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Promote Surplus Energy With iBoost Units

Published: 03 Sep 2025 ・ Read time: 7 Mins
If you’re looking for a cost-effective solution to promote surplus energy in your home, look no further than iBoost units. These innovative devices are designed to harness excess energy generated by your solar panels and utilise it to heat water in your home.
At City Plumbing, our Renewables team is dedicated to helping homeowners, businesses, and installers make the switch to renewable energy with ease. Here we explore the benefits of using iBoost units, how they work, and why they’re a smart investment for any environmentally conscious homeowner.

What are iBoost Units & How Do iBoost Units Work?

iBoost units are devices designed to help homeowners with solar panels make the most of the excess electricity their panels generate. Instead of exporting this surplus energy back to the grid for a low rate, an iBoost unit automatically diverts it to a hot water immersion heater, providing free hot water and reducing energy bills.
Components: An iBoost system typically consists of two main parts:
  • The Sender and Clamp: This part is installed near your main electricity meter. The clamp monitors the flow of electricity in your home, detecting when your solar panels are generating more power than you are currently using.
  • The iBoost Controller: This unit is installed near your hot water tank and immersion heater. It receives a wireless signal from the Sender and, when a surplus of energy is detected, it intelligently controls and adjusts the flow of that excess energy to the immersion heater.
Functionality: The core function of an iBoost unit is to "divert" excess solar energy. It's a proportional controller, meaning it adjusts the power sent to the immersion heater to match the exact amount of excess energy available at any given moment. This ensures that only free solar energy is used for heating water, and it prevents drawing power from the grid.

What Are The Benefits of using iBoost Units?

Reduced Energy Bills: By heating your water with free solar energy, you significantly reduce your reliance on grid electricity or other fuel sources for water heating, which is often a major household energy expense.
Increased Solar Self-Consumption: It helps you use a much larger percentage of the energy your solar panels produce, making your investment in solar power more efficient and cost-effective.
Reduced Boiler Use: Heating water with solar energy means your gas or oil boiler doesn't have to work as hard, which can extend its lifespan and lower your carbon emissions.
Automatic and Intelligent: The system works automatically and responds rapidly to changes in your home's energy use and the amount of sunlight, so you don't have to manually manage it.
Programmable and Manual Boost: Most units include a timer function to work alongside your existing heating schedule, as well as a manual "boost" button for when you need to top up the hot water with grid electricity.

Buy iBoost Units at City Plumbing

City Plumbing is proud to offer a selection of iBoost products from the renowned brand, Marlec. Popular and well-regarded renewable choices, here customers can find the Marlec Solar iBoost+ Main Unit and Marlec Solar iBoost+ Buddy Unit. 
The Marlec Solar iBoost+ Main Unit is a industry-favourite energy diverter unit. An effective accessory for solar PV systems, this can help you maximise your savings by converting unused solar electricity into free hot water:
Core Functionality and Technology
The iBoost+ is designed to maximise the self-consumption of a solar PV system's generated electricity. It works by:
  • Wireless Communication: A "sender" unit with a clamp is installed at the main household electricity meter. This clamp non-intrusively measures the flow of electricity.
  • Intelligent Diversion: The sender unit wirelessly transmits data to the main iBoost+ controller, which is installed near the hot water cylinder. When the system detects that your solar panels are generating more electricity than the house is consuming (i.e. when you're "exporting" power back to the grid), it automatically diverts that excess energy to the immersion heater.
  • Proportional Control: The iBoost+ doesn't just switch on or off. It's a proportional controller, meaning it constantly adjusts the power being sent to the immersion heater to match the exact amount of excess energy available, from as little as 100W up to the full rating of the immersion heater (up to 3kW). This ensures that no energy is ever drawn from the grid to heat the water.
Key Features and Specifications:
  • Dual Immersion Support: A key feature of the iBoost+ is its ability to handle up to two immersion heaters. It has a "cascading load" system, which prioritises heating the top immersion heater first (as this is where hot water is drawn from) and then diverts to the second one once the first is satisfied. It also periodically checks back on the first heater to ensure the top of the tank stays hot.
  • Built-in Display: The main unit has a backlit LCD screen that provides real-time feedback and historical data. At the touch of a button, you can see:
- Real-time power diversion (e.g. "Heating by Solar 1.6kW").
- Saved energy for today, yesterday, the last 7 days, and the last 28 days.
- Total energy saved since installation.
  • Manual and Programmable Boost: The unit offers full control over your hot water supply:
- Manual Boost: A "Boost" button allows you to manually draw power from the grid to top up the hot water. Each press adds 15 minutes, up to a maximum of two hours.
- Programmable Timer: The iBoost+ has a built-in 5/2-day timer, which can be used to set two timed boost periods per day. This allows you to schedule water heating for cloudy days or during periods of low generation. It also has separate settings for "Summer" and "Winter" to adjust to seasonal changes.
Compatibility:
  • Immersion Heaters: It's compatible with any standard immersion heater rated up to 3kW.
  • Other Renewables: While most commonly used with solar PV, it can also be used with other renewable energy sources like small-scale wind turbines, as it simply measures the power being exported from the property.
  • Battery Storage: The iBoost+ has a programmable "offset" or cut-in threshold that allows it to work in conjunction with home battery storage systems. This lets you prioritise charging your battery before diverting power to the hot water tank.
Optional "iBoost+ Buddy" Monitor:
An optional wireless display unit, the "Buddy," can be purchased separately. It provides a remote, real-time view of your system's performance and allows you to control the "Boost" function from anywhere in the home.
Installation:
The system is designed for a relatively straightforward installation by a qualified electrician. The main unit is typically mounted near the hot water tank, while the sender and clamp are installed at the main utility meter. The wireless connection eliminates the need for running new cables through the property.

