Can you go off-grid with solar and energy storage?

by James Martin II on July 20, 2016

in Batteries & Energy Storage,Off-grid solar power, Stand-alone solar power, Remote solar power

These days, almost everyone considering solar and battery storage is wondering if it’s possible to disconnect from the grid altogether; ‘going off-grid’ seems to be all the rage. Just how feasible is it for the average household to go off grid – and is it really worth it?

How easy is it to go off-grid with solar-plus-storage?

The short answer to this question is that unless your electricity usage is minimal (around 5-15 kilowatt-hours per day), it’s not very easy to disconnect from the grid and still have all the comforts (and/or necessities) you’re accustomed to. Even with the cost of solar and energy storage falling, installing batteries really still only makes financial sense in a handful of situations.

If you’re in a major urban centre, deciding whether or not to truly get off the grid should be something you consider very carefully. To do so, you’ll either have to a) significantly change the way that you use electricity (becoming hyper-efficient), or b) spend a significant amount of money on a solar-plus-storage system large enough to get you through a cold, dark winter.

A note about battery storage capacity

Depending on which battery type you’re looking at, the actual usable capacity (usually given in kilowatt-hours, kWh) may be different from the nominal capacity. This is because ‘depth of discharge‘ limitations – not all batteries can be fully discharged without damaging them permanently. In the article below, we are only talking about usable capacity – if you’re shopping around for a battery storage system, make sure you know the difference.

What would it take to go off-grid?

The discussion below is purely about simple numbers – how many kilowatts of solar and how many kilowatt-hours of battery storage capacity would you need at a bare, bare minimum to get off the grid? It doesn’t touch on some of the ‘quality of life’ and other considerations that come along with disconnecting to the grid. We recommend that you check out this 10-point ‘Reality Checklist’ of considerations for those contemplating going off the grid.

But for argument’s sake, let’s say you want to take the plunge and cut all ties with your local network infrastructure. How much solar-plus-storage would you need?

Let’s imagine a home in Sydney and a home in Brisbane. Both have unobstructed, north-facing roofs with plenty of room to put solar panels. On weekdays, both homes use a lot of electricity during the morning and evenings (as per the graph below). What’s the minimum amount of solar and battery capacity these homes would need for basic energy self-sufficiency?

While reading the result below, keep in mind you’d actually want about 3x as much solar & battery storage capacity (or a back-up diesel generator) to ensure you can get through patches of rough weather.

Also remember that all results are indicative. Make sure to consult a qualified solar designer/installer ensure that you get a system that is appropriately sized for your home.

Electricity usage high morning afternoon

Read more about electricity usage patterns.

Some example scenarios

Sydney: Typical electricity usage scenario

Let’s say your Sydney home uses 20kWh of electricity per day on average throughout the year. At the height of summer, you use 25kWh (because you have AC) and on a typical winter’s day you use 15kWh (you have non-electric heating).

What size system would you probably need? 7kW of solar and about 12kWh of usable battery storage would be the absolute minimum you’d need for daily self-sufficiency (on average).

Sydney basic self-sufficiency snapshot

 

Sydney basic self-sufficiency 7kW solar 12kWh batteries

A snapshot of what basic energy self-sufficiency would look like in Sydney – 7kW of solar and 12kWh of usable battery storage.

Sydney: Low-usage scenario

Let’s say your Sydney home is highly efficient, using only 10kWh of electricity per day on average throughout the year. At the height of summer, you use 15kWh and on a typical winter’s day you use 7kWh (you have non-electric heating).

What size system would you probably need? 4kW of solar and about 7kWh of usable battery storage would be the absolute minimum you’d need for daily self-sufficiency (on average).

Sydney low usage basic self-sufficiency outputs Sydney low usage basic self-sufficiency charts

A snapshot of what basic energy self-sufficiency would look like for an energy-efficient home in Sydney – 4kW of solar and 7kWh of battery storage.

