# Forum Home Renovation Solar Electrical Systems  Solar panels plus batteries

## barney118

As you might be aware they are now trying to flog off PV systems with batteries, I went down this path only to find out that you have to nominate 1 circuit the batteries will supply on what's the point of this? Surely you can run more than one power circuit on batteries? Also if you want the batteries  and PV system you have to pay for the whole system up front. Whereas if you just get the PV system you can pay by the mth.  
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## OBBob

I think it should be taken as a developmental step ... I'm certain it'll head this way but needs more maturing. The interesting thing though was the story yesterday about the amount of investment required in the electricity networks over the coming years regardless of whether off-grid takes off or not.

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## phild01

Saw something yesterday about Tesla now pushing this home solar storage to dramatically bring down battery costs.

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## Spottiswoode

I spoke to my brother in the game. He said batteries aren't the best thing...yet. The reason you choose one circuit is so you can focus your usage. Sure they can provide a full circuit connection, but it runs the batteries down too quick, or you need heaps of batteries. I've just paid a deposit on a system, battery ready as the cost of putting the batteries in now is a bit high for the gain I would get. 
I have ordered a 4kw system with panels split between the north and western roof sections so that we generate power in the morning, and also the afternoon when we are more likely to use it.

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## toooldforthis

it has been a while since I looked into it but last time around the tesla marketing was misleading - the batteries were not viable for continual (ie overnight) discharge and recharge, just for the occasional power outage. they (somebody, not necessarily tesla) will get there eventually.

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## barney118

> I spoke to my brother in the game. He said batteries aren't the best thing...yet. The reason you choose one circuit is so you can focus your usage. Sure they can provide a full circuit connection, but it runs the batteries down too quick, or you need heaps of batteries. I've just paid a deposit on a system, battery ready as the cost of putting the batteries in now is a bit high for the gain I would get. 
> I have ordered a 4kw system with panels split between the north and western roof sections so that we generate power in the morning, and also the afternoon when we are more likely to use it.

  Not good how you can only supply one circuit from batteries as design of houses don't work like that. How did you go with the Nth/west option? How many panels split? I notice they have been trying to convince me to go with just west option as that's where most of my room is east and west. How do you work out what's best I know they charge more for a split but does the benefit outweigh this.  
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## Spottiswoode

> Not good how you can only supply one circuit from batteries as design of houses don't work like that. How did you go with the Nth/west option? How many panels split? I notice they have been trying to convince me to go with just west option as that's where most of my room is east and west. How do you work out what's best I know they charge more for a split but does the benefit outweigh this.  
> Sent from my iPhone using Tapatalk

  You can split the circuit in any way you like for the battery output, it's just that you either need a whole lot of batteries to power everything, or you drain them too quickly. My brother suggested that one circuit would be a better option, targeting your usage which helps the battery system cope with a more even load. It's a bit of a tradeoff, one that I'm not jumping into yet. I did consider getting a battery for the lighting and fridge circuits, but if we have a blackout i've got torches and a camp fridge. 
We've managed to roughly split the panels 50/50 across the two sections. My reasoning was that I'd be able to get solar input in the mornings for stuff like washing machine and pool pump at the start of the day. The inverter we have been specified has two inputs, so the different arrays can operate independantly with the different sun angle. Our roof is quite steep at 45degrees, which means the panels will be slightly less efficient and the western end wont get sun as early and the northern side will lose it earlier in the afternoon as it would with a more standard 22degree roof. The roof also wouldn't fit much more than 3kW on the western end, another reason to split the system. I was shown a spreadsheet of the potential output comparing the different setups and chose according to my needs. 
The reason they promote the west option is that the panels will get more sun in the afternoon, which is when you want to generate power to use, and offset the peak hour tariff from the grid. It's kinda silly, but angling the panels for less sun efficiency is actually more cost effective, remembering that panel power output is proportional to the sun angle.

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## Black Cat

Ok, so how many batteries would you need to be stand-alone (one person, low consumption rate, winter heating by wood stove, but need for summer cooling from time to time)? And how would you orient the roof if it were a new build in Tassie?

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## toooldforthis

ABC Catalyst and 730 Report had items on this recently (like last week I think). 
The way they were talking the batteries/circuits were fine. It was more to do if they cost effective or not.

