The Megaflo Eco Solar PV Ready Indirect is an unvented cylinder that heats water for free by diverting surplus electricity from a home's existing or new solar PV array — no roof work and no additional installer training required beyond standard G3 unvented competency. It ships with a fully wired, pre-integrated Solar iBoost+ control unit, so surplus solar generation that would otherwise be exported to the grid is diverted straight into the cylinder's immersion heaters instead. Boiler-backed via an internal coil, it's available in 210, 250 and 300 litres, built from high-grade duplex stainless steel, and carries a 30-year warranty on the inner tank.
Free hot water
From surplus solar PV
Boiler-backed
Indirect coil
Solar iBoost+
Pre-wired controller
Safety / Regulatory — G3 Competent Person Required
Installation must be carried out by a G3 accredited competent person (Hot Water Unvented Storage Systems). Because the Solar iBoost+ controller is factory pre-wired, no training beyond standard G3 competency is required. All electrical connections must still be made by a qualified electrician. For system configuration advice, Heatrae Sadia recommend speaking to an MCS-certified installer to match the cylinder correctly to your PV array.
Info — How it works
Rather than exporting surplus solar generation to the grid at low feed-in rates, the Solar iBoost+ control unit detects excess PV output and diverts it directly to the cylinder's immersion heater(s) — turning otherwise-wasted electricity into free hot water. It's estimated that over 850,000 UK homes have solar PV installed, but only around 50% are actively using the power their panels produce before it's exported. This range is designed to close that gap without any roof-side work.
Compatibility — Two heat sources working together
Because this is the Indirect variant, the cylinder can be heated by a gas, oil, or heat-pump boiler via its internal coil, as well as by solar PV diversion through the immersion heaters — giving two low-cost or free heat sources feeding the same tank. If you need an electric-only cylinder with no boiler connection, the Direct variant (210/250/300L) is the correct choice instead.
KEY FEATURES
Fully Wired Solar iBoost+ Control Unit
The Solar iBoost+ controller ships factory pre-wired into the cylinder — plumbers and electricians don't need to source, mount, or configure a separate diverter unit. Wireless communication lets the homeowner remotely monitor energy diverted and money saved via the associated app.
Works With Any New or Existing PV Array
Compatible with any PV array, whether newly installed alongside the cylinder or already in place on the property. No roof-side work is needed to add solar diversion to an existing PV system — the controller connects at the cylinder end, keeping the installation entirely inside the property.
Coil-in-Coil Heat Exchanger
A dedicated indirect coil transfers heat from your boiler circuit to the stored water, achieving full coil heat-up in 35-49 minutes depending on cylinder size — with secondary return included as standard on every model in this range.
No Additional Installer Training Required
Beyond the standard G3 Hot Water Unvented Storage Systems qualification, no extra training is needed to install this cylinder — a meaningful advantage over separately specified diverter-and-cylinder combinations, which often carry manufacturer-specific commissioning requirements.
Internal Expansion — No External Vessel
Uses Megaflo's internal expansion system, accommodating thermal expansion within the cylinder itself. This reduces installation time and space requirement compared with cylinders that need an external expansion vessel plumbed into the system.
Duplex Stainless Steel — 30-Year Warranty
The inner vessel is high-grade duplex stainless steel for excellent corrosion resistance, backed by a 30-year warranty on the inner stainless-steel tank. KIWA approved, complying with Water Regulation 4 and Building Regulations Part G3.
TECHNICAL SPECIFICATIONS
Product code
7894916
7894917
7894918
Height (mm)
1515
1766
2081
Diameter (mm)
579
579
579
Empty weight (kg)
48
54
62
Full weight (kg)
238
282
338
Standing heat loss (kWh/24h)
1.42
1.61
1.89
Mixed water at 40°C V40 (L)
242
297
350
Coil heat-up time (min)
35.1
39.6
49.1
Coil rating (kW)
14.5
15.8
15.0
Coil surface area (m²)
0.79
0.79
0.79
Coil pressure drop (bar)
0.05
0.05
0.05
Immersions (No. x kW)
2 x 3
2 x 3
2 x 3
Heat-up - bottom immersion (min)
232
287
366
Heat-up - top immersion (min)
105
86
112
Heat-up - both immersions (min)
117
121
112
Secondary return
Yes
Yes
Yes
All connections accept 22mm outside-diameter pipe (compression nuts and olives supplied); thread rate ¾" BSP male parallel to accept standard ¾" BSP female fittings if required.
FREQUENTLY ASKED QUESTIONS
Do I need a separate solar diverter with this cylinder?
No — the Solar iBoost+ control unit ships factory-fitted and pre-wired into the cylinder. There's no need to source, mount, or wire a separate diverter device as you would with a standard cylinder plus aftermarket diverter combination.
Can this be retrofitted to a home that already has solar PV panels?
Yes — this cylinder is compatible with any existing PV array, not just newly installed systems. No roof-side work is required to add solar diversion; the cylinder connects at the electrical distribution end of the existing PV installation.
Do I need special training to install this cylinder?
No additional training is required beyond standard G3 Hot Water Unvented Storage Systems competency. For advice on matching the cylinder correctly to a specific PV array configuration, Heatrae Sadia recommend consulting an MCS-certified installer, findable via the MCS website.
Why choose Indirect rather than Direct?
Choose Indirect (this listing) if you have a gas, oil, or heat-pump boiler and want the cylinder to draw on both the boiler coil and solar-diverted immersion power — giving you two low-cost or free heating sources feeding the same tank. Choose Direct instead if you have no boiler and want the cylinder heated purely by immersion, solar-diverted or otherwise.
Can I monitor how much solar energy is being diverted?
Yes — the Solar iBoost+ control unit includes wireless communication, allowing the homeowner to remotely access energy diversion and savings data through the associated app, giving visibility into how much free hot water is being generated from surplus solar production.
