Help and Advice

Get quick answers to your questions on Solar Panels, Heat Pumps, Battery Storage and EV Chargers below

Choose your FAQ section:

Solar Panels

Q
How does a solar panel system work?
A

When the sun shines on solar PV (photovoltaic) panels, they automatically generate direct current (DC) electricity. This electricity is then fed into an ‘inverter’ which transforms it into alternating current (AC) which you can use in the home or at work.

Q
How much do solar panels cost?
A

A typical domestic solar panel system now costs in the region of £5,000 to £6,000 including VAT at 5%.

Commercial solar PV systems usually start around £10,000 + VAT.

Q
How much of the solar electricity will I use?
A

Most homes consume about 30% of the electricity generated by the panels. The remaining 70% is exported to the national grid. If you install battery storage as well, you can capture about 80% of the solar electricity, with only 20% escaping to the grid.

Commercial customers usually have much higher energy needs, and solar panel systems are sized so that between 50% and 100% of the solar electricity is consumed on site.

Q
How long does it take to install solar panels?
A

It normally takes no longer than a day to install a domestic solar panel system. Smaller systems may only take half a day. If you have both solar panels and battery storage installed, the project may run over into a second day.

Larger, roof-top, commercial solar PV installations can take anywhere from a couple of days to four weeks or longer, depending on the number of panels and the type of roof covering.

Q
Can I charge my electric car with solar panels?
A

Yes you can. If your electric car is plugged into its charging point at the same time as the sun is shining on your panels, then some of the solar electricity will flow into your car’s battery. You can even get EV charging points that can be set to charge your car only when there is sufficient solar electricity available – guaranteed environmentally friendly motoring at zero cost.

Q
How long do solar panels last?
A

Solar panels are incredibly robust and should last at least 25 years, most likely considerably longer. They gradually degrade over time, generating a little less electricity as each year passes.

Q
What kind of warranties do solar panels come with?
A

Solar panels generally have two warranties:

First, a product warranty. This is typically 10-12 years, though can be as long as 25 years for the more expensive panels. If the panel stops working within the warranty period, it will be replaced, fixed, or you will receive financial compensation.

Second, a performance warranty. Most manufacturers guarantee their panels will operate at at least 80% of their original capacity after 25 years. Some specify over 90%.

Q
Can I still get solar panels if my roof is shaded?
A

Yes. While it’s true shading from trees or chimneys will lower the electrical output of a solar panel, there are technologies available that help mitigate the effect of shading. One of the best solutions on the market is made by SolarEdge: a power optimiser is installed on the back of each panel, making every panel’s output independent of all the other panels in the array. This increases overall solar generation considerably.

Q
How do solar panels work with battery storage?
A

You normally generate more solar electricity than you need at any given moment. If you have battery storage put in as well, the battery keeps an eye on the solar generation, and, as soon as it sees surplus solar electricity, it starts charging itself with that surplus. The stored solar electricity then discharges automatically when you need it. In this way, you capture and use a much higher percentage of your solar electricity and much less flows out to the national grid.

Q
Can solar PV panels heat my water?
A

In many cases, yes. If you have a hot water cylinder with an immersion element, excess solar electricity can be automatically diverted to turn on the immersion and heat your water. A popular device to achieve this is called the Solar iBoost. It’s inexpensive to install and pays for itself very quickly

Q
Where are solar panels made?
A

The vast bulk of solar panels are now made in Asia by large-scale, specialist companies. Typical manufacturing countries include China, South Korea, Taiwan and Singapore. So-called ‘Tier 1’ panels are made in huge quantities and to exacting standards.

Q
What’s the difference between solar PV and solar thermal panels?
A

Solar PV panels generate electricity. Solar thermal panels, on the other hand, produce hot water only (not electricity). In recent years, solar thermal panels have become less attractive, as heat pumps have grown in popularity as a way of heating both your home and water.

Air Source Heat Pumps

Q
How do air source heat pumps work?
A

Air source heat pumps extract heat energy from the air outside of your home and use it to heat up your radiators or underfloor heating system. They also heat your water.

Although they require electricity to work, they provide more heat energy than the electrical energy they consume.

