What is the flow rate?
The solar thermal flow rate is the speed of the fluid in the solar systems pipework. This goes from the pumping station around the collector and back to the hot water tank.
What is solar fluid?
Solar fluid is the liquid that circulates around the solar thermal panels on the roof. It is a mix of glycol and water.
It has to be resistant to freezing as it is in the outdoor panel all year round.
It also has to be resistant to very high temperatures. A sealed solar system can regularly go above the boiling point of water in the summer.
Why should I worry about flow rate?
The flow rate determines how much heat can be gathered from the sun.
Too high solar flow rate
Too high flow rate will not give the fluid enough time to heat up in the collector. This will give low temperature hot water on all but the hottest days.
Too low solar flow rate
Too low flow rate will not give the fluid enough time to gather heat from the collector. This provides very hot water but risks overheating and not getting the maximum amount of heat out of the panel.
What is the correct solar thermal flow rate?
Baxi solar systems
Baxi recommend the following flow rates:
1 collector = 2 l/min
2 collectors = 4 l/min
3 collectors = 6 l/min.
Ideal solar systems
Ideal recommend a flow rate depending on the size of the panels. This is similar to the flow rates recommended by Baxi.
Conclusion
More collectors require more flow rate to gather the heat from the sun.
A flow rate that is too low risk overheating and not getting all the available heat.
A flow rate that is too high doesn’t allow the solar fluid to heat up enough to actually heat up the hot water tank.
If you found this confusing:
If you found this confusing. Please let us know in the comments section so we can clear things up for you. We love feedback and we are trying to make the best possible website. If you don’t understand then others don’t as well.
If you found this useful:
If you found this useful maybe check some of our other pages.
- How Solar Thermal Heats Your Water Efficiently
- Solar thermal flow rate
- Solar Thermal Hot Water
- What Are The Components of a Solar Thermal System?
- What is solar thermal stagnation?
- What parts are in a solar thermal system.
- Hello deary