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Started 10 years ago by bootsnall
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solar panel

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bootsnall
Member

After waiting for too long I am now taking the plunge and installing 4KW of solar panels on my tile roof of 20 degrees slope facing due west as I have no other roof space except this. This is in Brisbane. I have no shading problems.

Your comments are invited.

Here are the details:-

Mono crystalline premium high grade Solar Panels 250W (17.5% cell efficiency). Operating temp is 40-45 degrees not the usual 20-30 degrees and these are put in commercial solar farms.

Made by a Spanish Company in China called Solarig. Panels are called Stream.
Web site of company is http://www.blueskysolarenergy.com.au

Inverter is a Diehl AKO 4600 S with 10 year guarantee with optional extra to 20 years.

Posted Monday 4 Apr 2011 @ 4:26:02 am from IP #
rockabye
Member

Sounds like you have already decided so all you can do now is sit back and watch what happens. Make sure you take meter box readings before switch on and regularly once it's running. If you don't measure it you can't manage it.

To make the most of any solar system you need a full energy audit. It is pointless putting in clean energy if you are wasting energy at the same time. Have you done this yet?

Posted Monday 4 Apr 2011 @ 4:29:58 am from IP #
Russell Moore
Member

West is definitely not the best direction to face the panels, you will have the panels working at their peak in the hottest part of the day, not good, remember panels derate at approx' 1/2% for every 1ºc rise in their temperature. Also in summer there is a tendency for the mornings to be cooler and clear, and then cloud builds up in the afternoon, such as thunderstorms etc.

Could you step frame them across the roof to face them north?

I have never heard of your panels or inverter, I will investigate.

Posted Monday 4 Apr 2011 @ 5:00:00 am from IP #
bootsnall
Member

I have 10 days cooling off from yesterday. I would appreciate any feed back.

Roof temp is usually 40 + degrees as I have solar heating for my pool and can monitor roof temp. That is one reason I chose these as many panels lose efficiency once they pass the 30 degree mark but these panels start to lose after 45 degrees panel temp.

I had never heard of these panels etc before but they seem to be much better than what I was looking at nearly 12 mths ago in terms of performance etc.

I have been checking my electrical efficiency usage and have substantially reduced my usage. My next step is to get my aircon changed to tariff 33 instead of tariff 11. Pools pumps are on 33 - 1 for filter - 1 for solar.

I understand about the west facing panels but east is worse & east & north on my roof are also taken up by the solar pool heating. Unfortunately what's left of my north facing area is taken up with solar HWS and is not very large and is not able to be used.
If I step framed them to face north that would reduce the number of panels and may cause other problems with wind damaging them. But I am no expert.

Posted Monday 4 Apr 2011 @ 5:58:19 am from IP #
cw nsw
Member

bootsnall, suggest that you carefully read the CEC consumer guidelines & also check that the panels you propose to install are on their approved list - if not then it may be very prudent to cool off

http://www.cleanenergycouncil.org.au/cec/resourcecentre/Consumer-Info/solarPV-guide

admittedly west is not ideal, however some of us who don't have a northern option still get good performance from our systems

Posted Monday 4 Apr 2011 @ 6:36:52 am from IP #
Jeffbloggs
Member

Bootsnall
Chk out this site for a calculation with your proposed PV orientation. Select region and city bottom right and then enter size and orientation on input page. Compare with PV facing north. http://rredc.nrel.gov/solar/calculators/PVWATTS/version1/

Posted Monday 4 Apr 2011 @ 7:50:06 am from IP #
Russell Moore
Member

Which comes out at a 13% drop in output from 0º as opposed to 270º orientation, using the PVWatts site for Brisbane. Spread this out over 25 years, and it can be quite a bit of money.

Posted Monday 4 Apr 2011 @ 10:50:57 am from IP #
Benny
Member

I'm surprised no one has challenged the claim that these cells "only start to lose efficiency after 45C". If thats what the manufacturers/sellers claim then I would be skeptical right away. From my understanding ALL solar cells are given their specified output at 25C (cell temp, not ambient temp) and if they are made of Silicon (and monocrystalline) then ALL cells derate at a regular 1/2% per degC. This doesn't start at any particular temp - it applies at all temps and even means output increases if you cool the cells below 25C. Different technologies derate at different rates, esp thin film which are only 0.1-2% per degC but again its at all temps - it doesn't "cut in" at a particular temp. So unless your cells are specified at 45C ambient, be very wary of the hype. can you get a reference from the supplier as to WHY their cells are so special ?

Posted Monday 4 Apr 2011 @ 11:45:44 pm from IP #
rockabye
Member

My Unisolar 64W amorphous cells are rated at 49 deg C which is one reason why they outperform the mono xtals.

