Solar tracking Systems
David Hilton looks at solar PV panels and a new innovation that tracks the sun for optimum efficiency in the popular sustainable investment
Many solar photovoltaic (PV) systems have been installed in the UK in the past few years, largely thanks to the generous incentive tariffs. But, with the devaluation of the Feed-in Tariff payments and their proposed termination early in 2019, we have been looking for ways to make the systems (or payback) more efficient. The cost of the systems may still have a small amount of flexibility once the tariffs disappear but the installation costs for a good installer will inevitably not go down.
In the UK we usually fit the solar panel array to the roof, which limits the optimisation according to the angle and the pitch of the roof (inclination). Web-based calculators such as PVGIS can help us work out the best average inclination for our geographical area, but as the sun changes its zenith in summer and winter it would certainly help if we could ‘tilt’ the array seasonally.
And this is where a ground-mounted solar tracking system is particularly beneficial. There are two types of solar tracking systems: single axis – usually an east to west arc – and dual axis, which allows the system to track eastwest and north-south to track the daily variations, as well as the seasonal variations, to optimise the efficiency.
The biggest benefit of a solar tracking system is that it offers a boost in electricity production. A single axis system generically sees a performance gain of around 25–35% and in the UK, while a dual axis tracker could add another 10% depending on how far north the system is situated.
Now, HeliomotionUK has developed a dual axis solar tracking ground-mounted ‘frame’ that uses GPS and its own bespoke software that allows the system to accurately track the sun in any location. The manufacturer calculates that a set of two PV-2000 (total 4kW), sited in the south of the UK, will produce 6,400kWh/year — or 60% more than the fixed 4kW array at 4,000kWh/year. And because a tracking solar power plant starts generating electricity much earlier in the morning (and will continue to do so until much later into the evening) than a fixed array facing south, the extra kilowatt hours produced by a tracker happen during the peaks in the consumption curve of the typical household: in the morning and in the late afternoon/early evening.
As these solar panels are mounted on a frame, there is no need to disturb the roof or potentially blight the architecture with unsightly panels. There is a cost for the frame but there are also potential installation cost savings — no scaffolding is required and there is no specialist installer required to match the installation materials to your specific roof type. It can be assembled by a confident DIYer but the electrics will need to be planned and installed by a suitably qualified and competent electrical tradesperson.
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December 2018