The use of solar panels has increased dramatically in the past few years and by the end of 2014 had almost doubled compared to 2013 . This increase has been fuelled by the falling cost of purchasing and installing panels, government subsidies and the desire of companies and householders to be more environmentally-friendly.
But as take up of solar panel technology has increased householders and businesses are now considering whether their investment in solar technology could be at risk if light to the panels is blocked by a new building or even large trees on neighbouring land.
In short the answer is yes; a neighbouring landowner has the right to build on or to alter existing buildings on his land and unless the land on which the panels are situated takes the benefit of a right to light it does not matter if the light to those panels is blocked.
Can a landowner have a right to light for solar panels?
As with other rights, a right to light can be acquired by express grant or by a prescriptive right arising from 20 or more years of use.
The Law Commission carried out a review of rights to light in December 2014  (the Law Commission Report). Its preferred method of protecting solar panel rights to light was for the landowner to enter into restrictive covenants with neighbouring landowners, who would agree to bind their land with the intention of preventing disputes down the line. In practice, however, it can be very difficult for a landowner to get neighbouring landowners to agree to grant a right to light. They may simply refuse outright, not wanting to hinder possible future development of their property, or require a payment for consent making the initial investment no longer viable.
At present there is no direct case law on whether a solar panel can gain a prescriptive right to light after 20 years’ long use. In the recent case of Coventry v Lawrence  the Supreme Court held that the noise emitted from a motorcycle race track over neighbouring land established an easement after 20 years’ long use even though the noise was intermittent, suggesting that the intermittency of light might not be a hindrance to obtaining a right.
In Allen and Another v Greenwood and Another  the court held that a prescriptive right to light could be acquired by a greenhouse after more than 20 years. Usually the court bases its decision on the level of light required to, for example, illuminate a room which could be vastly different to the amount required for the efficient working of a solar panel. In this case the court gave consideration to the benefits of sunlight required for the purpose of growing plants. However Lord Justice Goff stated that in a case involving solar heating it might be possible to separate out different properties of sunlight, such as its heat from its light and to reach a different judgment.
The Law Commission Report concluded that in its opinion solar panels could not benefit from a prescriptive right to light. Whilst acknowledging that this has not yet been tested in the courts the Law Commission concluded that an aperture in a building is required through which the light is “channelled” into that building. This limits the benefit of light easements to not blocking a particular light channel. A solar panel is a different proposition as it does not have an aperture; it can receive light from all angles so any easement would have to be given in the broadest terms. A large expenditure of time and effort would be required by the parties to a dispute to determine all the possible channels of light. The Law Commission also pointed out that it would be difficult to determine the extent of the easement given that the purpose of the right would be for the landowner to harvest solar energy rather than to illuminate a room.
It is interesting to note that in the responses to the Law Commissions consultation those who mentioned solar panels were unanimously in favour of greater protection of the right to light, arguing that the legal position should be changed to encourage the use of renewable energy sources not hinder it.
A landowner who is considering installing solar panels should give due consideration to the risk that unless neighbouring landowners will agree to grant a right to light it may well have no protection should its neighbours block access to light. It is unlikely that a prescriptive right will be granted, but even if the courts do find a prescriptive right arises the requirement for 20 years use is of little help to the growing number of people purchasing solar panels now.