Solar Panels

[Flying mermaid]

The quoted figure assumes a north facing panel at the correct tilt angle. As you are E and W the max performance will be less which is much less important that being able to use the generated electricity.

Just received a quote for 15kw roof mounted all facing one way - so 1 three phase inverter
circa $19000 (net). But all facing NE

ill probably go 10kW as I wont be able to use all of the generation and ill just get net feed in tariff for the rest.

yes we always knew we wouldn’t get the maximum with the east west split, in fact we deliberately put half each way to maximise the length of time we were generating. We also went for top end panels to ensure we generated as much as possible and degradation was slower.

For 6 months of the year we will use every scrap of what we generate - as soon as we turn the floors on. We still have another roof (also east-west), where we can put more panels, but we thought we would see how this went first and what our savings were. Also given our age and intention to sell the house in another 8 to 10 years whether it would be worthwhile doing it,

We are paying around 15.5c and our feed in tariff is 12c, so we are expecting our bill next week to be very small .

 

[Quickstatus]

We are paying around 15.5c and our feed in tariff is 12c, so we are expecting our bill next week to be very small .

What!!!! 15.5c/kWh cost of electricity???

 

[Flying mermaid]

What!!!! 15.5c/kWh cost of electricity???

yes that’s right - I think it is technically around 23.5 but then we got a massive discount for the first year. We had been very bad about getting deals but as part of installing solar we talked to friends about what they were paying and then shopped around. We were going to swap providers but our current guys came back and offered an extra special deal. We do have electricity and gas with them.

Not sure what we will do at the end of the year - some hard bargaining I guess.

What do you pay?

 

[Quickstatus]

What do you pay?

Here: Solar Panels
About 30c/kWh averaged
Then 17% discount if paid on time

So about 25c/kWh averaged discounted
But with some load shifting to off peak

 

[Irishbazz]

24.06 C/kWh here in Perth for anytime consumption, just got my second bill since installing solar in December 6.5kw east / west facing panel array. First bill was $59 and this one $83. With a 7.15 C/kWh export credit. Historically these bill periods would have been in the $400-500 range, so a very happy camper with the systems performance so far.

 

[Flying mermaid]

Here: Solar Panels
About 30c/kWh averaged
Then 17% discount if paid on time

So about 25c/kWh averaged discounted
But with some load shifting to off peak

oh yes I should have read that . That’s expensive. I think ACT is just a flat rate - doesn’t matter time of day. Although you can choose off peak if you want to, never bothered to look at that.

 

[equus]

Sydney peak solar hours is 6.3hr in Jan and 3.8 in Jul meaning a north facing 250w panel at the correct angle in Sydney in Jan would generate 250x6.3 = 1575w per day

Highly unlikely to get anywhere near that amount. 250w is the nominal panel output in ideal conditions at 25 degree. Temperature (especially in Sydney in January) will be way above that. With a typical temperature coefficient of around 0.5% per degree, and a panel temperature likely to be around 65 degrees at least, there is 20% of the output gone already.

Then factor in losses in the inverter (they are not perfect, around 96% is good) and wiring, and you will be lucky to see 75% of the quoted output for any period of time.

This is why it is highly recommended to install more "supposed" panel capacity than the rating of the inverter (and why the 33% over capacity figure is normally used).

 

[cove]

Yes equus that is the only way to get the “quoted output”. All sorts of theories aside watch the readings and don’t be afraid to put on additional panels. Do watch your electricity bills as there isn’t much point going below a zero bill.

 

[Quickstatus]

Interesting
My quote for a 15kW array comes with a 15kW three phase inverter. As the orientation is NE there seems no point to have a 15kW inverter.

Do inverters perform best at full capacity or at some sweet spot below that?.
Or should I for example get a 10kw inverter

 

[cove]

If you want 15kW just be prepared to put on some extra panels.

 

[Quickstatus]

If you want 15kW just be prepared to put on some extra panels.

The problem is that best production in January will realistically be over 8 hours and in winter might only be 4 hours for my NE roof, but my consumption would be over 24 hours. So 16 or more of those hours I will only reduce the electricity hourly price by the net feed in tariff.

Beer coaster calculations for a net 15kW array:

Summer @ 90kW/day @91 days = 8190kW
Winter @ 45kW/day @91days = 4095kW
Spring and autums @ 67kW/day@ 183 days = 12261kW

Total generation less 10% for cloudy days = 22000 kW

$20000 at 5% interest for 10 years paid quarterly (to match with electric billing) = $638.
Annual = $2552
Cost of electricity generation by solar array = 11.5c/kwh. (2552/22000)
Net feed in tariff in my area = 12.5c/kWh
Effectively the net feed in tariff is normalised cost of electricity generation by solar.

So costing me 11.5c to pump excess electricity into grid and energy retailer pays me 12.5c (but only if electricity usage is greater than feed in)
Go big and the benefit is 1c/kWh.

