It’s the dream of many to live off-grid, especially with energy prices going up and set to go even further. The advent of solar batteries has made independence a lot easier – and cheaper – and so lots of households are taking the plunge.
It’s not something you can do overnight, though; moving off the grid, even partially, needs a lot of forethought and preparation. If this is something you’re planning, here’s what you need to consider.
Am I going totally off-grid, or just partially?
If you’re disconnecting fully, then you’ll need to look at larger systems. Most people stay on the grid just in case there’s a long period of bad weather or there’s a technical problem – they have the grid as a handy back-up.
You need to know how much your household uses at peak times – if you use 2kWh, but your PV system only generates 1kWh, you’ll need to buy the deficit from the grid. Alternatively, if you generate more than you use, you can sell your excess to the grid.
If you decide to leave totally, you’ll need a big enough system to power your house and to charge your storage battery. You should focus on your battery and buy the biggest you can afford.
How big does my system have to be?
To work out what your usage – and therefore your need – is you should look at your electricity bill. You’ll see the total number of kW used in the billing period (usually around 90 days). You simply divide the total number of kW by the days in the bill.
So, if you’ve used 1,800kW in 92 days, your daily usage is 1,800 / 92, which works out at 19.5kWh on average.
If you’re going totally off-grid, you need a PV system that will cover this daily need. You won’t need a 20kW system, though, as your panels will be generating power for at least seven or eight hours a day. For a 100% off-grid system, a 5-6kW system will do nicely and for a hybrid set-up, 3kW will do.
What batteries do I need?
For lots of storage you need deep cycle batteries as they can discharge quite a long way and still last for several years. If you’re totally off-grid, though, you’ll need more resilient ones – tubular gel types, maybe.
Have I enough space for a standalone system?
Most people have their panels on the roof, but there’ll always be trees or shade from other buildings getting in the way at some point. If you have a patch of land where you can place an array with total exposure, then this might be a better option.
Can I still have my aircon?
Yes; we all need our aircon! However, you’ll need to spend a bit more on your PV system and your aircon. If your aircon system is new and efficient, it won’t use so much power; cheaper systems tend to use more electricity, which is wasteful.
3kWh to 5kWh is enough for a smaller aircon and medium to large systems will need anything from 6kWh to 10kWh.