Brisbane: Typical electricity usage scenario

Let’s say your Brisbane home uses 20kWh of electricity per day on average throughout the year. At the height of summer, you use 25kWh (because you have AC) and on a typical winter’s day you use 15kWh (you have non-electric heating).

What size system would you probably need? 6kW of solar and about 11kWh of usable battery storage would be the absolute minimum you’d need for daily self-sufficiency (on average)

Brisbane basic self-suffiency outputs Brisbane basic self-consumption charts

A snapshot of what basic energy self-sufficiency would look like in Brisbane – 6kW of solar and 12kWh of battery storage.

Brisbane: Low-usage scenario

Let’s say your Brisbane home is highly efficient, using only 10kWh of electricity per day on average throughout the year. At the height of summer, you use 15kWh and on a typical winter’s day you use 7kWh (you have non-electric heating).

What size system would you probably need? 3.5kW of solar and about 7kWh of usable battery storage would be the absolute minimum you’d need for daily self-sufficiency (on average).

Brisbane low usage basic self-sufficiency outputs Brisbane low usage basic self-sufficiency charts

A snapshot of what basic energy self-sufficiency would look like in Brisbane – 3.5kW of solar and 7kWh of battery storage.

Off-grid living in the city: Dream or reality?

The information above aims to give you an idea of the minimum that would be required for a home to be energy self-sufficient with solar and batteries. As noted above, the reality is that you’d need significantly more capacity to go truly ‘off-grid’ (it’s probably safe to multiply the results in each scenario by 3 to get a better idea) – usually not economically or physically feasible, especially for urban homes with limited roof space for solar panels.

Our aim in publishing this information isn’t to discourage anyone from considering solar-plus-storage for their home, but rather to provide a ‘reality check’ with regard to the feasibility of literally cutting ties with the grid where doing so is not a necessity.

What is apparent from the graphs above is that high degrees of energy self-sufficiency will be possible with solar-plus-storage systems. In particular, it is is not unthinkable for a household to meet its afternoon electricity demand using solar-plus storage – and reduce their energy bills in the process – in Sydney or Brisbane.

Explore the possibility of solar-plus-storage for your home with Solar Choice’s Solar & Battery Storage System Sizing & Payback Estimator tool

Want updates about energy storage? Fill out the form below.

On the back of the success of our informative and impartial Solar Quote Comparisons, Solar Choice is currently in the process of developing an online comparison platform for energy storage solutions – for retrofit and brand new installations. If you’d like to be informed when this new service goes live, please enter your details into the form below and we will be in touch.

© 2016 Solar Choice Pty Ltd

James Martin II

James Martin II

James has been working as analyst and online development manager for Solar Choice since 2011. He holds a master's degree in Environmental Management from UNSW, and a bachelor's degree in Philosophy from Bridgewater State University in his native Massachusetts.
James Martin II

{ 15 comments… read them below or add one }

sam September 20, 2016 at 9:12 pm

Hi,

I am looking for an off grid system and would like to connect it to a gas backup generator.
My daily consumption is about 15KW per day. Do you think I can go off grid with a 6.24kw solar and a Tesla PowerWall and connect the system to the generator for backup? Would one Powerwall battery be enough or do I need two of them or more?

Thanks,

Reply

Solar Choice Staff September 29, 2016 at 12:13 pm

Hi Sam,

Your consumption is relatively low, but going off grid requires a lot of backup capacity. If you’re doing it for financial reasons, you’ll probably end up paying more in the long run with batteries & a generator. If you’re doing it for environmental reasons, you might want to ditch the generator and go with more solar & battery capacity.

We have an Off-grid Solar & Battery Storage System Sizing Estimator Tool that you can play around with, but keep in mind that it has limitations and is only good for ballpark figures. If you want further details, you’d need to get in touch with some installers (we might be able to help).

Is there any reason you’re thinking about installing a Tesla Powerwall? There are a number of other products out there, some of which are a bit more flexible and/or better suited for an off-grid solar system. Check out our Battery Storage Product Performance Comparison Tool to learn about more.