Posted Monday 4 Apr 2011 @ 11:56:23 pm from IP #
bootsnall
Member

Panels and inverter are on approved lists.

Not sure about temperature but here are details of the panels at the following http://www.blueskysolarenergy.com.au/pv-panel-info.pdf model is SE250M-33/D

I understand the loss of performance in having a west facing panel but it is either that or nothing so I'd prefer to offset my growing electricity bill cf having to pay for it.

Posted Tuesday 5 Apr 2011 @ 12:42:57 am from IP #
Russell Moore
Member

bootsnall, I actually compared two systems in Brisbane on pvoutput.org (eilly and Rob F West) eilly's panels are facing north, Rob's facing west, both systems have been up for around 307 days, the difference in output is about 22% in favour of eilly's.

I also did some rough calculations on how far apart you would need to space your panels if you step framed them, and they were placed in landscape position at 24º elevation from horizontal. This would give you full sun from 8am to 4pm onto the panels in the middle of winter. The spacing is 725mm from the back edge of the 'front panel' to the front edge of the next row. So yes, you would lose a fair bit of roof space, but that said, it would be better for keeping the panels cool.

If you go with the panels framed down onto the roof, try to get the maximum spacing under the panels as possible, and if possible set them landscape, so as there is an obstruction free path up the roof for convection air currents.

Good luck, Russell

Posted Tuesday 5 Apr 2011 @ 2:02:21 am from IP #
bootsnall
Member

Wow you guys know your stuff. Thanks Russell.

Has anyone checked the panels for temperature degradation and the statement about 45C being when output degrades? I'm not sure how to go about doing this. Maybe it is on the below chart I refer to.

There is a chart on http://www.blueskysolarenergy.com.au/pv-panel-info.pdf model is SE250M-33/D showing Characteristic Curves and I'm not sure how to read that. It also says NOCT (Nominal Operation Cell temperature) is 45C +or- 2C and I am unsure what that means.

Panels are also 1064 x 1590 x 50 so they are a little larger than normal or am I mistaken here?

I certainly don't want to be taken for a ride by anyone & there are lots of cowboys out there.

Thanks everyone for your helpful inputs to date - I really appreciate them.
Barry

Posted Tuesday 5 Apr 2011 @ 5:27:48 am from IP #
swanning_it
Member

bootsnall, you've been misled a bit over the temperatures.

Off your link above, the fine print at the top (just under Technical Datasheet text), indicates the ratings are indeed at STC (1000W/m2, 25 degree C cell temp and 1.5m/s wind). At the bottom right, it lists the temperature coefficient at minus 0.5% per degree C rise.......or in fact nothing wonderfully unusual.

I'm assuming the statement about 45 degree C being the "operating" temperature is referring to the NOCT (nominal operating cell temperature), which is not what it sounds like. The NOCT is a cross reference to Standard Operating Conditions (SOC), which are different to STC and determines the open circuit cell temperature at 800W/m2 insolation, ambient 20 degree C and 1m/s wind. They are two different parameters which should not be mixed up. There is also another common rating which you will see from time to time (because panels are sold worldwide and generic specification sheets are used), which is PTC (PVUSA Test Conditions) which are different again (1000W/m2, 20 degree C ambient and 1m/s wind but at 8m height above ground or at least I think it was 8m....memory not too flash these days)

EDIT: Sorry, I just looked it up, 10m above ground, not 8.

I might also say, that your proposed panel will indeed derate by 0.5% per degree C rise above 25 degrees AT THE CELL, not ambient. Remember that NOCT figure of 45 degree C was at an ambient of 20 degrees C. At an ambient of 35 degree C, you can realistically expect pushing 60 degree C at the cell.

Posted Tuesday 5 Apr 2011 @ 7:15:18 am from IP #
Russell Moore
Member

Standard panels are about 1600mm x 800mm, that is the size I used when calculating spacings.

Posted Tuesday 5 Apr 2011 @ 7:28:04 am from IP #
amun-ra
Member

swanning_it am 1.5 does not refer to wind speed it is the amount of atmosphere light has to travel through to get to your panels when the sun is low in the sky. am 1 when the sun is overhead middle of the day am 1.5 later in the afternoon correct???????????

Posted Tuesday 5 Apr 2011 @ 4:08:02 pm from IP #
swanning_it
Member

Thanks amun-ra for the correction. That makes more sense with the 10m above ground bit for PTC. I must admit, I never consider that parameter when making comparisons. I think there is also a correction for panel elevation under the SOC parameters. Tilt of 45 degrees or something....I'll have a look for it.

