Solar Diverters
Immersun Immersun
One of the original UK solar diverters — handles multiple loads (immersion + secondary). More flexible than single-load rivals for complex homes.
~£249 + installation
How it scores
Scores based on published manufacturer specifications and weighted criteria — not lab testing. Methodology.
Specifications
- Wi-Fi
- No
- Phases
- 1
- Load type
- immersion
- Max power (W)
- 3000
- Warranty
- 3
- Compatible with
- solar, battery
What I noticed
Immersun is one of the longest-standing products in the UK solar diverter space. Its main differentiator is the ability to manage two separate loads — typically an immersion heater as the primary and a secondary load (underfloor heating, towel rail) that cuts in once the primary is satisfied. This avoids wasting solar surplus when the cylinder is already fully heated.
Who it suits
Homes with a secondary resistive load that could usefully absorb surplus solar beyond what the cylinder needs — particularly relevant in summer when the cylinder heats quickly and surplus continues through the afternoon.
Watch for
No app or remote access. The dual-load setup requires two separate circuit connections. Installation is slightly more involved than single-load alternatives.
Sources — verified 4 June 2026
- 4eco / immerSUN, “immerSUN Installation and User Guide (v1.3)” — love-solar.co.uk
Immersun head-to-heads
Side-by-side scoring vs each alternative in our shortlist.
Other Solar Diverters on my shortlist
Read next
Background reading and decision-tree pages that put this product in context.
Smart Export Guarantee best rates 2026
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Stage 4: Do you need a battery?
Where the diverter sits in the storage-vs-export decision tree.
Battery storage vs solar diverter
When a diverter does most of what a battery would — for a fraction of the cost.