Hey he COMES from "East of the Darling River", over near the BIG Smoke of the East Coast of Australia and IS an Evangelist too boot, ergo HE thinks HE is the New Messiah to we, the country hicks, bumpkins and heathens, etc, etc.

Why don't you get the proper authorities involved?

@Jolanta By authorities do you mean the police, by-law enforcement officers, the fire department and lawyers? because they have all been involved over the years. This is a group of people who feel that because they have been taking something that wasn't theirs for years, they are therefore entitled to keep doing so and if I offer a solution to this problem then I am the one who is being the bad neighbour.
Something I like to think of as Christian Logic but fortunately they are not getting away with this because 20 Christians don't stand a chance in the end when they are trying to steal from a single Atheist who uses his head for more than a hat rack.

@Jolanta Been TRYING to do EXACTLY that but the E.P.A. say it is a job for the local Council, the Council says it is a job for a Law Firm or the Chamber Magistrate and by the time I managed to find my way through all their guff and twaddle it was too late in the day and everyone had closed up and gone home or to the pub, etc.
Jeez Louise, surely you know what Bureaucracy is like, don't you.

@Triphid Since our respective countries are still part of The Commonwealth and operate under British Common Law, at least for the most part, it will be a matter of either a civil suit if the religitard tries to force you to remove your tree (which predates his solar panels btw) or a criminal charge of trespass, public mischief and destruction of private property if he decides that his Lord and Savior has instructed him to chop down your tree and he takes that action.
I would strongly suggest that you send him a letter indicating that the tree is your private property and he has no right to trim or cut it down in any way and posting No Trespassing Signs would also be advised so that the charge of trespass will be clear to the police. Cameras for surveillance would also be helpful.

@SnowyOwl you need to look up "adverse possession" and take steps Immediately, by which I mean,at a minimum, a lawyerly letter sent "return receipt required" And putting up a temporary fence, with pictures, for at least 24 hours.
My family went through this with farmland & you could lose substantial rights & property!!!

@SnowyOwl Already aware and re-checked the Laws regarding Trespass and Trespassing, as per the Law " Any House, Home, etc, etc, MUST have free access from the street, road, footpath, etc, etc, TO the nearest and closest FRONT Accessway in to the dwelling, therefore ANY person/persons venturing to enter said property via a NON specified route of LEGAL access may be classed as trespassing." With my house, there is available a DIRECT path from the gate which opens inwards from the street and leads directly to the main and ONLY front entrance to the house.
There is a driveway entrance plus a fence with a gate at the side of the house BUT legally speaking no person unless so invited either at the time or by an earlier agreement can pass either through that gate or down along the driveway WITHOUT actually trespassing.
So legally and technically he or anyone else may ONLY traverse that path from the gate to the door WITHOUT my permission and to venture any further WITHOUT permission it then become trespass, except in the cases of Electricity Meter Readers and Water Meter Readers and legitimate Service Providers this is of course who have a legal right to venture from the direct route from gate to door.

@Triphid The hoops that reasonable people have to jump through because of the unreasonable actions of morons, it boggles the mind.

@AnneWimsey Thank you and rest assured that I have consulted with lawyers on the issue and currently have one ready to deal with the next action which should occur this month. It's a complicated process to stick handle through the courts and the costs will run into the tens of thousands in legal fees if we cannot resolve things amicably and like adults. So far, all of their attempts have failed and they don't want to spend the money anymore than I do, also I would rather defend an action than initiate one as they will drag things out and run up my costs if I initiate an action. If I move things to their correct location then they can try to sue me but if the correction turns out to be an improvement then they will have a hard case to try and move things back to the incorrect location.

In my honest opinion, he'd be hard pressed to plan how to take a shit and how to wipe his arse afterwards.

Actually after going through my memory with a mental fine-toothed comb, I remember that he was away on one of annual wanderings/supposedly Working Trips when the panels were installed, his then "Boarder" was the one who had the job of being home when the installers were there.

@Triphid You would think the installers would have had a clue. Just like when the installer for a satellite TV comes they will tell you where the ugly dish has to be.
Doesn't matter if you don't want it seen from the curb. Do you want to see the programs you'll be paying $$$ for or not?

Have photos already, informed him that to proceed any further he MUST get MY Written permission and a SURVEY done by a Licensed Surveyor to show that my tree actually reduces the output of his solar panels to a reasonable percentage at the EXACT and PROVEN same time EVERY day for a minimum of 12 months AND then HE may, IF proven and it satisfies a Magistrate then and only then may he payb for Registered and Licensed Arborist to TRIM the tree down correctly and to the height as designated by them BUT he MUST pay for ALL Costs incurred to BOTH parties.

Situated 2 of the spare ones in a position that covers the tree from my fence which is where he has attempted to cut it back already, should have positioned a camera there much, much earlier though come to think of it now.

@Triphid Obviously he can't be trust so please protect yourself and property as best you can. Have you done any research on the laws and what you need to do. Are old growth trees protected under the law in your area? If so, give him written and verbal warning with a witness or if you're on friendly terms with law enforcement in your area, ask them to be your witness.