35% of domestic solar systems may be underperforming
Posted by Cathy Debenham on 28 January 2014 at 11:23 am
Some homeowners are getting a significantly lower return on investment from their solar panels than expected according to PassivSystems. The company found that a third of residential solar panels monitored by its home energy management systems are not generating as much electricity as promised. It also found that when owners manage their PV installations well they can perform up to 17% above the expected benchmark.
PassivSystems carried out a study on solar PV returns using its portfolio of 16,000 monitored PV systems on homes across the UK between 2010-2013. It used the data to analyse the performance of the solar panels against a range of different criteria, looking at how the installation, maintenance and monitoring activities influenced the return.
"If this under-performance is measured and well understood, it is possible to take steps to counter it," says PassivSystems professional services director Ian Rose. "This may be through improved installation practices, altered maintenance regimes, or through better education and support of the householder.
"The causes of system losses are commonly down to shading and technical faults with the inverter. However, our research identified a number of additional reasons. These include poor or incorrect wiring during installation, residual current devices (RCD) tripping (which in many cases can go unnoticed for many days or weeks), tenants inadvertently disconnecting the system and pay-as-you-go meters cutting out generation.
"This highlights that human interaction with the system, whether from interference or failure to monitor the system status, can result in significant impacts on the levels of generation achieved."
The study found that solar PV is energy efficient. However, in order for it to be financially efficient Ian Rose recommends that the system is properly monitored and managed. If not, system owners may lose hundreds if not thousands of pounds over the life of the PV system.
There are a number of monitoring systems available to help people get the best returns from their solar panels. The PassivLiving system (and others, see links below) show you how much electricity your solar system is generating versus how much your home is using. This makes it easy to choose when to turn appliances on or off so that you can use as much of your free solar electricity as possible. The more sophisticated monitoring systems let you compare your current PV generation against your anticipated generation, track the performance, view your latest meter reading online and easily download and review the data for your quarterly feed-in-tariff submission.
The implications for owners and funders of residential PV systems are clear says Ian Rose. "These are not 'fit and forget' assets, but are prone to a range of technical, human and environmental factors that can influence performance and the rate of return. To fully optimise your solar PV system, both from an environmental and a financial point of view, domestic installations need to be well managed and maintained. The right type of energy management system can pay for itself very rapidly."
More information about solar PV on YouGen
From the blogCathy Debenham
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