When it comes to specifying heating and energy solutions in our homes there is a new catch-word creeping into the conversations. The word is electro-tech, and even though it is a generic term, it is being adopted in our everyday language when discussing modern homes.
First adopted by economists and energy experts to collectively describe the global shift away from fossil fuels, and the move towards digitally driven, highly efficient, electrically based technologies, it's evolved to take into account renewable energy sources, and the electrification of our homes.
But what does it really mean for homeowners? In this article I'll break down the key categories of home-based electro-tech, how to maximise performance and functionality, and what you need to consider if you're designing a self build, renovating or extending your home.
What are the main domestic electro-tech categories?
Although electro-tech has evolved to mean almost any electrically based technology that we use in our homes, there are four main categories that stand out as ones that demonstrate the move towards a different style of home:
- Renewable energy supply: the use of green energy suppliers and the installation of solar panels to generate your own energy on site
- Heating source: the use of heat pumps instead of gas and oil boilers
- Smart homes: management of energy use through smart meters, battery storage and better controls, such as smart heating systems
- Electric vehicles: the switch away from fossil fuels to electricity by using electric vehicles, rather than diesel and petrol models
Although each of them serves different purposes – and as I'll come on to explain, can operate independently – the over-arching single power supply and management is where the potential value can lie. But, it's also where the risks can become apparent if you don't properly design and specify your electro-tech home
Pros and cons of an electro-tech home
Aside from the ecological advantage of reducing the need for fossil fuels, one of the the main advantage of electro-tech is that everything is connected back to your home distribution board. The fact it runs on one type of energy source, makes it potentially easier to control and manage more effectively.
Instead of juggling several supplies of power, such as gas, electric and even oil or LPG, the electricity supply coming into the home will then deliver energy and power to all parts of the home via one output source.
Even if you have solar PV panels then they too will be wired to a solar panel inverter which converts the direct current (DC) to a 230v alternating current (AC), which is also then connected to the distribution board.
A solar battery store will also be connected to the distribution board via an inverter – often the same one that manages the PV generation. Your EV charger will also be connected to the main supply and distribution board, although it could be done in a more complicated way.
In essence, you can picture the distribution board a bit like the central hub of a bicycle wheel where all the spokes – the electro-tech – join back to it.
Requirements for an efficient electro-tech set-up
On the flip side of the coin, however, the potential risk of electro-tech is that although the singular approach can streamline everything, making sure your home can handle it is another.
Most homes have a 230v single phase electricity supply and they will have a limited load capability, often 80Amps or 100Amps. If it is lower than that, then you should speak to your supplier, or the Distribution Network Operator (DNO), to see if you can get a bigger supply, as 100 Amps is about as low as you really want to go.
In real terms, this means that you can only run 18kW or 23kW total load at any one time. Exceed this and the home will overload and the supply will trip off.
To put the load vs supply into perspective, we need to look at what the likely maximum load could be in the home to help you understand what is required.
As an example, when considering just your kitchen appliances, an average oven uses 3kW, each plate on the hob is around 1.5kW, the washing machine (while heating up) uses 3 kW, a tumble dryer is between 1-5kW, the kettle 2kW and a microwave 1kW.
An air source heat pump will use between 2-5kW, the electric immersion in the hot water cylinder also draws 3kW, and an electric shower between 6kW and 8kW. An EV charger draws 7kW.
Then, as well as the bigger load appliances, you will also have a lot of background loads such as lights, computers, games, TV, chargers etc that will also add up.
If you use a combination of these appliances, plus background load and it all adds up to more than the load capacity (18kW to 23kW,) then the risk is the home electricity supply could overload and trip off.
The important of smart home tech
Although none of the appliances and technologies actually need the other systems in order to work, but it often makes sense to control them to work in tandem with each other.
As well as streamlining the amount of work the homeowner has to do to get each part working, adopting a smart home approach can also help prevent the biggest risk – overload on your electricity supply.
Many management software systems will manage the maximum load and prioritise what is most important. So for example, if it is important that the car gets charged then the software will turn off other, lower-priority appliances, or turn down the car charger output for the five minutes that the kettle is boiling. You set the priority; the software manages it.
However, there is still work to be done in this field, and most manufacturers make their own controls, often with their own logic and algorithms. It can therefore be difficult to find different technologies that can ‘talk’ to each other if they are made by different manufacturers.
It can often be enough to have simple controls that only turn appliances on or off, but in the case that the appliance can modulate, then you need the controls to be able to turn the appliance up and down rather than simply on or off.
As a result of the move towards electro-tech homes, it is becoming more common though that many manufacturers now have agreements with software creators that allow the different technologies to be fully managed by third party controls.
Preparing for an electro-tech home
The key trick to getting your home's electro-tech right, and functioning without problems, means knowing in advance how much power you will need to use.
As a home renovator or self builder, it is very important to know the full list of products that you would ultimately like to have in your home. This way, you can be sure to install a controls platform that supports all of them.
Don’t just think about now, think into the future – even if you think it is a very distant dream. Maybe you don’t yet have an electric vehicle, but it is on the radar for the next few years?
If so, choose an EV charger that will be able to be controlled by the same software. If you have solar power, make sure that the charger can also be left in stand-by mode so that the car can be automatically topped up if you have excess generation. Many car chargers also have the facility to connect CT clamps. These guard against overloading the home.
If you are designing a self build and need to arrange for power connection, you might also want to consider investigating the option of a three phase electricity supply. This will spread heavy electrical loads across three phases, rather than one, reducing the risk of overload.
While this will be more expensive to install, it could offer some protection for the future as the electrification of homes continues.
Don't assume battery storage solves the issue of overload
“But what if I have battery storage? Doesn't that make a difference,” I hear you ask.
Battery storage does not add to the overall maximum load of the home, and it also needs to be managed. The maximum load of a battery is also limited by the solar panel inverter. Why? Because the energy stored in the battery is also DC, so it too needs to be converted in order to be used in the home.
If the same inverter is used to convert the PV generation and the battery energy, then that is limited to the size of the PV panel array. So, if you have a typical PV installation of around 10 panels on your roof, then this will be around a 4kW maximum supply.
This basically means that you cannot use more than 4kW at any time. Any load above 4 kW will come from the grid, no matter how big the battery is.
Management is simple maths, but can mean you need to either set schedules, or remember to turn things on and off.
Let’s say you want to run the washing machine and the tumble dryer and they both draw 3 kW each and you have a 14kWh battery. In theory, this is enough to cover the 6kWh use of the appliances, but it runs through a 4kW inverter. Therefore, instead of running the 2 appliances together (drawing 6kW for 1 hour) you will need to schedule them to run one after the other (drawing 3kW over 2 hours) to maximise the energy use in the battery.
My final advice for electro-tech? As we get more and more ‘stuff’ in our homes, and we replace fossil fuels with electrically driven technologies, we need to be sure of two main things.
First, that we have enough energy to run what we need, and second, that all the systems and appliances we have can be optimised and controlled to meet our expectations. After all, there is no point in having all the electro-tech if any of it is not going to be used.
To dive deeper into the different elements of an electro-tech home, take a look at what I've changed since first installing a heat pump in 2018, and view my thoughts on whether the changes we are making can ever result in a zero energy bills home.
