Sounds solid. Keep the tank size in line with the pump’s flow rate—don’t oversize it and waste water, but make sure it holds enough for a dry spell. Pick a solar‑driven pump with a controller that can throttle the flow to match the HVAC load. Use a heat‑pump HVAC; it’ll run on the same solar array and you can use the rainwater for the chilled‑water loop. Install a small battery bank for cloudy days and set the pumps to run during peak sun. Finally, seal every joint, keep the tank clear of algae, and schedule quarterly checks—no surprises when it’s winter.

Add a pressure tank so the pump never starts on every tiny pressure drop. Put a single check valve on the discharge line to stop back‑flow if the solar panel goes down. Keep the tank off‑site with a simple access hatch for quick cleaning. Install a low‑power leak detector that trips the pump off if it senses a big drop in pressure. That keeps the system tidy and lets you catch problems before they grow.