Reply

mark Roskell September 14, 2016 at 11:34 pm

My daily usage is 30kWh.I currently have a 2Kw system installed,would it be a wise investment to upgrade my system after the feed in tariffs cease at the end of this year.What system output would you recommend i upgrade too?Regards Mark

Reply

Solar Choice Staff September 19, 2016 at 9:01 am

Hi Mark,

Whether or not you should expand your system depends on a number of factors. (First off – I’m assuming you’re not actually interested in going off grid even though you’ve commented on an article about going off-grid?)

If you’re in NSW, the two first things I’d recommend doing are 1) install some kind of a monitoring system (preferably for solar and your household energy usage), and 2) look around for someone to replace your meter at the end of the year.

The monitoring will allow you to establish what your baseline consumption is and how much of your solar you’re actually likely to be ‘self-consuming‘ (i.e. how much solar energy is produced while you’re running devices in your home?)

The meter change will be necessary to ensure that the solar energy your system produces goes into your home before it goes into the grid. Most solar homes on the Solar Bonus Scheme are on ‘gross’ meters, which means that all of your solar energy goes directly into the grid. After the SBS finishes, that solar energy will be worth much less (about 6-8c/kWh, depending on your retailer), which is why we recommend switching to a ‘net’ meter. A net meter will allow the solar to go first into your home (running your devices and reducing the amount of energy you have to purchase from your retailer in the first place).

You can read more about your options in the run-up to the end of the Solar Bonus Scheme in this article.

As far as expanding your system is concerned, it is possible that it would be worthwhile, especially as solar installation costs have come down significantly since you had your original system installed. Although installing some kind of monitoring would be the first recommendation because it would be more accurate, you’re also welcome to check out our Grid-connected Solar System Sizing Estimator Tool, our Solar & Storage System Sizing Estimator Tool or just go ahead and check out our whole suite of tools here.

Best of luck with your system!

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Dipu Suresh July 30, 2016 at 10:51 am

I have 4.6kw panels installed and my total consumption per day is less than 4 kw per day(50% from solar) and less than 2 kw @ night.I am just wondering if i can install an enphase or tesla battery to my present invertor and go off grid. As my 80% of usage bill is supply charge ie around 1.50 $ per day.
Is there any other alternative,which is cost effective?

Reply

Solar Choice Staff August 1, 2016 at 10:56 am

Hi Dipu,

With such low energy consumption, you’re in a great situation for considering going off-grid. Do you already have solar?

Tesla’s Powerwall is one potential option for you, but as of now the Enphase AC Battery is only for grid-connected systems. You could consider Redflow’s ZCell or Aquion’s ‘saltwater’ batteries. All of these have 7-10 year warranties.

You also may want to seriously consider getting some lead batteries – while not particularly ‘cool’, lead-type batteries have been around for decades and are the stand-by solution for off-grid solar systems.

If you’d like to compare battery prices, feel free to fill out the Quote Comparison Request form to the right of this page. If you already have a solar system just tick ‘battery storage only’ at the top of the form.

You can also give us a call on 1300 78 72 73 if you have any questions.

Best of luck with your system!

Reply

sue March 10, 2016 at 12:27 pm

If we go off the grid….and we sever all ties with electricity company…do we still have to pay for “Supply Charges” because it is deemed we CAN get electricity and it goes past our property…we are in tamborine qld..acreage.

Reply

Solar Choice Staff March 10, 2016 at 12:43 pm

Hi Sue,

If you actually disconnect from the grid (i.e. no service from the network, even as a backup), then you shouldn’t have to pay supply charges as long as you’ve mentioned this to your supplier. If you’re still physically connected to the grid, however, you’ll still continue to be billed these fixed charges even if you don’t purchase any electricity from the grid (i.e. you’re completely self-reliant with regard to electricity).

