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Do you have solar panels?

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The three most interesting things I got out of it was as follows,

1) In the lead-in piece prior to the interview with Mike Nathan, one of the interviewees advised that solar was now competitive with other forms of generation. If that's without the federal solar subsidy, that should be removed. Cost with the subsidy is around $1.20/watt of installed capacity.

2) He declared he pushed the envelope on the FIT cut an other information came to light. Push the envelope is a poetic choice of words. More than ever, I feel that other information that came to light was the contents of that envelope sent by Synergy to the 40c/kWhr FIT scheme participants in 2011.

3) Solar panel owners will not be targeted in isolation in any future increases in the fixed component of electricity charges. After the FIT fiasco, the government simply won't be game for some time.

http://www.abc.net.au/news/2013-08-16/energy-minister-not-committing-to-a-fixed-charge/4893730

I thought he spoke rather frankly bearing in mind the difficult situation he had put himself in.
 
Czechoslovakia joins Spain in taxing solar panels.


http://www.pv-tech.org/news/czech_senate_approves_renewable_energy_subsidy_cuts_and_10_solar_tax/
 

hello sorry for old thread reply but have you got the solar panels? i am looking to install solar panels on my home roof so please share your experience and tell about the cost of installation.
 
ClaudeOrtega said:
hello sorry for old thread reply but have you got the solar panels? i am looking to install solar panels on my home roof so please share your experience and tell about the cost of installation.
Click to expand...

My 5kw solar system was installed Friday just gone.

I went with a local company called Solar4Ever and found them to be extremely helpful & professional and they conduct their own efficiency testing on all products that they supply. I found this to be of most value when comparing output from the premium products, compared to product levels below that.

The installers were courteous & professional, the young guy (20ish) working even swept my garage clean, instead of sitting on his backside, when waiting for the senior installer & I to complete paperwork.

The cost was around $5,300.

In 2 full days of operation it has produced nearly 50Kw of which 30 something has gone back into the system. I have very little north facing roof space, which I am saving for a solar hot water system, so half the panels are on the western side & half on the eastern side. This produces 17% less power than if all were on a northern ceiling but for me this is unavoidable.
It has added another 8 months to the projected pay-off period.

We installed one now as my wife is pregnant with our first child and she is due in less than 3 months. With her being home for a year, instead of working, our power bills were set to sky rocket.
 
springhill said:
half the panels are on the western side & half on the eastern side. This produces 17% less power than if all were on a northern ceiling but for me this is unavoidable.
It has added another 8 months to the projected pay-off period.
Click to expand...

Depending on what you are paid for feed-in to the grid (FIT) it is not necessarily the case that the E - W arrangement produces a worse outcome than having all the panels facing north.

You will produce less energy in total, that is a given, but it will be spread more evenly over the day than if they faced north. That is, a north-facing array will have an output that if graphed looks like a classic bell curve with a peak at noon. In contrast, the E - W arrangement will not produce the same peak output, but will produce a lower level far more consistently during sunshine hours.

The practical effect of the E - W arrangement is that, unless you have a big peak in your power consumption around the middle of the day for some reason (which is unusual), then you will end up using a greater portion of your solar system's output within the house, feeding less into the grid and meaning that you also draw less from the grid in the morning and late afternoon.

If you are on a FIT that is paid a rate significantly lower than what you pay for electricity drawn from the grid then you'll actually be better off financially with the E - W arrangement in terms of your power bills (ignoring any installation cost difference for E - W versus all facing north).

If I were to install a new system today, then I'd definitely go E - W even if there was a large north-facing space available for the reasons I've mentioned. 8c FIT versus 26c for power drawn from the grid (current rates here in Tas, will be fairly similar in most states) - it's financially better to spread your output more evenly thus increasing the amount of it used within the house.
 
My 1.52kW system has just ticked over 7,000kW and should make 7,500kW by the third anniversary of its install.

It's now paid itself off.
 

Agree 100%, I had a system installed recently on the holiday home.
1600W of panels with 5KW 4 string inverter, all the panels mounted on the West facing aspect.
As panels become cheaper, I will add more strings on the East aspect and then the North.
 

