Off Grid Living – In Luxury
So, we are now entirely off grid in terms of energy supply. Whilst we are connected to mains water, our electricity is reliant on solar panels (we have a commercial grade generator for backup obviously!) and our gas supply is butane bottles.
The system is a 48v 17.2kWH and should provide 2kWH of solar energy per sunlight hour. For 2 adults, working from home, we figured that was a workable amount of electricity.
Of course, prior to switching to off grid, we did receive a couple of warnings.
- You shouldn’t run very high load appliances like the washing machine unless you do it in the middle of the day when lots of power is coming into the batteries and you should really only use the economy wash setting. Not a problem as there are generally only 2 adults in the house and we mostly use the economy wash no matter where we are living.
- You won’t be able to use a hairdryer. Well, my hair is short and Joanna doesn’t bother drying her hair unless we are going for a night out. Considering the remote location of the house, going out on a regular basis like we used to isn’t really an option so, again, no problem.
- You can only use the very high load appliances at night such as the hoover if you turn the generator on because it draws so much power. We only turn the generator on at night if we’re running a high load, and, just so you don’t get the impression we live in a dust pile, the floors are all wooden so they’re swept.
- Irons are high load appliances as well, enough said! Who wants to stand around all day pressing things flat when there is so much else you could be doing. (We had a huge steam producing behemoth that consumed over 3.5Kwh so now we have a modest 700watt travel iron for those times when you just can’t be creased!)
All in all, these were restrictions we thought we could live with.
And that’s when we discovered that not all solar setups are created equal. I wasn’t very knowledgeable about solar energy until a few weeks ago but have rapidly had to increase my knowledge in order to get the system to give us the amount of energy of which it is capable.
The Solar Panels
Firstly, the solar panels themselves. We have 10 x 200 watt 24 volt panels at the moment, all well positioned (facing south) and get the most sun hours possible.
This gives us in an ideal scenario 2kW/hr charge into the battery bank. We’re only using 8.6kWH maximum so that’s 4.3 sun hours required to fully charge the batteries. Obviously, you need to minus the running load during the day as the solar array will power the devices running as well as charging the batteries (providing you don’t use more power than the array is generating of course! This is where the no hair dryer & irons bit comes in). On average we’re getting over 6 good sun hours a day all year round, summer obviously peaks and winter troughs.
We have a Victron Energy MultiPlus Inverter / Charger the biggest and best model they do which is rated at 5000VA. Up to 6 units can be run in parallel so if in future we need more power we can simply add another 1 or even 2 units in if needed. The system is one of the best on the market and switches power sources in less than 20 milliseconds. It has 2 AC power outputs so that you can put essential equipment on the primary and non-essential on the secondary. It has three phase capability and handles generator input seamlessly.
The batteries are large 2 volt lead acid 360 amp hour units, yes that’s right I said 2 volts! There are 24 of them wired in series to make one huge 48 volt battery. 360 Amp hours at 48 volts equates to 17.2kWH of energy storage. Given that you’re not supposed to discharge the batteries (lead acid – deep discharge, see below) below 50 percent of their capacity that gives us 8.6kWH which is available for non sun hours (nighttime) the system supplies the appliances during the day and charges the batteries you see.
Why 48 volts? Why not 12 volts or 24 volts?
Ok…so this is a big deal for a number of reasons. I’ll keep it as short as possible as there is a huge scope to go into too much detail here.
Basically when it comes to electricity the lower the voltage the higher the amperage which means increased resistance. This means that you need hugely thick wires (that have less resistance) to transmit a very low voltage with high current over any distance, the longer the distance the thicker the wire you’re going to need to avoid any energy loss. This is where increasing the voltage comes into play. You’ll probably be aware that most household appliances run at 230-240 volts, this is so the wires don’t have to be really thick in order for these devices to work! The same applies to the wiring in your house. Higher voltage means less resistance and less loss over distance, this is why overhead power lines run at hugely high voltages and can run on very thin wires, compare those wires to say the ones on your car battery! You get the idea.
So in a nutshell… 48 volts from the panels (wiring them in series to create that voltage) means that you lose less energy along the way and can use much thinner cables which cost much less.
We are actually having our panels re-wired so that we have 120 volts coming in from the solar array, this of course meant that we had to buy a new solar charger controller that can handle that kind of voltage and charge the batteries (48v) accordingly, but will result in more power coming into the batteries.
The Plan Going Forward
The system is fully expandable and if need be extra battery capacity can be added as can another inverter unit which will allow higher loads to be run using the battery power alone.
The Product Links
For the power hungry home or those who want to be able to have a good few days of total backup in any scenario this is a very good option.
BUY 12 x 2v OpZs Deep Discharge batteries (for 48v system you will need 2 of these, so 24 batteries in total, this will give you 84.6kW so 42.3kW useable!)
For low power consumption (fridge freezer, LED lights, TV etc). This cheaper solution will give you the power you need.
BUY Trojan 105 6v 225Ah battery (for 48v system you will need 8 of these it will give you 10.8kW so 5.4kW useable!)