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What can we do about our neighbours’ trees reducing the efficiency of our solar panels?

Property Clinic: We have been told overgrown leylandii trees would reduce panels’ efficiency by 20 to 30 per cent

‘We were hoping to install solar panels on the roof of our bungalow, which has a good southerly orientation’
‘We were hoping to install solar panels on the roof of our bungalow, which has a good southerly orientation’

We were hoping to install solar panels on the roof of our bungalow, which has a good southerly orientation. However, we have been told that because of our neighbours’ overgrown leylandii trees, the efficiency of the panels will be reduced by up to 20 or 30 per cent. What can we do?

The issue of high trees or other obstacles that reduce natural light to solar panels is a concern to many householders contemplating this system as a renewable energy option. Many householders, who wish to invest in renewable energy, and whose options are limited to solar panels, roof mounted or otherwise, find, to their dismay, that the potential for energy generation is seriously compromised due to nearby high trees.

It is now a requirement under the building regulations that new buildings have a specific quota of energy from renewable sources. However, to date, there is no specific legislation or regulations in relation to overshadowing by trees. The relevant Government departments and relevant professional bodies may need to initiate a debate and consider guidelines that enable property owners to understand, come to terms with, and address this new reality in our attempts to combat climate change. Legislation may be necessary. Some jurisdictions already have legislation that prohibits or limits the planting of new trees that reduce natural light to existing solar panels.

Photovoltaic (PV) solar panels are highly sensitive to minor changes in natural light intensity. Having recently carried out a monitoring exercise on two such systems, I was surprised at the high degree of sensitivity. So, you are right to be concerned.

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You should explain your dilemma to your neightbour without implying that you have any right to expect them to take action.

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In the circumstances, I think your best option is to discuss your plans with your neighbours. You should understand from the outset that you have little or no rights in relation to the trees. Leylandii trees are problematic in many respects in residential areas. However, they are your neighbours’ property. Your rights are limited to matters such as the parts of branches overhanging the boundary of your property or a significant reduction in natural light to your house. This latter issue applies to a right to light established over many years and addressing it requires documented evidence of the level of reduction. Nearby trees causing a reduction in natural light intensity to solar panels are a separate issue.

Therefore, in discussing the issue with your neighbours, you should explain your dilemma, without implying that you have any right to expect them to take action. Involve them in discussion and ask if they have any suggestions for a solution concerning the trees. By appealing to their sense of goodwill it may be possible to get them to at least agree to reducing the height of the trees. You may consider offering to meet part or all of the cost of this work if you believe this will enable you to achieve your objective.

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In the absence of regulation or guidelines it is in everyone’s interest that there is co-operation between neighbours in these situations. Householders who try to reduce their carbon emissions by installing renewable energy systems, including solar panels, are not only improving their immediate neighbourhood environment but are making their personal contribution to the reduction of global carbon emissions.

Let’s hope your neighbours see the benefits of your proposed contribution and co-operate with you.

Patrick Shine is a chartered geomatics surveyor, a chartered civil engineer and a member of Society of Chartered Surveyors Ireland

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