Why wind is not the poor relation to solar

Posted Thursday 1st of May 2014 at 12:44


Are wind turbines the poor relation to solar PV when it comes to renewable energy systems? 'Definitely not' is the loud cry from the wind turbine fraternity particularly if you are looking to install an off-grid system.

Here's a quick snapshot as to why wind is the perfect partner to solar PV.

How output from wind and solar varies with the time of yearPower during the Winter - The lower solar irradiance levels during the winter mean that power generated by solar PV panels is much reduced. In the northern hemisphere at a latitude of 50o N (London Calgary and Warsaw) daylight hours are just 8.74 hours at the winter equinox on 21 December compared to 16.5 hours on 21 June at the peak.

Power during the night - The wind keeps on blowing during the night admittedly it's often not as strong during the day. The advantage of this continuous input of energy into the battery banks is that it reduces the depth of discharge so batteries last longer - important when you think that batteries are a significant proportion of the cost of a renewable energy system.

High temperatures affect PV performance - The performance of solar panels is reduced as temperatures increases. Studies show that efficiency drops by about 0.4 % for every 10C increase in temperature. A silicon solar cell of 20% efficiency at 200C will only be 16% efficient at 300C. And because the surface of a solar panel is often black or dark blue it will absorb heat compounding the problem.

Snow and dust on the PV surface reduces efficiency - It comes as no surprise that a blanket of snow on the panels will drastically reduce PV output but a layer of dust does too. Studies have shown that the accumulated dust on the surface of photovoltaic panels reduce the system's efficiency by around 18%. This is a particular problem in deserts and arid parts of the world.

Power where space is limited - Wherever space is a premium eg met masts offshore platforms telecoms towers then there's only a certain amount of PV that can be installed. In these situations wind is often the main contributor to meeting power needs.

When you consider all of these issues as a whole and the fact that an off-grid power system has a very finite energy storage in the form of its battery bank it becomes obvious that wind power is the perfect partner for solar PV. Not only does wind energy generally contribute power during periods when solar PV is unable to do so but the higher energy density of wind means that it can often be more easily deployed.

This is why most of the off-grid power systems that we design here at Leading Edge are hybrid power systems utilising the strengths of both wind energy and solar PV to ensure that the power system is online regardless of the weather!

Contact us now to see how we can help you get the power you need when and where you need it!