At 26 years old the existing pump may be on its last legs, and replacing it ahead of failure may be less hassle than doing it in a rush if/when it fails. Whether you replace the pump now or when it fails, either way you can go ahead and buy one of those Grundfos SQ pumps so you'll be ready with the right replacement on hand. My pump, also 200 feet down the well, is 17 years old so I'm not sure when to replace it. My current pump is a 3/4 HP 230VAC model that requires something like 5000 watts to start up, so inverter operation is out of the question with my smallish PV system. I have the Grundfos SQ replacement sitting around already. I got the 1/2 HP 115VAC model. NOT the kind that can run directly off a solar panel, but it can run directly from a medium size 115VAC inverter. Due to the "soft start" feature, it only needs about 1200 watts to start up, and roughly 500 watts running. Its output at that depth is less then 3 gpm (from memory) but that's plenty if you are not going to run garden sprinklers... A low-flow showerhead is less than 3 gpm. Plus, you actually get the flow from the pressure tank, if it's big enough and the usage is short enough then the pump can replenish the tank later. When I replace the pump I want to replace the tank with an 80-gallon fiberglass model (WM23): no rust, and with a large reserve of water under pressure that can be used without even running the pump. Stored pressure is stored energy, and batteries are even more expensive!