Q
What equipment in the home do they replace?
A

An air source heat pump replaces your boiler. Your current boiler will probably run on oil, LPG, gas, electricity or pellets. The new heat pump connects into the same pipework as your old boiler, though some adjustments may need to be made.

Q
How do I know if my home is suitable for a heat pump?
A

Your home needs to be well insulated for an air source heat pump to work efficiently. As part of our service, we will carry out a full technical survey in order to establish if a heat pump makes sense for you. Sometimes additional works are required, such as replacing your main water cylinder, upgrading the pipework, or changing your radiators.

Q
How much do air source heat pumps cost?
A

A rough, ball-park figure to supply and install a domestic air source heat pump is £10,000 to £14,000 inc. VAT. The cost can be lower for small systems and higher for large installations. The government helps you mitigate this upfront cost via the Renewable Heat Incentive.

Q
What is the Renewable Heat Incentive Grant?
A

The Renewable Heat Incentive, or RHI, is a government grant that you can apply for if you have an air source heat pump installed. The grant is paid 4 times a year, for a total of 7 years. You receive the grant as long as your heat pump is working properly and generating heat. The heat pump must have a Microgeneration Certification Scheme (MCS) certificate. We can work out how much your grant would be or you can use the official government RHI calculator (https://renewable-heat-calculator.service.gov.uk/Default.aspx).

Q
How long do they take to install?
A

A typical, single-unit air source heat pump takes about 3-5 days to install. The installation can take a little longer if additional works are required, such as a replacement water cylinder or radiators.

Q
How long do heat pumps last?
A

Most air source heat pumps are warrantied for 5-7 years. The warranties are often dependent on the heat pump being serviced once a year. Well-maintained heat pumps should last at least 15-20 years or longer.

Q
Do air source heat pumps need maintaining?
A

Heat pumps are quite robust and generally don’t need much maintenance. However, some heat pumps do require an annual service in order to keep the warranty valid. It’s a good idea to have a professional heat pump engineer check your system either once a year or once every two years.

Q
Do heat pumps work when the temperature is below zero?
A

Yes they do! They can work down to about -20 °C. You may be wondering how that’s possible, as it might seem like below zero the air won’t have any energy in it. The answer lies in the fact that the Celsius temperature scale is artificial. True temperature is measured in Kelvin (not Celsius) and the coldest possible temperature – containing no heat energy at all – is zero degrees Kelvin which is a mighty -273.15 °C!

Battery Storage

Q
What is battery storage?
A

Battery storage allows you to store electricity to use later on in the day. Most batteries nowadays are made of lithium-ion.

Q
How does battery storage work with solar panels?
A

Battery storage is normally installed for customers who already have, or are planning to get, a solar panel system. Why? Because in many cases you don’t use all the solar electricity you generate. That precious, excess electricity can be stored in a battery and then discharged to the home or office when you need it later in the day or at night.

Q
Which battery storage brands are popular?
A

A very popular battery for home or commercial use is the Tesla Powerwall. It can store 13.5 kWh, or units, of electricity.

Other brands include Alpha Smile, Sonnen, LG, Powervault and SolaX. There are several other makes, too, and we install all the makes and models currently available in the UK.

Q
How long does battery storage last?
A

Over time, lithium-ion batteries gradually degrade. The result? They can no longer hold 100% of their charge. For example, a battery that can store 10 kWh in Year 1 might only be able to store 9.5 kWh after a couple of years. Most decent batteries should last for about 10 years with acceptable degradation. Some of the better makes should have a useful lifetime of about 15 years.

Q
What kind of warranties does battery storage come with?
A

Some of the cheaper batteries are warrantied for 5 years, though most now offer 10-year warranties. There are usually various components to the warranty, for example:

• Degradation / Energy retention
• Number of cycles
• Aggregate energy throughput
• The way the battery is used (known as ‘application’)

It can get a bit confusing comparing warranties, as manufacturers display the data in different ways. Please let us know if you need anything explaining.

