Energy Saving with Solar Thermal Panels & Loxone

When you hear about ‘solar’ you’ll probably think of photovoltaic panels that generate electricity (the one the government rather annoyingly cut the feed-in tariff on…). But there’s another form of solar, one that’s been around for a lot longer – ‘solar thermal energy’ (or ‘STE’). As with PV, light and heat powers solar thermal systems, but what controls them? Well, why not a Loxone Miniserver? That’s what one of our Spanish partners Econergy say anyway.

One of the reasons STE has never been as popular as PV is that it is hard to monitor how much money your panels actually save you on your utility bills. This project very nicely demonstrates how Loxone can change this by controlling and monitoring your solar thermal system. The project which we we’ll take a closer look at is a community installation, with the solar panels fitted to the roof of a multi-apartment complex. But the principle behind it is the same, no matter what size the installation is or whether it is in the Spain or the UK. And in fact even in the UK thermal solar panels can significantly reduce your energy bills for heating hot water all year round.

About the installation

This 32 apartment block, in the area of L’Hospitalet de Llobregat (south west Barcelona), is a relatively new build, having been up for just over a year. All of the hot water and even the heating in all 32 flats is provided by STE.

The installation has two 2000 litre thermal stores, a double pump set on the primary side to draw heat from the panels on the roof and a secondary circuit that supplies the heat to the flats themselves. Of course this is a little bigger than your normal UK installation.

To manage such a large number of panels and to ensure that each panel can perform at its very peak efficiency, seven different heat exchanges are used to balance the return temperatures to seven groups of panels. The heat is then dumped into the thermal stores from where it can then be delivered to the apartments when needed. To prevent anyone from scalding themselves when having a shower, a mixing valve ensures that no matter what temperature the thermal store is at, there’s a constant water temperature being provided to occupants.

What ‘extras’ can Loxone bring?

Besides handling the basic operations of a system like this – which essentially means turning the pumps on when the panels warm up from then sun – the Miniserver can also:

• Monitor the pump run time and status to alert an engineer if a pump needs servicing or has broken down.
• Monitor and log the temperatures in all parts of the system to provide detailed performance statistics.
• Remote maintenance and changing of operating parameters, such as temperature thresholds and pump overruns.

The temperature logging and monitoring is what our partner in Spain is interested in the most, as it allows him to tweak the system to get top performance and show his client exactly how much energy is being produced.

It is the use of our particularly cost-effective 1-Wire Temperature Sensors that makes monitoring to such a high level achievable and economical and allows the property management company to keep a close eye on their return on investment, whilst of course also ensuring that the tenants always have enough hot water.

More specific technical details

• Total panel output: 48KW
• Installation of 1 x Miniserver, 1 x 1-Wire Extensions & 17 x Temperature Sensors
• Control of primary circulation through panels and secondary distribution to flats
• Optimised performance through the use of multiple feeds into thermal stores
• Tracking of temperatures in at multiple points for maximum efficiency
• Management of the outbound mixing valve to ensure constant temperatures flats

Thanks to Econergy for their hard work on the project and for telling us all about it. We hope that – even if it’s not tempted you to set up an STE heating system – this example’s gone some way to show you how flexible the Miniserver is. It can be used to control a million and one things…