I've ignored maintenance costs as they are very small, and this is at 120x speed. *** Spoiler - click to reveal *** Factor in the cost of additional windmills by the rate prior to being purchased. then slow down to reap them so they do not whither before you can get to them. speed back up to let the crops mature quickly. turn it down as you plow and ready your fields. Now, you can change your clock accelerator as needed. so i basically wait for mowing jobs which you can complete in a couple minutes as opposed to sveral minutes for the other type of random quests. I kind of suck at their random quests except for mowing. in Farm Sim 15 there are 3 mowing stations. i even buy enough of the best mowing equipment to place one full set of mower and tractor to leave parked at each subsequent mowing station. you can buy anything you wish, all the best of each farm implements. now you will soon be swimming in virtual cash. go off and watch a video, read a book, play a game on another console, do whatever for a few hours.
now i have about $30 million on my xbox 360 version and about $22 million on my Xb1 version of Farm Sim 15. i ran errands and later watched a few movies.
i continue this process until i buy 4-5 windmills. Now you will start generating some decent cashflow. then buy a wind generator (the windmill-looking things). Let these panels grow money for you until you reach $1.2 million. do these solar panel purchases until you have about 5 solar panels. you may wish to turn off plant growth too as you are doing this to prevent plant withering. if you have your game time at 120 this is really $330+ every several seconds. each solar panel generates $330+ per "hour". once you generate enough money to buy a second Solar Panel do that. take batteries out or else it'll default to using wireless mode. once you change it to 120x you can also change quests to off if you wish to leave your game unattended with a wired controller in place (xbox one controller-remove battery and plug in a USB port to your Xbox one console.
go to your game settings and change the game time to 120x for time. so, purchase and place (anywhere) your solar panel. At this point you will have enough money to buy one solar panel. dont just sell through your menu but actually take them in and place them in the designated marked area to receive more money back from your sale. I forget where i read this but i had read about this money exploit where you start off by taking all of your farming equipment and tractors to the main store where you can drop off and sell your items.
Easy money exploit for Farm Sim 15: a couple years ago I played the earlier Farm Simulator 13 on Xbox 360.