Q
Can you charge batteries with off-peak electricity?
A

Yes. For example, you might be on an electricity tariff like Octopus Go that offers a peak rate of about 20p per kWh and an off-peak rate of 5p per kWh. With battery storage, you can fill the battery at night with electricity costing you 5p, and then automatically have the battery discharge the electricity during the day when you would normally be paying 20p. All that night-time stored energy used during the day saves you 15p per kWh!

Q
What’s the difference between AC-coupled and DC-coupled batteries?
A

An AC-coupled battery like the Tesla Powerwall connects directly to your fuse box. It’s completely independent of any other technologies installed in your home or workplace.

On the other hand, a DC-coupled battery connects to an ‘inverter’ which is also used by your solar panel system. So you can only have a DC-coupled battery if you also have solar PV panels.

Which approach is best? We would generally recommend AC-coupled batteries for complete flexibility in the future. For example, if your inverter fails in a DC-coupled system, then neither your solar panels nor battery will work.

Electric Car Chargers

Q
What is an electric car charger?
A

An electric car charger, or EV charging point, is an electrical device that allows you to charge your electric car at home. You connect the charging point to your car’s socket with a cable in order to charge the car’s battery. The charger is usually installed in your garage or on an external wall.

Q
Do I need an electric car charger?
A

You can charge your car by plugging one end of a cable into your car’s charging socket and the other end into a standard 3-pin socket. In this way, you don’t need to get a dedicated charging point installed, though you will need a special cable. The drawback of charging an EV via a 3-pin socket is that it’s very slow.

We recommend having a proper electric car charger installed instead. You will then be able to charge about three times more quickly, and the charging cable is locked in place, making the whole charging process safer.

Q
How does a car charger work?
A

A car charger allows electricity to flow from your house into your car in order to charge its battery. The charger itself is connected to your fuse box. Basically, the charger is a high-powered socket that has one specific function: to provide up to 7.4 kW of power to your electric car’s battery.

Q
What’s the difference between tethered and untethered chargers?
A

A tethered charger has a cable permanently attached. When you park your car, you simply grab the cable and plug it into your car’s charging socket.

An untethered charger – also known as a universal or socketed charger – doesn’t have a cable permanently attached. When you arrive home, you would normally get the cable out of your boot, plug one end into the charging point and the other end into your car.

Q
Can I charge my car with solar electricity?
A

If you have both solar PV panels and an EV charging point, you can charge your car with free electricity from the sun. Your car needs to be plugged into its charger while the sun is shining.

You can even get charging points, like the Myenergi Zappi, which have a ‘solar mode’, guaranteeing your car will only be charged when there is surplus solar electricity available.

Q
Do you need to install an earth rod?
A

Electric car charging points are often installed externally and require special earthing protection in order to comply with the regulations. This protection is provided in one of three ways: (i) earth protection built into the charging unit itself, (ii) connecting the charger to an earth rod, or (iii) installing a ‘connection centre’ that sits between the charger and your fuse box. So you only need an earth rod if the charging point doesn’t have protection built in, or if there isn’t room for a connection centre like the ones made by matt:e.

Q
How much do electric car chargers cost?
A

Car chargers generally cost between £700 and £1,500 including installation. These prices include the government grant of £350, assuming you are eligible.

Q
Is there a grant?
A

Yes there is. It’s currently £350 off the total cost of the charger and installation including VAT. To be eligible, the main criteria are off-street parking and to have, or be getting, an electric car soon. Full eligibility criteria can be found on the government website (https://www.gov.uk/government/publications/customer-guidance-electric-vehicle-homecharge-scheme/electric-vehicle-homecharge-scheme-guidance-for-customers).

Q
What are the best makes?
A

The quality and features of EV chargers are improving all the time. Many of the latest models allow solar charging, have built-in earth protection, can be programmed to work with off-peak tariffs, and provide lots of data via a smartphone or tablet app.

Our most popular charger is the Zappi, made by Myenergi, which can also connect to other home energy devices from the Myenergi eco-system. Other brands and models we install include EO Mini Pro 2, Ohme Home Pro and Andersen. Interested in another make? Just let us know.

Q
How long does it take to install a charger?
A

EV chargers are generally quick to install. It normally takes no more than a morning. If the cable run between the charger and the fuse box is particularly long or complex, the installation can take a whole day.

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