Solar panels
Solar panels
We’ve installed solar panels on over 900 homes in partnership with Derby City Council, who provided over £6million in funding.
They have mainly been fitted to bungalows and ground floor flats to benefit elderly and disabled tenants. Some systems have been installed to blocks of flats with large roofs, with the electricity powering ground floor flats and communal areas.
Not all council properties are suitable to have solar panels fitted. Generally, we install them on south-facing roofs, as they receive the right amount of sunlight to work properly. We also consider the pitch of the roof and the roof construction to make sure it will be able to hold the weight of the panels.
| Total kWh generated | 1,989,214.7 |
|---|---|
| Carbon savings in tonnes | 779.8 |
| Equivalent cost of electricity | £596,764 |
Carbon savings calculated at 392g CO2 per kWh based on values and assumptions in this blog post. Cost of electricity based on average domestic electricity price of 30p per kWh.
Electricity use
Having solar panels installed on your roof does not necessarily mean that you will have no electricity bills. When your panels are producing electricity, the electricity produced by the panels will always be used first. Any extra electricity needed will be charged as normal from your supplier via your electricity meter.
Making the most of your solar panels
If you want to save as much money as possible, take advantage of the free electricity produced by the panels:
- Try to use appliances, like washing machines, during daylight when solar panels are producing electricity
- Only use one major appliance at a time, so that you are taking full advantage of the free electricity
Any electricity that is not used will go back on to the national grid automatically through your electricity meter.
Maintenance and safety
Solar panels require very little maintenance, from time-to-time contractors or our Repairs team may need to check or service them. Please make sure you do not block access to the inverter and generation meter or tamper with any of the equipment that has been installed. Only a qualified Solar PV trained electrician should work on the equipment installed.
If your home is fitted with Photovoltaic (PV) solar panels, you will have some electrical control equipment installed in the loft:
- Do not interfere with the electrical equipment.
- Do not switch off your solar PV panels at either of the isolation switches next to your fuse box or in the loft unless you are instructed to do so, or in an emergency.
- It is important that air can move freely around the control equipment. so never store items or boxes near it.
The panels and control equipment generate high voltage electricity that can be dangerous if interfered with.
The panels will switch off automatically if there is a power cut or the main electricity supply to the property is switched off. You do not need to turn the isolation switches back on.
The panels on the roof are fragile and damaged easily. Make sure anyone working on the roof, such as television aerial or satellite dish installers are aware of the risks. Only use registered, qualified installers as you may be liable for any damage they cause to the panels or equipment.
Please report any damage to the panels or equipment to Derby Homes as soon as you are aware of it. You can do this on MyAccount.
Solar panels in your home
Why your home has had Solar Panels fitted
Your home is connected to the solar panels on the roof of your property. Over 900 Derby Homes properties have had solar panels fitted to their roofs. They have mainly been fitted to bungalows and ground floor flats.
Not all of our properties were suitable to have solar panels fitted. The panels were generally fitted on south facing roofs as they would receive the right amount of sunlight to work properly. We also had to look at the pitch of the roof and the roof construction to make sure it
could hold the weight of the panels.
How your Solar panels work
The panels work by taking energy from sunlight and turning it into electricity. They only work and produce electricity during daylight hours. The electricity they produce is yours to use free of charge. If you don’t use it all, it will flow back through your electricity meter back on to the
national grid.
The electricity produced is a direct current. In your loft or in your outside meter store there is an inverter that converts the electricity into an alternating current, so that the electricity can be used in your home. There are also isolation switches near your consumer unit (electrical fuse box) and in your loft. This is so the panels can be switched off if any work needs to be done to any of the equipment or in your loft. There is also a generation meter in your loft that records all of the electricity that is generated and sends details of this electronically to a monitoring company.
This diagram shows you how the system is connected in your home:
DC - Direct Current
AC - Alternating Current
The amount of electricity generated by the panels will vary over the year. The hours of daylight are shorter in the winter than the summer months, so less electricity per day will be generated. The intensity of the daylight will also affect how much electricity is generated. It is not hot days, but brighter days that will produce the most electricity. Even on a cloudy day, some electricity will be generated. Only on dark, rainy days are the panels unlikely to produce very little or no electricity.
What you need to do
Having Solar panels installed on your roof does not mean that all your electricity is free. You will still receive a bill from your electricity supplier for any electricity you still use that is supplied by them.
When your panels are producing electricity, the electricity produced by the panels will always be used first. Any extra electricity needed will be charged as normal from your electricity supplier via your electricity meter.
If you want to save as much money as possible and take advantage of the free electricity produced by the panels, you need to decide to use appliances when you know the panels are likely to be producing electricity. Try to use one major appliance at a time, so that you are taking full advantage of the free electricity.
However, you do not need to change your current lifestyle if you don’t want to. Any electricity generated by the panels will automatically supply any appliances you have on all the time including timers, your fridge/freezer and items left on standby. So even if you don’t do anything, you will still benefit from this free electricity. Any electricity that is not used will go back on to the national grid automatically through your electricity meter.
Solar panels require very little maintenance, but from time to time, contractors or Derby Homes Repairs Team may need to check or service them. Please make sure that you do not block access to the inverter and generation meter and do not tamper with any of the equipment that has been installed. Only a qualified Solar PV trained electrician should work on the equipment installed.
Please do not switch off your solar PV panels at either of the isolation switches by your consumer unit (fuse box) or in the loft unless you are instructed to do so, or if there is an emergency. The solar PV panels will switch off automatically if there is a power cut or the main electricity supply to the property is switched off. The isolation switches do not need to be re-switched on or off manually.
Photovoltaic systems
Photovoltaic (PV) systems work by taking energy from sunlight and converting it to electricity.
The PV cells are made from two thin slices of chemically treated silicon, placed under a thin layer of glass (see diagram). When sunlight shines onto the PV cell, the reaction of the chemicals creates electrons that are used to form an electric current. This process is called the ‘photovoltaic effect’. The cells require virtually no maintenance and can last for up to 40 years.
An individual solar cell only generates around 0.5V of electricity, so a collection of cells are fixed together to form a solar panel which will generate between 80 and 230kWp of power. A number of panels are fitted to a property on a southerly facing roof at an angle of between 30º and 50º, where they will receive maximum sunlight.
PV systems can also be installed on south-easterly and south-westerly facing properties, although they will be about 5% less efficient than those fitted on a southerly facing roof. We do not fit panels on northerly facing properties as they would not receive the right amount of sunlight to generate enough electricity for the property.
The electricity generated is called a ‘direct current’. This has to be converted to an ‘alternating current’ before it can be used to power electrical items or be transferred onto the national energy grid. This conversion is done using an inverter.
A well installed PV system will produce between 750kWh and 850kWh of ‘alternating current’ electricity every year, Depending on the size of the installation.
The panels and the inverter account for most of the cost of installing a PV system but there are other things needed to make sure the system works safely, reliably and to current electrical regulations.
A grid connected PV system
Grid-connected PV systems make use of the existing mains electricity grid. They are simpler in design and easier to install than ‘off grid’ systems. The electricity produced during the daytime can either be used by the property occupier or directed back into the national grid. At night, or on dark days when the panels don’t produce enough power, electricity is supplied to the property using the normal utility company grid system.
