Solar Panels

[RB]

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

From this and other posts of yours, am I correct in assuming you are on a time of use tariff?-I think many people are not.
I understood the ballpark for Sydney is 3.9kw/h per 1kw system where Brisbane is 4.2, Melb 3.6, Adelaide 4.2.
I agree with your assertion that opportunity costs rarely seems to get considered.

 

[Quickstatus]

From this and other posts of yours, am I correct in assuming you are on a time of use tariff?-I think many people are not.
I understood the ballpark for Sydney is 3.9kw/h per 1kw system where Brisbane is 4.2, Melb 3.6, Adelaide 4.2.
I agree with your assertion that opportunity costs rarely seems to get considered.

Yes TOU. However average net costs after discounts = 25c/kWh (total consumption/total cost over the quarter)

The Peak solar hours differ depending on time of year. In the solar radiation figures link above December is 6.3 and June is 3.8 for Sydney. In a way it is better to calculate the worst case scenario for production which is in Winter.

 

[samh004]

In January we were generating around 80kwh per day, by April it’s dropped to 50kwh.

My figures are a little below that, but as my system is slightly less than a quarter of the size, it seems about right.

 

[Quickstatus]

My figures are a little below that, but as my system is slightly less than a quarter of the size, it seems about right.

That’s pretty good figures. You are still getting about 5kWh per installed kW at this time of year.
I expect that I will be slightly less at about 4.5

And a NE/NW aspect is about as good as it gets!!!

I notice you grid feed about 50% of your generation. What’s your feed in tariff?. Net?

 

[samh004]

I notice you grid feed about 50% of your generation. What’s your feed in tariff?. Net?

Only a relatively new system, so my FIT is a low 10.6¢ compared to my import at 22.48¢ and a service charge of 95.69¢/day.

Our primary goal is to work out how to best utilise what we generate during the day so it's not sold for peanuts, and to reduce power usage at night as much as possible.

We get hot water spikes early morning/late night so I've been reading up on a suggestion I read elsewhere of turning the hot water into essentially a battery (superheating water during the day with excess power that would otherwise be sold to the grid, the water then gradually loses its heat but not before solar has kicked in again so we no longer have to worry about the spikes when not producing). However, that would eliminate all power for other things, like A/C in summer.

The house is all IoT appliances and LED smart bulbs, so consumption is already at a respectable level.

 

[Quickstatus]

Sounds like you are on a flate rate tariff?

My off peak tariff is essentially the same as my feed in tarif. So there is no reason to move loads into generation period.

What system do you use to remotely control your appliances

 

[samh004]

Sounds like you are on a flate rate tariff?

My off peak tariff is essentially the same as my feed in tarif. So there is no reason to move loads into generation period.

Yes that is correct. Perhaps in the future I should look into a peak/off-peak rate.

 

[Quickstatus]

@samh004 , what solution do you use to control your appliances (which you mention are IoT enabled)

 

[samh004]

@samh004 , what solution do you use to control your appliances (which you mention are IoT enabled)

I use HomeKit as I'm an iOS person. So we have a hub connected to the router and I can control the lights (Hue) from another country if I like, I can also see when the garage door has been opened/closed (Merlin). We plan to get a NEST smoke alarm soon and expand to smart locks too, but don't see the point in having a smart kettle or internet connected fridge. I turn off the TV when I am not watching it, and it is new (last year) so not too harmful on the power bills. Our A/C isn't IoT but I have been investigating a Sensible or Tado for the future... though I'm keen on HomeKit support usually. We also have a Sonos One and look forward to Amazon Alexa coming online for more functionality soon.

 

[Flying mermaid]

We started off with Clipsal Minder when we built the house in 2000 and then upgraded it to Wiser 2. We pretty much just control the lights, some power points and fountains but could expand to other things if we wanted to. It’s been quite useful when the usage changes and we want to change what switch controls what light. Also the ability to turn all the lights off from the bedroom and upstairs and we have an automatic dim of all the lights at midnight.

 

[samh004]

We started off with Clipsal Minder when we built the house in 2000 and then upgraded it to Wiser 2

Looks like an interesting system/app... will be interesting to see the space moving forward as more companies decide who to partner with (i.e. exclusivity or all vendors).

 

[Flying mermaid]

Looks like an interesting system/app... will be interesting to see the space moving forward as more companies decide who to partner with (i.e. exclusivity or all vendors).

when we put it in there really wasn’t much around - the last few years has seen heaps more options (and cheaper too).

 

[daft009]

I put in a 8kW system at work with a 3ph inverter.

Has been great, from $800 bills per quarter we're down to $200 bills.

Being commercial we're using what we're generating pretty quickly I'd say though I didn't spend the extra on a smart metering

 

[leadman]

To the question on cleaning the solar panels.......

 

[Quickstatus]

To the question on cleaning the solar panels.......


View attachment 123653

It’s green!!

 

[Flying mermaid]

just had our first full bill since putting in the panels and the first since getting the feed in tariff. The bill starts from 19 Jan, but they only started the feed in from 31 Jan. this is in spite of having the panels generating from mid December and negotiating a feed in tariff in early Jan and using the same providers. I thought it would start on 19 Jan.... Anyway the net result was we had a bill $100 in credit, vs a bill for $1,281.84 this quarter last year.

Pretty happy with that. The next two quarters will be interesting. Pulling more from the grid now and that will go up exponentially once the floors get turned on. The pool dehumidifier is cutting in a lot more since the weather cooled.

 

[Quickstatus]

just had our first full bill since putting in the panels and the first since getting the feed in tariff. The bill starts from 19 Jan, but they only started the feed in from 31 Jan. this is in spite of having the panels generating from mid December and negotiating a feed in tariff in early Jan and using the same providers. I thought it would start on 19 Jan.... Anyway the net result was we had a bill $100 in credit, vs a bill for $1,281.84 this quarter last year.

Pretty happy with that. The next two quarters will be interesting. Pulling more from the grid now and that will go up exponentially once the floors get turned on. The pool dehumidifier is cutting in a lot more since the weather cooled.

Nice.
Going into winter will see perhaps a 50% drop in generation. The bill will depend on how you use the solar before its exported.

 

[Flying mermaid]

Nice.
Going into winter will see perhaps a 50% drop in generation. The bill will depend on how you use the solar before its exported.

once we turn on the floors we won’t be exporting any at all. We will be fiddling around with them to optimise usage. Generally we have them turn on about an hour before we get up (so the bathroom floor is nice ) and they turn off around 5ish. We generally have them on quite low, just to keep the floors pleasant and gas central heating is our main heating. Generally in the middle of the day with big windows facing north we don’t need heating, but if you get a gray foggy day it is a different story,

We want to turn the floors up a bit higher and use less gas, but I suspect we won’t be able to cover that, so will return to our normal strategy.

 

[Deleted member 29185]

To the question on cleaning the solar panels....... View attachment 123653

I wonder where that is? What kind of lunatic runs a power station like that?

 

[Quickstatus]

I wonder where that is? What kind of lunatic runs a power station like that?

Solar panels have competition who would have thought