Correct orientation of solar panels

[fassi]

Can someone please help me out with some advice. I have a colourbond roof (5 deg pitch) with a ridge line running north south (12 deg East, to be exact). Today I had a 2.28kw system installed and was told that it was not practicle to stand them facing that direction on brackets, in say groups of four or six. Insteadd the installer advised to face them west (282 deg roughly), hence running them in one long line. Is this correct or should I insist on facing them north. Reason given for different direction was that the sun production in summer would more then make up for lost production in winter? In NSW peak power costs are between 2pm and 8pm and he stated due to me being on net metering it is better to make the KW in the 2pm - 8pm time bracket. I live in Lake Macquarie NSW. Any advice would be appreciated. If I do need them altered, will it be a difficult task.

thanks

Brett

[c*p]

Hi Brett. For the output of your system against orientation, you can check out the tables in the document referred to in the "sticky" post above. Look to the back of the document and find a city with a similar latitude to yours. I note Lake Macquarie (not Port Macquarie) is not too far from Sydney to use the Sydney table.

My understanding is that normally, you want your panels tilted at least 10 deg to gain self-cleaning, so on a 5 deg roof you might expect a tilted frame anyway. This may not be the case if you are concerned about high wind or aesthetics and will compromise for these reasons.

Looking at the table for Sydney, the best output (100%) is facing (within 10 deg of) North and tilted at your latitude which is 34 deg for Sydney and a bit less for Lake Macquarie. For Sydney, a flat panel will output 87% over the year. One tilted North by 5 deg will output (interpolating between 0 deg and 10 deg) 91%. A panel tilted 5 deg at azimuth 280 deg will output about 88%: just slightly more than a flat panel. Thus you are losing 12% of your annual output by not tilting North.

These tables only consider total annual production. My own calculations have shown that panels tilted West or East (by a typical pitch angle of 20 to 30 deg, and ignoring weather patterns such as tendencies to be more cloudy in the morning) will outperform North panels over the Summer (in Melbourne), but greatly underperform in Winter, resulting in the annual underperformance as indicated in the tables. You can see this in the DKA live data. If you look at the Live System Information for the Solar Compass (system 16), and click for 12 months, the plot is messy. If you click on the plot to look at the averages for 2 month periods, then to the 1/12 and 1/3, the flat panels outperform North, and the East and West only slightly underperform. For the other periods, North is significantly better. Further South, in Melbourne, the effect is stronger so the East, and West actually do outperform North in high Summer.

Another consideration is mutual shadowing. If you tilted the panels North, you would need to space them apart by about their length so the "front" row of panels did not significantly shadow the next row and so on. In our situation, we mounted the panels flat to the roof which pitches 26.4 deg West. Although this lost us about 14% of output, it meant two things: (1) the panels were almost invisible, especially from the street, (2) we could actually put on more panels due to the elimination of the need to space the rows to avoid shadowing eachother.

The optimum time of power production depends on your usage pattern, your likelihood of generating more power than you use (exporting) and whether you get a premium for power exported. It also depends on the time of day cost of your power. If you get a premium for exporting (paid more than your power costs you), then it can actually be better to MISMATCH your usage and generation. It is better to export and import, say, 2kWh during a day rather than match your usage and generation and balance them out. This is because the 2kWh you import will cost less than you earn for the 2kW exported. If you will not export significantly, then I agree - you are better producing when the kWh cost you most. You indicate peak time as 2-8pm. In Melbourne (AGL), peak is 3-11pm weekdays. This consideration is very dependent on your own circumstances.

In summary, it is up to you what you choose and why. Mounting flat to the roof and not tilting North will cost you about 12% of possible output (per panel). It will leave your panels neatly flat to the roof, and avoid having to space tilted panels to avoid shadowing, so you may actually fit more panels and more than make up the loss of 12% that way. In terms of time of day production, you will need to decide, based on your usage pattern, premium paid and likelihood of exporting, and time of day cost of importing your power. c*p

[zarker]

Hello there, i had just installed solar panel at my home but i have no any idea about orientation of solar panel. Please anyone here can update me.