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## woodbe

Here's the link to the Catalyst show: Catalyst: Battery powered homes - ABC TV Science

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## Black Cat

Thanks Woodbe, I actually watched it the other night (used up my month's download allowance on that and a show on Better Homes and Gardens about shipping container makeovers, lol). Some batteries seem to be retailing around the $6000 mark now - so two of those might be useful I thought. But having failed Physics 101 I find it really hard to understand how many panels would be needed to keep it powered up, particularly in winter when the  lights are on early. I am thinking lower draw lights might be the answer.

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## phild01

I saw that episode on Catalyst but wasn't convinced that the technology was anywhere near ready yet (especially off grid).  I think it would work ok but once you factor in the air con, washing machine and fridge, it might get  a bit tricky.  Lighting is the least of your worries.

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## Black Cat

who has aircon? lol. Pedestal fans r us. My consumption is very low. I am currently paying around 85 a fortnight and am $600 in credit. But I would rather err on the high side in calculating things, as I will probably also have a telly (no aerial here).

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## phild01

LED lighting and LED LCD TV's are great power savers now.  The fridge and washing machine needs careful calculation, if off-grid, as well as how many sunny days you get in a year.  And a plan for hot water backup.

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## Spottiswoode

Wot e said. Lights are the least of your worry when working it all out. Typical modern efficient lighting (usually led) is less than 10w per light. Motor stuff is where the usage is at. Fridge is probably 200w but doesn't run all day, washing machine is probably 1500w. Have a look around for power consumption figures.  
I I had a quick look here: http://www.essentialenergy.com.au/as...ce_Nov2011.PDF which was interesting.

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## Black Cat

oooo very useful! Thanks Spottiswoode, and it even helps on deciding what fittings to use (instant hot water rather than stored etc). Very useful indeed.

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## toooldforthis

Explained: The Tesla Powerwall and what it means for Australia's energy market - ABC News (Australian Broadcasting Corporation)   

> *How much does it cost?* 
> If you already have solar panels, the Powerwall and a compatible inverter will cost you between $12,000 and $12,500 depending on which inverter you choose.
> Energy companies are selling Powerwall packages for between $13,990 and $16,500 (GST inclusive) and with consideration to rebates for small-scale technology certificates (STCs).

   

> Andrew's household roughly uses around 38.4kWh of energy per day at a price of 21.81 cents per kWh. Andrew and his wife both work from home part-time, which makes their energy use higher than most households. It also gives them more potential to tap into their own solar energy rather than feeding it to the grid.If Andrew was to install a 4kWh solar array on his roof, he could expect to generate around 15.6 kWh of electricity per day, on average. About 7.5 kWh of this would be required to charge the Powerwall due to inefficiencies with the battery and inverter, which could then be used to offset 6.4 kWh of his energy use during the night when his solar panels are not producing electricity. This would save him $1.40 per day (6.4 kWh x 21.81c).If we assume Andrew did not use the remaining 8.1 kWh of solar energy after charging the Powerwall and fed it back into the grid, this would earn him $0.49 per day with a feed-in tariff of 6 cents per kWh. Together with the savings from using the Powerwall to store electricity for later use, this will give a total saving of $1.88 per day, or around $687 per year. With Origin's total system cost of $16,500, Andrew has a *payback time of just over 24 years, or 2.4 times the warranty period.*But since Andrew and his wife work from home part-time, this allows them to make the most of their solar panels. If we assume Andrew could use half of his solar electricity remaining after charging his Powerwall every day, then he would lose $0.24 per day in feed-in tariffs but would save an additional $0.88 per day in electricity costs (4.05kWh x 21.81c). This would save him $2.52 per day or close to $921 per year. *This equals a payback time of 18 years.*

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## Black Cat

Finally tracked down my last power bill - 1400KWh in period 7 Oct to 8 January. Does that help at all?

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## Spottiswoode

> Explained: The Tesla Powerwall and what it means for Australia's energy market - ABC News (Australian Broadcasting Corporation)

  So this shows that battery systems are not viable for the average person that is grid connected... yet. However, if you are going to need to connect a new property to the grid, and that property is a fair distance from the grid then it changes the equation. If you are going to spend $10k on connecting to the grid it substantially changes the sums for installing an off grid solar/battery system.