What I did find when I looked for the height above ground though, is that the NOCT is shown on a lot of generic international documentation because it is required under the California rebate scheme for PV installations, which sort of explains why it was shown in such big type on that data sheet linked to above, with little supporting explanation. The whole sheet was developed around STC with the NOCT being shown just for the rebate in California (and perhaps elsewhere as well).

Posted Tuesday 5 Apr 2011 @ 8:36:37 pm from IP #
swanning_it
Member

Just had a bit of a look and it seems;
1) under SOC, the 1 is indeed 1m/s average wind speed with panel tilt of 45 degrees;
2) under PTC, the 1 is also 1m/s average wind speed, but at 10m above ground; however
3) under STC, the 1.5 is Air Mass (AM) coefficient as decribed by amun-ra.

As a curiosity, the PTC stands for Photovoltaics for Utility Scale Applications, Test Conditions. PVUSATC or for short PTC which was decided specifically for California but now seems to be widely used across the US.

So I guess how this all relates to the OP, is simply the NOCT is pretty much irrelevant unless you live in California.

Posted Tuesday 5 Apr 2011 @ 9:21:40 pm from IP #
bootsnall
Member

Given that these panels are:-
rated @ 250w
bigger than standard size 1590 x 1064 cf 1600 x 800

Then the larger size is what makes them produce more wattage.

And given that they are on the west side (the only side I have available) they are not such a great buy at $14999 fully installed.

Has anyone got any better suggestions as to what are the best panels to suit me and a reliable supplier to do the job in Brisbane.

Thanks for the input so far - my eyes are being opened!!!!

Barry

Posted Tuesday 5 Apr 2011 @ 11:03:50 pm from IP #
rockabye
Member

Look in these threads as a lot of this ground has already been covered.

http://www.ata.org.au/forums/topic/beginner-after-advice-solar-panels

Some good info here including recommendations

http://www.ata.org.au/forums/topic/thankyou-ata-members

Posted Tuesday 5 Apr 2011 @ 11:18:30 pm from IP #
Russell Moore
Member

Barry, seeing that the panels will be outputing in the hotter parts of the day, have you thought about Sanyo HIT/HIP panels? They are not as effected by high temps as most other panels, amphorous excluded, in fact from what I have read they are a cross between the two.

Posted Tuesday 5 Apr 2011 @ 11:21:46 pm from IP #
bootsnall
Member

I monitor the test centre in Alice Springs http://www.dkasolarcentre.com.au/flash/graphing.html every now & then. It is quite informative and notice that these Sanyo panels seem to be there under another name.

Posted Wednesday 6 Apr 2011 @ 2:09:42 am from IP #
bootsnall
Member

I have exercised my 10 day cooling off period and canceled the contract with Blue Sky Solar Energy and I am now looking at the following options on a tile roof in Brisbane @ 20 degree slope WEST facing 270 degrees (only choice sadly with around 12 % loss)

Any further feedback would be appreciated. You guys are awesome with your knowledge and I really appreciate what you have given me. I do not feel deterred by the western orientation as it certainly appears to out-perform the eastern here in Brisbane.

Option 1 4.2 Kw $21485.00 Australian Natural Energy (RECs X 5)
20 X Sanyo HIT. 210W Mono-Crystalline Silicon Solar Panel, DC output, high efficiency cell of 18.9% and module of 16.7%. Dimensions 1580mm x 798mm x 35mm, Weight
15.5kg, 25 year power output warranty.
SMA 4000W Transformer Less Inverter with LCD display, 4200W maximum DC input,
240V output, 97.0% efficiency, Dimensions W-470 x H-445 x D-180, 5 year warranty.

Option 2 4.18 Kw $13950.00 Australian Natural Energy (RECs X 5)
22 X Suntech 190W Mono-Crystalline Silicon Solar Panel, 24V DC output, high efficiency
14.1%, Dimensions 1580mm x 808mm x 35mm, Weight 15.5kg, 25 year power output
warranty.
SMA 4000W Transformer Less Inverter with LCD display, 4200W maximum DC input,
240V output, 97.0% efficiency, Dimensions W-470 x H-445 x D-180, 5 year warranty.

