Alright so do you know for sure they are doing this intentionally? They obviously rely on you to charge their tec and I know from experience that strong magick puts out a lot of energy that can act as an emp and fry electronics and take out the power nearby. I can’t manage that level of shifting but I can just imagine the energy output of such. I’ve knocked out the power to my neighborhood on accident with my experiments. I also know light is suppose to interfere with physical manifestation of energy such as that of strong shifting making it harder to accomplish. Have you tried turning the power off when these meetings and activities start and then turning it back on say an hour or two later and give them a chance to do their initial shape shifting and let the disruption that puts out settle down. If they aren’t doing it fully intentionally then that should help avoid the initial bursts of energy.
Otherwise a few things you can do would be to try and communicate with the elementals and land spirits to try and get them on your side and offer protection. Communicating with the animal spirit of the forms they take might allow you to also cut them off from that power at least when they are close to you. To them it would seem you are suddenly protected and they are likely to accept it as the will of their spirits instead of risking a large amount of trouble.
A last resort will be a direct confrontation. It is important to remember their power is largely based on fear. In fact most baneful magick except the most direct forms rely on the fear and weakness within the target whether conscious or unconscious so mastering your internal weaknesses will remove much of their power to affect you and let you have faith and power in your own magick to counter theirs. Most likely you won’t be able to harm them and they won’t be able to harm you either if you reach that level but it earns respect enough they will likely want avoid further trouble and waste of energy. So a truce where you leave them alone they leave you alone but keep in mind they might try mundane means of attack so exercise caution and use divination and communication with any friendly spirits to your advantage as well as your best judgment.
There might be other possibilities as well but those are what I got off the top of my head.