We’ve written before about the possibilities of domestic ground mounted solar panels, and now there is an exciting development that could make these types of installation even more affordable. By essentially using the same mounting systems we use for flat roof PV, we can install Van der Valk ground mounted solar panels to cut time and costs for our clients.
Let’s take a look at how it works.
When should you consider ground mounted PV?
Ground mounted solar PV is great if you don’t have a suitable roof - provided you have enough unshaded land. On the ground, you can choose the optimum orientation to maximise how much energy you generate, which you can’t do with an existing roof.
To make financial sense, a ground mount needs to be at least 10kWp for a single phase property, or 20-30kWp for three phase. Your usage should be at least 10,000kWh per year.
Unlike residential rooftop PV, the regulations for ground mount arrays mean more upfront hurdles - you’ll almost certainly need planning permission and prior DNO approval.
Van der Valk ground mounting setup
Van der Valk mounting is a type of low profile frame that we usually use on commercial flat roofs (ValkPro+), but instead of the rubber mounting feet we use concrete 'mass blocks' to both elevate the system off the ground and provide ballast.
The process for installing ValkPro+ for ground mounting is as follows:
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Before installation day, the site owner needs to prepare the ground - cutting the grass, laying a groundsheet and gravel as desired.
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Our team installs the mounting frame on concrete mass blocks. For south-facing systems, a row spacing of 1.5m leaves about 0.5m for shading between each row of panels. East-west mounting uses all the space without gaps.
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We fit the solar panels to the frame - the panels are usually pitched at 10 degrees.
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The electrics are connected up. The inverter is either installed in a GRP (glass-reinforced plastic) kiosk, which may not be ideal if it will get too hot, or in the building where the solar power will be used, if the DC cable run is under 100m. We assess the best solution on a case-by-case basis.
The installation process is visualised in the video below:
Van der Valk vs P-rack for ground mount
The standard method for installing ground mounts, which we have used in the past, is with K2 P-racks. These large metal frames support panels in groups of up to 16 and have to be firmly anchored in the ground.
There are a few key differences to consider between ground mounting with Van der Valk and P-rack:
- Inverter placement. P-racks give enough space to conveniently place the inverter behind the panels in their shade, while ValkPro+’s low profile means you need a separate enclosure or DC cable run to the nearest building.
- Ease of installation. One of the main advantages of ValkPro+ is how quick it is to fit - Van der Valk estimates 4-5 minutes per panel. As no ground penetrations are needed, the whole process is much simpler and therefore cheaper.
- Output. Solar panels on ValkPro+ are mounted at a 10 degree angle vs 25 degrees on P-rack. This means the ValkPro+ output is about 7% lower when facing south, but 2% higher for east-west arrays.
- Land usage. If multiple rows of panels are required to best utilise the available area, then the lower pitch ValkPro+ system is more space efficient since you need less of a gap between rows to avoid shading (see ‘optimising mounting angle’ here). P-racks raise the panel up higher, which means the space underneath is available for limited use (you could graze sheep or encourage wildflowers), while the small gaps under ValkPro+ could potentially be attractive homes for pests.
- Cost. Van der Valk ground mounting is approximately 15-20% cheaper than P-rack (see below).
Example costs
|
System size |
VDV ballpark price (inc. 0% VAT) |
P-rack ballpark price (inc. 0% VAT) |
|
10 kWp |
£19,000 |
£27,000 |
|
20 kWp |
£29,000 |
£40,000 |
|
30 kWp |
£39,000 |
£51,000 |
Costs exclude groundworks for cable runs and preparing ground for PV array. Assumes JA Solar 330W all black panels and standard string inverter.
Next steps
If you’d like to talk to us more about ground mount or other forms of PV, please give us a ring on 0118 951 4490 or email info@spiritenergy.co.uk.
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