Thank you for this perspective Smurf, it makes perfect sense and I appreciate the time taken to flesh the thought out.

My neighbour popped over earlier today to enquire about my system, I updated him with this permutation when I saw him over the fence just a few hours ago.

After the 3rd full day, I have generated 66.7Kwh and feed 38Kwh of this back into the grid.

Lucky those who first installed at the 40c per Kwh feed-in tariff!
 
Does anyone know if there is an advantage or disadvantage is splitting a 3KW system with 6 panels on each side of the roof......That is 6 panels on the East side and 6 panels on the west side.......it is being installed with 5 KW inverter.

I have heard it could add up to a 5 % disadvantage.
 

When you are using a single inverter all your solar panels should be at the same tilt angle and orientation otherwise there will indeed be a loss of power.
The actual quantitative loss will depend on your location's latitude, amongst other things.
 
No real hassle provided that the 6 panels per string is within the inverter's voltage specifications (that is, having only one set of 6 panels results in operation within the inverter's turn on limit, it's MPPT (Maximum Power Point Tracker) operating range and does not exceed its' maximum input voltage).

Eg If you have 6 x 24 Volt 200W panels wired in series (as they would be) then that will result in an operating voltage typically around 210V on the DC side of the inverter, dropping as low as 180V under some weather conditions and going up as high as 260V under open circuit (no load, eg due to failure of the mains power grid) conditions. That's not a problem provided that this is within the intended operating range of the inverter and that varies between models.

If the inverter has two MPPT's then it will operate at full efficiency despite two opposing panel orientations. If it has only one MPPT then it will still operate at well over 90% of it's optimum as long as it's wired as two sets of parallel strings (ie 2 x 6).

Don't, under any circumstances, allow someone to install a single string of 12 (or any other number) of panels wired in series with the panels facing different directions. That will pretty much kill the output of the system - it won't actually break anything, but it won't generate much power either. Suffice to say there have been more than a few installations by dodgy installers done this way.

As for the actual power output, you'll lose some output overall facing E or W compared to facing N, but with the advantage that you'll typically end up using more of your own power within the house rather than sending it into the grid. So, a bit less output but it ends up being worth more per unit of production assuming that your feed-in tariff (FIT) is considerably less than the price you pay for energy drawn from the grid as is usually the case with new installations in Australia.
 

Smurf, perhaps you can help me better understand this because my brain us struggling with it.
If an E-W orientation is chosen the total amount of PV energy produced annually for a given size of array will always be less than if the array has north orientation. Depending on the household energy usage pattern the proportion of produced PV energy used by the household might well be a bit more for an E-W versus nothern orientation but the total available PV energy for sale to the grid will be less overall. Whether the FIT is high or low I would still want to sell as much PV energy to the grid as possible.
 
Thanks for your help Smurf

The inverter which has been installed is a Solar Max S-Serie 6000S made in Switzland....The company I am dealing with only have one Inverter which is the series 6000 S....one size suits all......I may have to check out the inverter or speak to the installers who have not finished yet due to the rain here in Townsville.

All I can note from the manual is mention of Maximum power point tracking (MPPT, searching for the optimum operating point)....no mention of having two MPPT.
 
It comes down to electricity having a variable value (price) depending on when it is produced. That is true for both household solar and for large scale generation (power stations).

At the household level, for a new installation in most parts of Australia you'll be paid somewhere around $80 per MWh (8 cents / kWh) for what you feed into the grid (FIT). Meanwhile you will pay a higher price, commonly around $250 per MWh (25 cents / kWh) for what you draw from the grid.

The key point to understand here is that measurement is instantaneous. Eg feed-in 1kWh right now and you'll be paid 8 cents. Take back 1kWh straight afterward and you'll be charged 25c for it. The two are separate measurements - they don't "cancel each other out" or anything like that.

If your solar system generates power that you use at home, then you are saving around 25c for each kWh it produces at that time, thus giving a 25c value to each kWh generated. But if it produces power that just goes into the grid, well you only get paid 8c for it.