So putting more panels to improve the cost efficiency of inverter may not be so cost effective. Maybe better to go with smaller inverter.

At best solar on a NE roof for me would ensure 100% cover of the 8am-2pm electricity consumption and maybe an hour or two into the peak 2pm-8pm in January. The rest of the electricity would be a feed into the grid to offset any use for the 1400-0800 hrs period by 12.5c/kWh

Alternatively why not just have enough to cover consumption and not have any feed in to the Grid

Problem is a lot of solar calculations do not include the amortised sunk capital cost of the Array nor the opportunity cost of the capital and only look at the savings at the other end.
Solar panels are a depreciating asset so the capital cost cannot be retrieved.

However the cost of solar generation will remain fixed at 11.5c/kWh while electricity prices are only set to rise in spite of what Fraudenberg wants us to believe with his NEG.

Battery??
Telsa 2 = $12000 installed
Tesla gives a warranted amount of kWh at 38000kWh (about 7-9 years depends on premises)
$12000 at 7 years 5% quarterly = $511 per quarter = $2044 per year
Total cost plus interest over 7 years = $14300
However industry figures suggest net efficiency with Tesla 2 reduces by further 10% on top of normal losses

on a warranted per kwh basis = 14300/34200 = 41.8c/kWh

So each kWh Tesla 2 outputs will cost 41.8c/kWh

Hardly inspiring

 

[VPS]

My feed in tariff is 60.3 but I do pay 38c which is discounted by about 20%

Big refunds in summer

 

[Quickstatus]

My feed in tariff is 60.3 but I do pay 38c which is discounted by about 20%

Big refunds in summer

Unfortunately for most of us such feed in do not exist anymore.

However though the feed in was a lot greater and in many cases Gross rather than Net, the capital cost plus interest of solar panels were a lot greater then.
Factor that in and the net refund would be a lot less

 

[VPS]

Unfortunately for most of us such feed in do not exist anymore.

However though the feed in was a lot greater and in many cases Gross rather than Net, the capital cost plus interest of solar panels were a lot greater then.
Factor that in and the net refund would be a lot less

I've had them about 7 years and they have well and truly paid for the investment.

I do realise that they aren't available any more but I do like it

 

[Quickstatus]

I've had them about 7 years and they have well and truly paid for the investment.

I do realise that they aren't available any more but I do like it

Any issues over that 7 years?

 

[cove]

Batteries are still too expensive for a reasonable financial return in most cases.
Looking at doing a 100 kW system and quotes are being organized while we are overseas.

 

[Flying mermaid]

We couldn’t make the batteries cost effective. Our driving assumption was that energy costs will rise much more than people assume so the figures will look better over time.

We went for a system that would allow us to use all the energy produced for 6 months of the year, so undersized for our needs rather than over sized. We didn’t try to work it all out ourselves. Was happy to find a really good installer who knew what they were doing, who listened to what we were trying to achieve and came up with a system that worked. We elected to go for top end panels to maximise generation, given our bad aspect. Ours are 330kw panels and have a 3% annual degradation, rather than the standard 5%. Of course that comes with a cost, so not sure whether it is cost effective or not.

Cloud has a huge impact - I reckon we lose more than 10% to cloud and we have had a very sunny autumn.

 

[cove]

Perth and Adelaide get really good amounts of sunshine compared with many other cities in Australia.

 

[Quickstatus]

We couldn’t make the batteries cost effective. Our driving assumption was that energy costs will rise much more than people assume so the figures will look better over time.

We went for a system that would allow us to use all the energy produced for 6 months of the year, so undersized for our needs rather than over sized. We didn’t try to work it all out ourselves. Was happy to find a really good installer who knew what they were doing, who listened to what we were trying to achieve and came up with a system that worked. We elected to go for top end panels to maximise generation, given our bad aspect. Ours are 330kw panels and have a 3% annual degradation, rather than the standard 5%. Of course that comes with a cost, so not sure whether it is cost effective or not.

Cloud has a huge impact - I reckon we lose more than 10% to cloud and we have had a very sunny autumn.

I would have liked a W aspect than a NE as this would at least cover some of the most expensive period of the day.

That is the main saving grace - that the figues will look better over time
Undersize rather than oversize is good mantra in the era of marginal net feed in tariff

Your $27000 array would cost over 10 years at 5% interest (opportunity cost) $862 per quarter.
So if your electricity bill reduced by more than $862 per quarter you should be ahead, barring any issues that require further capital.

.....

Perth and Adelaide get really good amounts of sunshine compared with many other cities in Australia.

Thats a definite yes - mainly in summer, plus the relative lack of cloud cover days.

Perth: 7.61
Adelaide 7.68 peak solar hours in summer

https://www.rpc.com.au/pdf/Solar_Radiation_Figures.pdf
(Though 1995 figures)

 

[VPS]

Any issues over that 7 years?

not one