When trees cause solar panels to be shaded this can bring up issues such as the rights of the respective owners and the environmental sacrifice of removing or pruning the tree.
In UK law, while we do not automatically have a legal right to sunlight on our buildings, the Citizen’s Advice Bureau states that a neighbour’s tree can be pruned if it is blocking light to a property, however, it cannot necessarily be reduced in height. The ‘right of ancient lights’ may be useful if height reduction is needed as it states that if a property has been receiving light on its windows for at least 20 years then generally a right will have been acquired to continue receiving that light. If trees grow to shade solar panels they may shade windows as well so this right can be used as a basis for a height reduction request.
Neighbours may refuse to cut trees on the grounds that there is only minimal shading and that trees absorb carbon dioxide. What is commonly not understood is that a solar array without micro-inverters can only produce as much electricity overall as its least efficient panel. So even if only one panel out of five is shaded and running at 50%, then the whole array can only produce 50% of its potential power.
When considering the loss of carbon dioxide absorption from cutting a tree, what must be considered is that fossil fuels will be used to generate the electricity lost from a shaded solar panel. The generating capacity of 5x200w solar panels in Sussex running at 50% is around 300kwh per year. Using a carbon calculator we can see that we would need to plant at least one tree every year to offset the carbon that making the lost electricity by fossil fuels produces. There is also the option of donating to the Woodlands Trust plant-a-tree project to make up for cutting one down.