The power needs are mainly for radio communications back home?
Or that includes navigation / propulsion / course corrections / reorientation also?
(There is not enough "solar power" that can be harvested at that distance I presume)
If we spread out the communications to be less frequent and say bring it down to essentially a heartbeat signal once a month ..would it prolong the service life. Mostly for emotional reasons at that point :)
Voyager 2 is approximately 20 billion km from the Sun
Earth is approximately 150 million km from the Sun
Sunlight intensity falls off with the square of distance (ignoring any additional small losses from space dust / scattering from gases etc), so twice the distance = a quarter the solar flux. At the Earth it's ~1361 watts per square meter.
Voyager 2 is approximately 133 times further from the Sun than Earth is, which means it receives optimistically 1361 / (133^2) = 0.07694 watts per square meter.
I found a JPL article [1] that says the RTG onboard Voyager produces 40% less power than it did at launch, and the Wikipedia article [2] says it produced 470W at launch, which means it makes ~280W now.
Wikipedia [3] suggests the solar panels available at the time of Voyager's launch in the late 1970s could convert ~10% of incoming solar power to electricity. Modern panels bring that up to 30% but the designers of Voyager did not have access to time travel.
So at present distance Voyager would need approximately 36000 square meters of solar panel to produce the same amount of power.
There have already been some questionable football field size comparisons in this discussion thread, but in this case the comparison might add intuition—that is about 7 American football fields worth of solar panels.
It might be possible to use the remaining electrical heaters as some kind of crude thermal battery (assuming they have any heaters still running, they already shut down the heaters for most of the scientific experiments).
Simply turn the heaters off before transmitting and keep any transmission periods short enough that the electronics don't get too cold.
JPL probably have a bunch of tricks like this ready for when power levels drop. That 2025 estimate is 10 years old and I'd be surprised if it's final.
