You can call it what you want, but the levelized cost of generation includes plant costs and construction and maintenance costs. Cheapest is cheapest, no matter how much it runs. If your cheapest generations is solar, and it only runs during the day, then use it during the day. Ditto wind, use it when it's running good and use other sources when it's not. That's just the way grids are being managed. If your "tractor" only has to run 60% of the time, instead of 100% of the time, guess what, your tractor is going to last longer.