If you have started in solar then maybe the next step is putting that solar power to use in your home. Its a great way to save money over the year and can be cost effective. But there are a few ways to do this, so lets take a look at them here.
External power share.
For most, you may be at the power where the man cave /garage has a small solar installation and you have some items running on solar but you have this independent to the rest of the home. This is really common and here is what you can do.
Firstly you cannot in general connect a off grid stand alone inverter to your homes power connections, they are out of synk and things will burn. You could if you have a grid enabled inverter.
Your choice here is change the inverter or add one which is compatible and able to do this safely.
Can you use off grid solar panels for home power?
You can, you can buy a grid tied inverter and connect the solar panels to this which will then power your home.
Provided you have the right sort of panels, or you connect smaller panels in series to reach the start up voltage of the inverter. Just hook up and connect panels. The inverter should be ENA registered which means that it would be legal in the UK.
if your solar panels are “normal” that’s greater than 30v mpp, then a micro inverter may be the best option, you can use our 800w inverter with two panels. or 4 smaller panels as the inverter has a 25v start up.
Thats 2 in series for each of the MPPT. The maximum power voltage is 65v per mppt input which means that you can use a combination of panels on each of the PV connections.
If you have more panels then the growatt 1500w string inverter may work for you over the micro inverter. this has a 65v start up and you can panel up to 450v. This allows you to have a larger system to provide power to your home.
Read more into Micro Solar Here
Change up to a hybrid inverter.
Hybrid inverters come in a few flavors, but some have more features than others and some are off grid. They are generally miss labeled more often than not, which can cause serious risks. For the most part they have batteries and integrated hardware to charge from solar as well as AC grid power.
Victron Energy have a 48v/3000w grid inverter, this means that you would have to think about batteries (4x12v) or the victron 24v/3000w inverter (2x12v) There are of course costs with Victron and the long list of “and you will also need” to make the system work. The Victron units do NOT come with a solar charge controller, and will need to have a controller (CT) connected to the grid side so that you are not pushing out all your power to the grid. There is nothing stopping you using your off grid solar set up to charge the battery.
You could also use the Sunsynk hybrid inverter – the 3.6kw puts you in the self and easy install bracket. This has multi input and has a solar charge controller built in and costs less that the Victron units while being robust and globally respected hardware.
The hybrid inverters can have a EPS – off grid function, which means it keep the power on. and allows you to run critical loads. They can work in different ways, such as pass through, which would make them work like a UPS.
Can I use my off grid to power part of my home?
Yes you can, but you do have to take extra care. Bonded links, bad wiring and jumped wires are all part of the happy homes of the UK, meaning that you could think your isolated but may not. Moving part of the home is also not as simple as you would think. Most homes are wired from what is called a RING, basically a loop of wire that usually 4 of these, up and down stairs, sockets and lights. There is usually a shower and a cooker cable, which are not rings. I say this because if you wanted to put some item off grid, like the washing machine, this is part of all sockets down stairs. Therefore all things on a ring will be using the power.
Making part of the home off grid.
Wiring the home for off grid or rather part off grid takes some considerations and on our old website we had a detailed document about that. Here I will skim the information, but it should give you some idea.
Using the ATS. The ATS is connected to the output which you want to put on the load, with the inverter on one side and the grid on the other, so that the grid becomes your back up power. But you do need to think about what your doing or what the limits maybe as well as requirements.
For example if you took both your upstairs and downstairs lighting off grid, you would need to pull both of the circuit rings (four sets of wires) into a small consumer unit. The input which is fed by the inverter and grid, and the ATS in-between giving the out to the circuits.
Lights are not on that often and with new LED lights the power draw in the home is likely to be around 70watts. And so that we are looking at this in perspective that’s around 1.7kwh of power if you left all your lights on for 24 hours. This may be more of a waste than a benefit of having solar.
You could add upstairs sockets to make the principle worth doing. But here we come into more complications.
To be off grid the circuit needs to be isolated, but you also need to keep an eye on the load and peak differences. For example a laptop, computer and three phone chargers, the bathroom extractor fan and a vacuum cleaner would be around 3000w of peak load, with 2kw being from the vacuum. It does not happen often, but it will be the load that the inverter needs to provide for the peak power.
[ there will be a post on earth bonding problems to read too]
Stepping in to solar usually comes in two forms, off grid out building and the move to the home or part of it. There are some complexities due to the way our electrical systems work and the different approaches which can be problematic when wiring or part wiring your home into an inverter, I have covered this in some detail in the linked post.
Switching solar between inverters/systems
If you have off grid and want to use solar in your home, then you can switch solar between an off grid to a grid tied system. You will need to have capable 3 way switches for the DC power from the solar and then you can simply power down to reduce loads before switching between the two. it certainly would be more simple than integration and altering wiring in the house for a part off grid system.
Remember:
Messing about with power can be dangerous, simple things can be complex or hidden risks that can burn your house down or shock you to death. Understanding how to do something and doing it are two different things and there is a lot more to it that I do not cover in articles posted here. What may appear to work could be unsafe rather than show itself as a problem right away. Little steps.
Always try to go for the simple options, hashing together some mash up is often asking for trouble. You need to have the right kit that is safe and legal to use and is up for the job.
Installation
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