Buy iBoost+ Buddy Units at City Plumbing

The Marlec Solar iBoost+ Buddy Unit is a key accessory designed to enhance the user experience of the main Solar iBoost+ diverter. While the main iBoost+ unit is typically installed out of sight near the hot water tank (e.g. in an airing cupboard), the Buddy unit brings the system's information and controls to a more convenient location in your home.
Core Functionality
The iBoost+ Buddy is a wireless, portable display and control unit. Its primary purpose is to act as a remote monitor, giving you real-time feedback and control over your solar energy diversion system without needing to access the main unit. It communicates wirelessly with the iBoost+ controller, which in turn receives data from the clamp on your main electricity meter.
Key Features and Benefits
  • Real-time Energy Monitoring: The Buddy's most important feature is its ability to display what's happening with your home's energy in real-time. It shows you:
- Current Power Diversion: It displays a message like "Heating by Solar 1.6kW," so you know exactly how much free energy is being used to heat your water at any given moment.
- Eco-Gauge / Traffic Light System: It has an intuitive visual indicator (often described as a "traffic light" system).
  • Green Glow: Indicates that you are exporting excess energy (more than 300W) to the grid, which means the iBoost+ is actively heating your water with free solar power.
  • Red Glow: Signals that you are importing power from the grid (more than 300W), meaning you should be mindful of appliance use or that you need a "boost."
  • Amber Glow: Indicates a balanced state where consumption and generation are close to equal.
  • Remote Control: The Buddy allows you to remotely control the "Boost" function of the main iBoost+ unit.
  • One-Touch Boost: A dedicated "Boost" button on the unit allows you to add time to the hot water heating cycle, drawing power from the grid for 15-minute increments up to a maximum of two hours. This is perfect for those cloudy days or when you have a higher-than-usual hot water demand.
  • Display of Historical Savings: The Buddy unit mirrors the historical data available on the main iBoost+ unit. You can view:
- Energy saved today, yesterday, in the last 7 days, and in the last 28 days.
- The total energy (and cost) saved since the unit was installed.
  • Convenience and Portability: The wireless design means you can keep the Buddy unit on a desk, in the kitchen, or anywhere in the house where it's easy to check. This eliminates the need to go into the airing cupboard or where the main unit is installed to see if your hot water is being heated by solar.
  • Easy Setup: The unit is designed for a simple pairing procedure with the main iBoost+ controller. When first powered up, it will show "Not Bound," and a simple button combination on both units pairs them together.
  • Mains Powered: The iBoost+ Buddy comes with a mains adaptor and stand. It is not battery-powered for portability; it requires a permanent connection to a power outlet to function. This ensures it's always on and ready to provide real-time data.

Make The Switch To Renewable Energy With City Plumbing

If you’re looking to make the switch to renewable energy, why not speak to the Renewables Team at City Plumbing? Experts in the latest energy-efficient technologies, we're perfectly placed to help homes and businesses make the smooth transition to renewable technology. With a dedicated Renewables hub for homeowners, we can work with you to create a highly energy-efficient home while helping you navigate the ever-expanding world of renewable technology.
For further helpful advice and suggestions on choosing the best products for your home, take a further look at our City Plumbing website for more information.

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