It is thus financially beneficial to correlate usage with production as far as practical since this results in a greater financial benefit from the solar power produced.

Suppose that you generate 5000 kWh over a 12 month period and use 2500kWh of it yourself. 2500 kWh x 25c = $625 plus 2500kWh fed in x 8c = $200. A total value of production of $825.

If however you produced 20% more, 6000 kWh, but fed the whole lot into the grid then you have 6000 kWh x 8c = $480.

So there is a definite financial benefit in producing power when you'll use it yourself, even if this comes at the cost of lower total output. Maximising production does not necessarily lead to maximising revenue.

Of course, if your motivation for generating power is something other than financial (eg environmental reasons or you just like the idea of generating power at home) then this doesn't apply. In that case face the panels north and you maximise total output. That said, even there it gets a bit complex - demand on the grid peaks during Summer afternoons and at this time supply has the greatest impact environmentally. So there's a benefit in maximising the mid-afternoon output of a solar system (ie face the panels West) in that case, partly offset by the production loss associated with them facing W rather than N. Overall, it gets complex if the aim is non-financial (eg to cut CO2 emissions) but what can really be said is that facing them N (maximum total output) or W (highest output when grid demand is highest) will be better than facing them E (which isn't optimum from either perspective).

The same logic applies to large scale power generation, especially hydro. Here's some data for a real hydro scheme.

Best efficiency, that is maximum power per litre of water used, is achieved with turbine output at 62 to 74% of capacity. Either side of that range efficiency falls off, and it falls off dramatically below about 52% at this plant. It falls off less seriously above the 74% level. And the long term supply of water (due to rainfall) is sufficient to operate the plant at 41% of its' capacity on average (ie the average output over many years).

Since this plant has enough storage to give flexibility of use, that is the dam is large enough to not spill even if the plant were shut down for an entire year, how to operate it becomes a question of price.

If the market price is moderate then running at optimum efficiency is the goal. So run 1 to 6 machines (there being 6 machines in this plant) at about two thirds of capacity thus maximising total output over the long term (using the water most efficiently).

But if the price is high well then efficiency doesn't really matter. Run it flat out to it's absolute limit, that's exactly what we do. Running at 100% capacity means a loss of output at some later time (since the quantity of water available is fixed). But that loss can be shifted to a time of low prices (eg middle of the night - just shut down the plant entirely if need be). So if we're selling at $100 per MWh then losing a bit of production at $40 per MWh some other time still makes sense financially. But if the market price is, say, $40 per MWh then there's no point running above the point of maximum efficiency, the sensible options being run at peak efficiency (or "efficient load" as it's known) or not run at all (save the water for use when prices are higher).

So the same underlying issue applies to power generation regardless of scale. If you're getting a low price then you need to focus on maximising efficiency. But at a high price, it's output NOW that really matters with efficiency being pretty much irrelevant.

With solar at home, typically you'll get a higher effective price by pushing production to a flatter profile throughout the day (E and W facing panels) rather than having a large "hump" in the middle of the day (panels facing N) which is fed into the grid at a low price.
 
noco said:
All I can note from the manual is mention of Maximum power point tracking (MPPT, searching for the optimum operating point)....no mention of having two MPPT.
Click to expand...
I'm not familiar with that inverter but if there's only 1 MPPT then I wouldn't be too concerned in practice. There will be an efficiency loss, but we're talking about a couple of % not something huge.

Suffice to say that I have two strings (facing different directions) on a single MPPT inverter myself, the reasons being purely economic (too little to be gained to make it worth worrying about).

As for MPPT, the principle is that:

1. The optimum voltage to operate the panels at is not constant but varies with light intensity and temperature.

2. As with a battery, the voltage of a solar panel is highest with no load (it's around 20.8V for a nominally 12V panel which has it's peak power typically around 17.5V) and falls as soon as a load is applied. Solar panels behave very similarly to a battery in an electrical sense when it's daylight.

