Frequently Asked Questions
What Is Solar Power And How Does It work?
Solar panels collect the light that hits the earth from the sun. They convert the light into power that is either stored in batteries or used straight away; for example in a toy car or desktop gadget.
Solar can be used for a number of different applications, but the two main categories are:
- Producing Electricity – Photovoltaic Solar Panels (PV)
- Producing Hot Water – Solar Panel Collectors
PV Solar Panels
PV solar panels produce environmentally clean, safe electricity in the form of Direct Current (DC) electricity similar to that released by batteries. In fact most solar powered equipment uses a battery, and the solar panels are simply there as a battery charger, exploding the myth that solar powered torches do not work in the dark. This means that solar panels can be used to power battery chargers, lights, mobile phones, radios, torches, anything and everything that requires electricity. PV solar panels have no moving parts, and are therefore, silent and reliable.
PV home systems are also available, but are not common place due to their high cost and long payback period.
Solar Collectors
Solar collectors however are used for home hot water systems, as they are cost effective when savings and pay back periods are taken into account. Solar collectors come in two main forms – Evacuated Tubes or Flat Panel Collectors.
Which Is Better: Evacuated Tubes Or Flat Panel Collectors?
Each installation needs to be looked at individually, however usually the flat plates have more merit. It's all about the 'aperture area or absorber surface' which is the part of the collector that collects light and turns it into heat. It is common myth that flat panel collectors do not work on cloudy days, however all solar panels will work as long as there is light.
If you compare flat plates and evacuated tubes by metres squared of aperture area, vacuum tubes are more efficient than flat plates, but if you look at costs per solar panel, collector or system, you typically have a much larger absorber surface area on a flat plate system, so for a similar cost you would normally expect more output from the flat plates.
Orientation of flat plate collectors isn't a problem and vacuum tubes have no benefit over flat plates except on an east facing or west facing elevation where vacuum tubes would be more desirable.
As a general rule you would expect a 3m2 vacuum tube system to have a similar output to 5m2 flat plate system.
How Do Photovoltaic Solar Panels Work?
The photovoltaic effect discovered in 1839 by 19 year old Edmund Becquerel, is the phenomenon that certain materials produce electric current when they are exposed to light.
The sun produces a range of energy which we can only see a small part of as visible white light. Solar panels turn another part, or wavelength, of the light into electricity that can be harnessed. A photovoltaic cell (PV cell) produces electricity on the principle that electricity will be produced when two semiconductors are exposed to a particular wavelength of light. Groups of PV cells are linked together to form panels, the bigger the panel and the more cells, the greater the amount of electricity can be produced.
How Do Photovoltaic Solar Panels Work In The Home?
PV solar panels are connected in parallel with your existing electricity supply. Your electricity is primarily supplied by solar power, but should your solar panels not be able to provide power, for example at night, then your normal electricity supply will be used. If an over supply is being generated then this will get sold back to the grid.
Can Solar Panels Be Used In The UK?
Yes – solar works from light, so as long as there is light a solar panel will be generating energy – it will of course produce more energy on a clear day when light is not being broken by clouds.
Systems will vary in the UK from those used closer to the equator and prices will vary also. The main difference is the amount of surface area required every system will have a different efficiency rating and this too will effect how many panels you will need.
Will They Work When The Sun Isn't Shining?
Solar panels can produce electricity whether it's cloudy or sunny, just not at night. However, the more sunlight there is, the more electricity a solar panel can produce. The length of day will also effect how much electricity a solar panel can produce, meaning that summer months with longer days are a better time for charging your all important MP3 player.
How Do Solar Lights Work?
Solar lights use the power from the batteries that the solar panel has collected during the day. They typically use LED bulbs to provide light as these are the most efficient way of converting the power back into light.
At dusk the lights sense the reduction in sunlight and turn the LED bulbs on. Modern lights often have an on/off switch allowing you to override this setting if you don't want the lights to turn on.
Why Do Solar Products Have Batteries?
Solar products more often then not have batteries to store the power collected during the day for use later when required. Solar Lights are probably the best example of this, other notable product types include solar phone chargers.
These have an internal battery that you can have on standby to get your phone back up and running if you're caught short without a wall charger nearby.
How Do You Get The Best Out Of Your Solar Products?
With the right product and a little planning, solar can and does work year round in the UK. Naturally what you can expect in terms of performance in the winter is not going to be what you might get at the height of summer, but it can still do a solid job for you.
A poorly positioned panel is often the crucial difference between satisfaction and disappointment when it comes to the performance of your product.
Put simply, the fewer obstructions between the sun and your solar panel the better your unit will perform.
Your solar panel should be:
- South facing or as near as possible.
- Outside of any glass windows and wiped clean from time to time.
- Free from shadows; particularly between 10am and 2pm.
- Correctly angled towards the sun for the time of year.
Why Do Some Solar Products Work Better Then Others?
Think about rain falling in two buckets placed side by side. A bigger bucket will collect more water than a smaller bucket during the same length of time in the rain.
With solar power the solar panel and batteries represent the bucket. The panel collects the light, converts it into power and stores it in the batteries. Typically the bigger the solar panel the more light is collected.
Matching higher capacity batteries with a more powerful solar panel has two main benefits:
- More power is collected during the day.
- Any excess power can be stored in the batteries for use the next day - this means the batteries may not start each day from flat giving your product a head start on a cloudy day in terms of performance in the evening.
Other factors can have an effect such as:
- The efficiency of the panel.
- The type of solar panel.
- The capacity of the batteries.
- The type of batteries used.
How Much Do Hot Water Heating Systems Cost?
Prices do vary based on a number of factors but most professional installation companies will come to your home and give you a free no obligation survey.
Flat panel collectors can be purchased from DIY stores from as little as £1500 per panel, however what they neglect to mention is that you will require a twin coil cylinder and it is very unlikely that you will have one already!
A high quality stainless steel twin coil cylinder will cost around £700. You will also require a pump, a temperature management control unit and all the copper piping and fittings to plumb the system in. And don't forget the labour costs, it really is not a job we would recommend you do yourself.
All prices are approximate based on an average installation:
- Panel x 2 = £3000
- Cylinder = £700
- Pump = £800
- Control Unit = £200
- Copper pipes = £200
- Copper Fittings = £100
- Labour = £1000
TOTAL = £6000
Factors that may increase this price are:
- East/west roof – additional plumbing and equipment required.
- Combi boiler – you will have to have additional plumbing work carried out.
- Large house – more panels and larger tank required.
- Small house – less panels and smaller tank required.