We recommend you check in with your electricity retailer to confirm one way or another.

Reply

sue March 10, 2016 at 2:33 pm

Thank you, that makes sense…..but yes I’ll check, as friends who are on tank water still get charges as the water supply goes past their property even though they are not connected and they were on tank water way before supply went thru…so you just never can tell what these major players try you for….its all getting out of hand with charges for living…they’ll bill us for oxygen next….sorry, off track. Many thanks. Sue

Reply

Phil September 29, 2015 at 8:30 am

I have an off grid 120sqm home in an Alpine area north of Sydney with 4.5kw solar panels , 1000 ah 12v (6 x 2v) traction wet cell batteries used for 5kwh storage needed per day out of solar hours.The average home consumption is 10kwh per day via a 3/9kw inverter with LPG cooking / hot water and wood for cooking and heating in the cold months. Appliance use is heavy as have the mod cons of a city home , but the appliances are newer ones – not high end but mid range (ie samsung direct drive front load washer , beko fridge ) so find they use little energy. This system using half priced scratch and dent sale solar panels and DIY install ( legal for the solar part as under 120v dc) cost less than $8k and has proven 99.9999 % uptime due dual redundancy design and a 3.4kw inverter auto start petrol genset that runs for 30 hours per annum as triple redundancy and “mushroom growing weather” battery top up. It is also built to the australian standards and has 80ka lightning and surge protection many systems dont have as well as high end industrial Hydraulic magnetic dc circuit breakers sourced as new surplus stock on ebay overseas. Surplus power feeds 2 x 450 watt wall panel heaters and the system has been running flawlessly for 2 years with an ongoing replacement and capital costs of $1 a day for the interest on the capital and $1 a day for the battery and hardware replacement budget and 20 cents a day for the genset fuel and consumables for the annual service. Apart from battery top ups and cleaning the panels and fans in the equipment no other input is required. With the Aussie dollar dropping i belive it would cost $10k in todays money for this system

Reply

Solar Choice Staff September 30, 2015 at 9:58 am

Hi Phil. It’s great that you managed to get this system up and running yourself – pretty impressive. While we can’t recommend that anyone without proper training should try this at home, we’re also sure that the most intrepid of our readers will do so anyhow. We wish them the best of luck.

Reply

Phil October 2, 2015 at 4:11 pm

It’s actually legal under current australian legislation to diy your own solar if the maxium dc voltage is less than 120 v dc as it’s classed as ELV . If you arrange your open circuit solar panel strings to be less than this (typically no more than 3 in series) and then parallel them then it’s legal.The 240v inverter to house and the house of course have to be installed by an electician.Many out there who have had electronics as a hobby could easily do what i have done safely as we understand DC voltages , insulation , shorts , protection , grounding and high currents well.

Reply

Solar Choice Staff October 12, 2015 at 2:01 am

Thanks for the insights, Phil!

Reply

Madhab saha August 22, 2015 at 8:39 pm

Should I have a 5 kW unit in Clarence town nsw ? What would be the average feed in tariff ? If I installed batteries for storage , would I be able to run 50 % of my needs? Just two adults in the family. In winter we will,have wood fired slow combustion heaters. Any suggestions and advice ?

Thanks and cheers

Reply

Solar Choice Staff August 25, 2015 at 5:16 pm

Hi Madhab,

Meeting 50% of your electricity needs with solar plus storage is reasonable enough – especially if you have low usage. What’s your daily average kilowatt-hour (kWh) usage at the moment? How about in December and July, when the solar radiation levels are at their highest and lowest, respectively?

As for the feed-in tariff, you’re probably not eligible for much (no one is these days). That means that you’ll want to try to self-consume all of the energy that your panels produce. Without batteries, this means using as much electricity during daylight hours as possible. With batteries, however, you can ‘shift’ some of the solar produced during the day to the evening hours.

I should also advise that you be careful – 5kW may actually be too large for your needs. You don’t want to spend more than you have to!

Reply

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