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There are 3 main considerations when sizing your solar array. These are:
1. Your energy requirements
The most important factor in determining how many solar panels you need is to calculate your daily usage in kilowatt hours (kWh). You can determine your kWh per day value from your utility bill or by formulating a load schedule.
As a rule of thumb, in the UK you need about:
3kWh/10 panels for 2 people
4kWh/12 panels for 3 people
5kWh/14 panels for 4 people
6kWh/17 panels for 5 people
2. The sun hours where you live
The amount of sun you receive per day on average across the year varies between 3 & 5 hours depending on where you live in the UK. More sun hours will generate significantly more energy per panel.
3. Roof size and orientation
Your roof size, shape and any obstacles, will determine how many panels can be fitted to your roof. Ideally your roof will face south with a 45 degree pitch and not be shaded to make the most of the northern hemisphere sun, However this will vary depending on the time of year and is less of a factor than the number of panels your roof can accommodate.
If you have enough unobstructed outdoor space a ground mounted array may accommodate a larger array.
There are many factors affecting the power generation, measured in watts, of a solar array. The JA Solar panels used in this array have a power output of 365W in direct sunlight.
To calculate how much power the array will generate in a day, multiply the panel wattage by the number of panels by the typical day light hours in your area, so:
365W x 10 panels x 4 daylight hours = 14,600Wh or 14.6kWh
365W x 12 panels x 4 daylight hours = 17,520Wh or 17.5kWh
365W x 20 panels x 4 daylight hours = 29,200Wh or 29.2kWh
We have bundled energy storage solutions to match our solar array kits:
The 10 panel 3650W JA Solar array kit will perform optimally with the 3000VA Energy Storage kit.
The 12 panel 4380W JA Solar array kit will perform optimally with the 5000VA Energy Storage kit.
The 20 panel 7300W JA Solar array kit will perform optimally with the 8000VA Energy Storage kit.
The following information is our understanding of the planning permission requirements for solar panels. Consult your local authority for accurate advice.
For residential roof installations and outbuildings within the curtilage of the main residence, solar panels fall under "Permitted Development" if they meet the following requirements:
- Panels must not protrude above the ridgeline of the roof.
- Panels should not be higher than 200mm above the roof cladding.
- In conservation areas and world heritage sites, panels must not face or be visible from the highway.
- Panel installation should minimise the effect on the external appearance of the building.
- It is best practice to allow at least 300mm from the roof perimeter.
For ground mounted systems the conditions are more restrictive before planning permission is required and include:
- Must not be more than 4m high
- Must not exceed 9 Square metres (4-5 panels).
- Must be more than 5m from the boundary.
- In conservation areas and world heritage sites, panels must not face or be visible from the highway.
Ground mounted systems that don't meet these conditions require planning permission.
Don't be put off by making a planning application. A plan that minimises negative impacts is likely to be treated fairly.
For Solar Panel arrays with a generating maximum capacity of 3.68kW or less, your installer simply must inform the Distribution Network Operator (DNO) within 28 days of connection to the grid that a connection has been made. For systems above 3.68kW that are not harvesting energy into an Energy Storage Solution an ENA is required for connection to the grid.
Nearly all electrical work is notifiable and nearly all PV installations are electrical work.
Regarding building regulations, this is dependent on the type of installation and the preference of the local authority. For example, an In-Roof GSE system is integrated into the fabric of a building.
Installation of solar panels can touch on many areas of the building regulations including structure, fire safety, moisture, sound, ventilation, protection from falling, access and use of buildings and electrical safety.
Involving building control will ensure there are no issues when it comes to selling the property.