This week I have noticed that the solar panels and the windmill that come with Mansion & Garden have suddenly stopped working - they no longer provide "energy" and so I have to pay bills once again. Inicially I thought that there just weren't enough solar panels in the lot, as I had made some changes to the house that would probably change the bill, so I bought some more (actually, I doubled the amount of solar panels xD). Still no effect, and the bill has the cost of a house with 0 panels, even though I had about 40...
Today, I was playing with another family whose bills were also payed by two windmills. And again, the mailman comes and puts the bill in the mailbox. I haven't played with the rest of my families that have those two objects, but I guess the same will happen, as both the solar panels (the 1200 simoloeons one) and the windmill no longer function properly.
Looking back to when they worked and comparing it with now, I have only downloaded two things (aside of CC-free lots): the buyable mailbox and trashcan (AL version), and NPC Maker Fix by Cyjon, both of which don't look like they could cause any trouble. Any ideas about why this is happening?

EDIT: Probably should have posted this in the "Help" section... oh well.

it might be that some installation files were changed.
if you have disk version of game, might replace various installation files with their disk equivalents.
if you have the Ultimate Collection, I take there is a repair option at the Origin site.

as for the section for this thread, a moderator could move it.

Seems perfectly reasonable to me that both of those could potentially screw with it. The bills are tied to the mailbox, a buyable mailbox mod could if poorly made include code it shouldn't. NPC Maker is less likely, especially since it's Cyjon, but it could still affect NPC behavior in an unknown way.

My point is, there's no way to predict logically what may cause a certain problem. Sure, sometimes you can guess and get lucky, but something seeming unrelated is no reason not to suspect it. Aside from CC being poorly made, there's also the risk of a file going wonky when unzipped or moved, and the fact that code varies a little between installation languages. I have a mod that works perfectly predictable in every test, in every scenario I can think of, but that behaves completely unpredictably in another players game with no CC. Why? Who knows.

And yes, this does belong in help. Before posting in help, there's the game problem faq, and there's a reason it's there. Because it fixes most problems without needing the help of others. If I were you, I would back up my game and then pull any CC I installed since last time I recall it working. If that fixes it, you know it was the CC, and you can do a 50/50 with the new things to see which thing it is. If it doesn't fix it, try regenerating new user files and test it again. If you have UC, you might try repairing as mdsb said.

Nothing wrong with asking, sometimes you get lucky and someone happens to know a known culprit of the problem, but in the end you're sitting on the resources to figure it out.

I'll never understand the need of a downloadable mailbox....There is one on every residential lot, and if ever this is screwed well..the whole game is.

Two windmills only decrease about 40 on the bills and each solar panel should be 20 on the small and 40 on the large if I remember right.

You may need to sell off all of them save your game then quit and delete the cache files and try it again with new ones.

(I may be off on the amount because it took 10 small ones for the Goth lot to have no bills.)

You need them if you ever change community lots to residential. They don't get mailboxes or trashcans automatically.

True, but this is why you should start the lot off as the kind of lot you intend it to be long term.

Most times I need to use a buyable mailbox is when I have downloaded a community lot but I want it to be residential. There is no other way but to use a buyable mailbox.
It's also possible that someone might delete it without noticing or delete it without knowing how important it is to the lot- buyable mailbox is needed.

You might also want to make a row of houses on one lot with a street and want mail boxes for each house as part of the effect.

True!

I'd rather start my builds with the proper zoning. I would have no care for a downloaded community lot if it is only to switch it to residential..I would build one rather than downloading a modded mailbox that ruins my game.
But yeah! Go ahead and do bad things to your game huh..I won't stop you. lol

I would try starting a new town up and see if the green energy sources are working in the new town.I've got buyable mailboxes and my Fargor residents just recently had the letter carrier drop off a 10000$ check in the mail at their boarding house resdence on Tuesday.It's been happening like that every Tuesday or Thursday since they moved in.The OP's issue sounds like it could be a town gone corrupt if it's happening in all lots in that town.I had that happen once on my old computer without Mods and it was a corrupted town.It can also happen if you put too many green energy sources on the lot because I don't put more than 180 of them on larger lots at a time and that's what is on my apartment lot where my town's first resdents live.

@PanAm103
I had the exact. same. problem.

I downloaded the mailboxes from "Sim a Little, Dream a Lot"... my solar panels stopped working.

Ditched those and got the ones from Sophie-David here. Problem solved. Refunds started rolling in again.
I typically use the solar panels to offset my (playable) government buildings and so they have some petty cash, so it was pretty important to find a solution. I hope it helps!