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## woodbe

Black Cat, So around 15.5kWh per day on average during spring/summer. That's a lot for a one person household. If you want to go off-grid, the first thing I'd be doing would be to improve efficiency of the home. Super Insulate, double glaze, fix air leaks, improve appliance efficiency, change globes for LEDs, Shade windows from summer sun, etc. What sort of hot water system have you got? 
Panels on the roof face north for best overall efficiency, roughly at a tilt corresponding to your latitude, around 40 degrees for tassie.

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## Black Cat

Oh  :Weeping: . I suspect the coffee machine may be a contributor .... Clearly I will need to do some sums and work out where I am losing power then. And the freezer. Hot water is presently solar with electrical boost which I forgot to turn off this summer. The list goes on.

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## Spottiswoode

> Oh . I suspect the coffee machine may be a contributor .... Clearly I will need to do some sums and work out where I am losing power then. And the freezer. Hot water is presently solar with electrical boost which I forgot to turn off this summer. The list goes on.

  Yup, 15.5kwh sounds too high. Our famly of five used around 17.5 before we got the bigger house and pool. We didn't use much AC and had low wattage listing, but were otherwise not very power thrifty. No switching standby items off at the wall, PC left running a lot and on standby near all the time, ceiling fans run often. 
Hot water is a big one. My parents lived in a house wired by my grandfather, a licences sparky. Their little off peak hot water unit upstairs (1of 2) was often switched from off peak to the normal circuit when visitors were staying. The switch was illegal due to the off peak requirements. Once when it was turned on and forgotten about the electricity company came to investigate why we had such a big power bill. 
hot water boosters need to be on a timer switch or something. ie one press gives you 12hrs of boost and then it cuts off so you can't leave it on.

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## Black Cat

Actually, now I look at the bar graph they supply I seem to have shot up from the 'well below normal household usage' to very high household usage. How odd. This happened once before (while I was away from home during the week and the hot water booster was turned off), very mysterious. Short of the neighbour running a power cord to my external power point (which would be a tricky thing to manage given my erratic pattern of absences), I don't know what is happening. I think it is time to officially panic. Thanks Spottiswoode.

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## phild01

Might be good to install a remote power usage meter to the meter box.
Maybe like this one: http://www.ebay.com.au/itm/efergy-HM...UAAOSwRLZT4McZ

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## Black Cat

What does that do Phil? (oh, I Just read the seller blurb - good tool to have!) By the way I have just priced a standard connection (including three poles and underground to the house site) and it comes out at a bit over $1500, so I think that may be the end of my exploration of modern technology for a while. Bum.

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## phild01

> What does that do Phil? (oh, I Just read the seller blurb - good tool to have!) By the way I have just priced a standard connection (including three poles and underground to the house site) and it comes out at a bit over $1500, so I think that may be the end of my exploration of modern technology for a while. Bum.

  Yes, if power seems to be going missing that meter would help you understand, as it accounts for all power you are paying for. 
$1500 also seems to be a better value outcome at this stage for you.  I wouldn't be investing in solar or batteries until the technologies improve substantially.  Not sure why hydrogen isn't part of the solar solution either, but the day when we can economically live off grid will be much welcomed. Bumping up the price of our street supply shouldn't be the means to achieve it either.

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## Spottiswoode

$1500 for grid connect? Sounds pretty cheap, wonder is that subsidised by govt? Anyhow, you can still dream and design etc.

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## Black Cat

Indeed I can Spottiswoode. Not for connection, just for the poles and underground to the build site. Connection is a separate fee. I would probably be looking closer to 2500 all up, but still. I could get some panels and get the paltry feed-in tariff that Aurora offers, but design the system to maximise panel use while I can. I think I have worked out where the power is going btw - I have been using the oven a lot lately ... Too many pizzas methinks.

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## barney118

My update I have signed up for 4.68 kW system no batteries I'll wait and see how this goes and battery prices to come down. Looking at my history I can see when I started thinking about them I was up for $9k now it's $7k 2.5 yrs gone past.  
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## Spottiswoode

Unfortunatley our supplier needed a subcontractor to install, which they wouldn't do for the right price due to our steep roof. Deposit refunded, back two steps. Still looking for the same system and now have two quotes. One for $10k (ish) and one for $7.3k(ish) the higher quote came from the company that gave me the right impressions, tradie visited and inspected the house. The second cheaper quote was supplied by two salespeople by looking at their book of prices, without looking at the house too much. If the price was comparable I'd jump at the first quote, but $3k is enough difference to have to rethink things.

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