Option 3 4.7 KW $17799.00 Energy Matters (RECs X 4) Installation after 30 June 2011
20 X REC Solar REC235PE-BLK
20 X 235w Sanyo HIT panels (18.5% cell efficiency)
SMA SB5000TL-20

Option 4 4.23 KW $14599.00 Energy Matters (RECs X 4) Installation after 30 June 2011
REC Solar REC235PE-BLK
18 X 235w Sanyo HIT panels (18.5% cell efficiency)
SMA SB4000TL-20

Option 5 4.23 Kw $14999.00 Blue Sky Energy (RECs x 5)
18 X Solarig Stream 235 Kw 17.5% cell efficiency
Diehl AKO 4600 S

Posted Sunday 10 Apr 2011 @ 11:32:56 pm from IP #
rockabye
Member

My NW facing system suits my locale as we often get a lot of morning cloud where as in the late afternoon it is usually fine and the system keeps working right up to sunset.

As for the 12& loss, try the glass half full view and think of the 88% gain

Posted Sunday 10 Apr 2011 @ 11:48:36 pm from IP #
Russell Moore
Member

Best value for money would be option 4 with the Sanyo panels, although option 3 with the Sanyo panels and the SMA5000 looks good as well, and would give you room to expand a little later on, if you have the space.

I haven't found an east facing system yet in Brisbane, on pvoutput.org, but I did find two systems, one NE (Zion)and one NW (Chords PV), Zion has 353 days of records, Chords 316, so not quiet an accurate comparison. The difference in output being about 15% in favour of Zion. This concurs with my thoughts that east of north is better than west of north, all else being equal.

What ever you do, I hope you have fun when you join the PV club, Russell

Posted Monday 11 Apr 2011 @ 12:37:09 am from IP #
rockabye
Member

My next 1kW will be on the NE face and will be on a separate inverter so I will be able to make direct comparisons after that. Either way you won't regret doing it.

Posted Monday 11 Apr 2011 @ 1:08:25 am from IP #
bootsnall
Member

I like the Sanyo HIT because of efficiency and the fact that they are producing more than their stated output as well as high temp efficiency & panel efficiency of 18.5%. The 235w panels will not be available till late June or early July.

Has anyone had experience with Energy Matters instals in Brisbane? Comments are welcome.

Or are there any other installers of Sanyo HIT in Brisbane that anyone knows of.

Posted Monday 11 Apr 2011 @ 1:44:17 am from IP #
bootsnall
Member

Option 3 RECs are -$7420 leaving $10064 for panels, inverter, installation

Option 4 RECS are -$7735 leaving $7179 for panels, inverter, installation

Posted Monday 11 Apr 2011 @ 2:43:43 am from IP #
bootsnall
Member

OOPS made a mistake on RECS

Option 3 RECs are -$7735 leaving $10064 for panels, inverter, installation

Option 4 RECS are -$7420 leaving $7179 for panels, inverter, installation

Posted Monday 11 Apr 2011 @ 2:48:46 am from IP #
Buzzman
Member

Barry, I do NOT mean to be 'negative', nor to deride you or chastise you concerning your 'lifestyle choices'.... but if, as you say, you have a 'growing energy consumption' then I would VERY SERIOUSLY suggest you should avial yourself of a full home energy assessment to establsih waht's USING the power in the first place, and to suggest ways this could be (practically and cost-effectively) reduced.
This should be the FIRST principle, not the last!
Once you have made all the 'alternative' energy saving solutions, then and only then should you be lloing to offset your consumption.
Offsetting a 'wasteful' consumption pattern (as yours would appear to be...cough...cough) is really defeating the purpose of installing RE in the first place,
Remember the old adage: Reduce. re-use, recycle.
What came first???
Prease consider, as Mr Miyagi might have said....

Posted Monday 11 Apr 2011 @ 3:21:05 pm from IP #
bootsnall
Member

Thanks for your advice Buzzman - its good to be reminded of this.

I do have quite a bit of power being used despite having solar HWS and gas cooktop.
I have a pool with 2 pumps 1.5 hp for filtering running from 2-4 hours/day depending on the season and 0.98hp running the solar heating which turns off at a predetermined temp. But both of these are on Tariff 33 and cost me $60-70/qtr.
We have 1 fridge & 1 freezer with LCD TV and energy saving bulbs everywhere we can. I also have a power monitor and can see the power hungry devices.

My bill runs between 20Kw in winter & 30 Kw in summer. Winter is less as we get free woood and use the wood heater to heat & cook on. We have 2 aircons but try to use these sparingly. I am going to get these changed over to Tariff 33 asap if that is feasible.

Yes you may be shaking your head but so am I wondering what my electricity gobbler/s is/are. We use the gas to boil water for tea/coffee as a jug is power hungry. And we rarely use a clothes dryer. And we have the dishwasher & washing machine too but wait till we get full loads. And I'm still scratching my head at why so much. I use less than before but the bill keeps climbing.

Posted Tuesday 12 Apr 2011 @ 3:39:16 am from IP #

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