One Third of Domestic Solar Systems may be Underperforming

35% of our domestic solar systems might not be reaching their full potential, but solutions are at hand.

rural solar pv

Many homeowners are achieving much lower returns on their investments in domestic solar systems than expected, according to PassivSystems. The company discovered that a third of domestic solar panels monitored using its home energy management systems are not generating the amount of electricity that was promised. Also, the company discovered that when systems are well-managed by the homeowner, solar PV installations are able to work up to 17% better than expected.

Using a sample of 16,000 monitored domestic solar systems, PassivSystems carried out its study on solar PV returns between 2010 and 2013. The data was used to study the performance of the panels against certain criteria to discern the influence of installation, maintenance, and monitoring activities on returns.

PassivSystems professional services director, Ian Rose, said: ”If this under-performance is measured and well understood, it is possible to take steps to counter it. 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.”

Solar energy was confirmed to be energy efficient by the study, but for it to be financially worthwhile it recommends that the system is monitored and managed properly. Hundreds to thousands of pounds could be lost over the lifetime of domestic solar systems if good care is not taken to ensure they are working properly.

There are various monitoring systems available to help people to get the best from their domestic solar systems. The PassivLiving System is just one, and it shows you how much electricity your system is generating against how much you actually use. This makes it simple to decide when to switch appliances on or off so as to make the most of the free solar power. The more complex systems will allow you to compare between current PV generation and anticipated generation, track the system’s performance, view meter readings online, and download and review data.

Ian Rose concludes by saying: “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.”

Image by Richard Dorrell

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