So in layman's terms the MPPT just searches (constantly) for the optimum load to place on the panels. Too little load and the voltage goes up but the current goes down, thus leading to a drop in power output. Too much load (eg when it's overcast) and the voltage falls but current remains constant, also leading to a drop in power output. So the MPPT is simply searching for the "sweet spot" which gives the highest total power output under any given conditions (bearing in mind that light intensity changes more frequently than most realise - it's rarely constant for long).

It's like having a constantly variable transmission in a car. Not quite the same, but it's a similar principle. Keep the load on the panels (or car engine) at the optimum level for the conditions.
 

Smurf, while you explanations are interesting I struggle to agree with you. I will try to explain with a couple of charts.
The first chart is an estimated annualised average daily profile of the power output from a 6.0 kW PV array located at lat/long 37.5S/145E with a tilt angle of 38 degrees but with three different orientations North, West and East.


Now I think you are proposing that instead of orienting 100% of the array panels north it would be better to orient half of them to the East and the other half to the West. The next chart shows the combined output of this arrangement and compares it once more to the 100% north oriented array.


Assume for the moment that the household consumption profile exactly matches the output from the mixed E-W oriented array. By examining the areas between the green and purple curves of Chart 2 I think it is fairly obvious that an extremely large price difference between FIT and consumption price is needed for the E-W array orientation to be more cost effective than the 100% north oriented array.
It does't matter what kind of consumption profile is used, the conclusion will be the same.
 
Bintang said:
The first chart is an estimated annualised average daily profile of the power output from a 6.0 kW PV array located at lat/long 37.5S/145E with a tilt angle of 38 degrees but with three different orientations North, West and East.
Click to expand...
I was assuming a 22 degree tilt, since 38 degrees is pretty steep for a roof and installing a tilt frame offers no real advantage.

Here are some calculations for a 1kW system (to keep it simple) in Sydney. Output figures are annual AC generation.

22 degrees, facing North = 1388 kWh
38 degrees, facing North = 1356 kWh

22 degrees, facing East - West = 1239 kWh
38 degrees, facing East - West - 1142 kWh

For reference, here are the results if that system were installed in Darwin / Hobart.

22 degrees, facing North = 1559 (Darwin) / 1267 (Hobart)
38 degrees, facing North = 1456 / 1272

22 degrees, facing East - West = 1467 / 1089
38 degrees, facing East - West = 1333 / 1012

So at 22 degrees, the loss for E - W rather than facing N is 6% in Darwin, 11% in Sydney and 14% in Hobart.

At 38 degrees, the loss for E - W rather than facing N is 8% in Darwin, 16% in Sydney and 20% in Hobart.

So if we take an average situation, bearing in mind that most Australians live well south of Darwin and well north of Hobart, it's around an 11% loss (Sydney figures) as being fairly typical.

Looking at my own system, and I have panels facing E, N and W (total 6.69kW) then I've actually seen one of the two East strings running at over 80% of nominal capacity whilst the North string (1.36kW) was sitting on 130 Watts (ie 10% of capacity) around 9am. So there's a definite large increase in production prior to 10am having the panels facing East, and similarly after 2pm with panels facing West.

The above were calculated using Sunny Design (SMA).
 

I didn't know your location and guessed somewhere near Melbourne. Hence my choice of 38 degrees but of course if you are mounting on an existing roof you can't necessarily install at the theoretical best tilt angle for your latitude. Anyway, I re-calculated some profiles based on 22 degrees and report the results as AC output from the inverter. I calibrated my models against your 1388 kWh for 22deg North for which I needed to use an inverter effificiency of 91.3% along with an assumed total de-rating factor for the PV array of 85%. Here are the results:


The first chart shows the sort of big difference you mentioned between the outputs of the East and West facing arrays at around 9:00am. Its not quite as large as your observed 8:1 ratio but then again this chart is an annual average.



Once again when the E-W facing array profiles are combined 50/50 the resulting profile is not flattened very much at all relative to the 'bell' shape of the north facing array profile. In fact the profiles have very similar shape except that the E-W profile has a lower peak. So my conclusion is that provided I have the option to install with a north facing orientation I would never choose the split East-West orientation.
 
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