy back to the grid, but you can rely on the grid for energy should you need to.
To be completely off-grid, you will need batteries on site to store the energy and ensure you have enough power for your home.
Solar Thermal (provides hot water)
The purpose of domestic solar thermal panels is to provide hot water for taps and showers but they can also supply hot water to radiators via a buffer tank, instead of using a boiler or heat pump to heat the rads.
These panels are comprised of tubes filled with a combination of glycol and antifreeze which are aligned next to one another and placed on the roof of a property to absorb heat from the sun.
Energy from the sun warms the fluid inside the panels and once the fluid reaches a useful temperature, it is pumped to a coil in the bottom of a solar cylinder. The solar coil heats the cylinder water for domestic use.
If the cylinder’s thermostat detects that the solar panel has not collected enough energy to heat the water to its pre-set temperature, it allows the main heat source to top it up (eg. a boiler).
The control panel can be set to optimise efficient use of the solar panel and ensure hot water is available at the times you need it.
Solar thermal systems can be combined to work with gas central heating to make sure the home has sufficient heat during the winter months.
Pro’s of Solar PV
Using solar energy helps drastically cut down the electricity you use from the national grid.
According to the Energy Saving Trust, a typical home solar PV system could save around one tonne of carbon per year, depending on where you live in the UK
Installation on rooftops is easy and does not interfere with lifestyle.
Solar energy is supplied by nature, it’s free energy
PV panels have no mechanically moving parts and require hardly any maintenance, keeping running costs to almost zero
PV panels are silent and are a perfect solution for urban areas
They have a lifespan of around 30 years with less need for replacement resulting in less waste
Solar technologies can be considered long term investments and add to the value of your property
Solar PV panels will increase the value of your property
Pro’s of Solar Thermal
Requires minimal upheaval when installing and relatively low upfront cost. A typical install costs in the region of £4,000-5,000, some of which can be recouped with the Government’s IHT scheme
Suitable for new-builds and existing properties
Produces up to 60% of a property’s annual hot water – as much as 100% in summer, reducing your energy bills
Suitable for on-roof and in-roof installation
A much smaller roof area is needed compared to Solar PV. You will need around 1sq mtr of solar thermal panel space per resident
Reduces your carbon footprint - the Energy Savings Trust says that coal-fired homes will be saving approximately 540kg carbon dioxide each year with a solar thermal install.
As there is very little that can go wrong a typical solar thermal installation can last 20-25 years
Solar thermal panels will increase the value of your property and also raise the EPC rating
Con’s of Solar PV
The intermittency and unpredictability of the sun shining makes PV panels less reliable.
For a continuous supply of electric power, especially for on-grid connections, PV panels require inverters and storage batteries, which increases the installation cost of PV panels
The efficiency levels of PV panels are relatively low (between 14%-25%) compared to the efficiency levels of other renewable energy systems.
When also considering the energy it needs for mining (for lithium, zinc, manganese and potassium for batteries), manufacturing, and discarding at the end of their life, there are many questions about how clean solar energy really is.
Con’s of Solar Thermal
Whilst solar thermal panels are efficient, they aren’t as effective during colder months. In the UK there simply isn’t the heat from the sun to make them work.
Solar thermal panels can only heat water whereas Solar PV panels generate electricity and some of this electricity can also be used to heat water. So there is more flexibility with solar PV.
Annual maintenance is recommended. This is because there are a few parts to the system like the pump and antifreeze which need to be checked to ensure that they are performing optimally.
Usually a new hot water cylinder will need to be installed so space is required to house this.
