I read somewhere that the efficeiency of panels and inverters varies with the ambient temperature and that some inverters are more efficint at coping with this than others. Can anyone advise me?
PV system efficiency
(12 posts) (8 voices)-
petanque
MemberConsidering the variable conditions that most systems may operate under you may need to give more information.
A System at Alice Springs would be under very different conditions to a system in Hobart.
I would imagine the differences involved would be modest.
Posted Tuesday 28 Apr 2009 @ 6:33:20 am from IP # -
petanque
MemberSo you would be more interested in 30 to 50 degree performance rather than 0 to 20 degree performance.
I would imagine that the differences between brands of the same style of panel would be modest.
I have heard it suggested if it is possible to have a larger air gap between the panel and the roof there is better air flow and so the panels are a bit cooler.
Posted Tuesday 28 Apr 2009 @ 7:16:59 am from IP # -
Sunshine
MemberAnt,
The inverters efficiency isn't affected very much by ambient temperature, but the temperature of the panels causes a considerable power output variation.
Generally mono and poly silicon panels have similiar temperature performance (i.e. power output drops as panel temperature increases), but amorphous silicon panels power output is very stable when ambient temperature increases.
However, amorphous silicon panels aren't as efficient overall so you need more roof space to get the same power output compared to mono and poly silicon panels.
For some people roof space is limited.Posted Tuesday 28 Apr 2009 @ 9:24:26 am from IP # -
rsigmund
MemberHave a look here at this site. It allows you to compare (for efficiency) different Panels, Technology and Mounting systems. The site takes a bit of getting used to but it is quite good - let me know if you have any questions.
http://www.dkasolarcentre.com.au/
I am not sure about inverter efficiency and temperature. Generally the transistors inside the inverter rely on air heating (fan assisted). That means that they are hotter than the ambient temperature.
Posted Wednesday 29 Apr 2009 @ 12:11:26 am from IP # -
petanque
MemberIt sounds like in an ideal world the inverter would be placed in a shady spot that there is likely to be some air flow.
I have a sunny boy inverter and it seems to have a definite transformer hum and is intrusive at times
If you live in a hot area the larger panels may have the advantage that they will shade more of the roof and keep the roof space cooler in the hot weather.
Posted Wednesday 29 Apr 2009 @ 12:18:13 am from IP # -
sonofdad
MemberThe heat tolerance (or temperature coefficient) of various solar panels can and does play a very big role in the output of your system over time, and in the lifespan of your system the difference can add up to mWh's of electricity. At this stage thin-film modules will easily maintain the highest output in heat - they generally will only lose 0.20 - 0.25% per degree celsius that they rise above 25 degrees (panel temperature).
Mono or polycrystalline modules will generally be around the 0.45 - 0.50% per degree C mark (the worst I've seen so far being -0.55%/C) however of the pure crystallines, Sunpower lead the pack there with a rating of -0.38%/C).
The Sanyo HIT's are a step up from the Crystallines, being -0.30%/C, and are easily the best of both worlds at the moment, although they are generally dearer as well. Being a thin-film/monocrystalline hybrid through allows them to have some of the best characteristics of both.
I would estimate that a 1.0kWp thin-film system in most warm Australian areas would generate between 80 - 160kWh more per year than an equivalent crystalline.
As for your inverter, mounting it under shading is a must, especially with the summers that we have. The SMA inverters are weatherproof but being on an exposed northern or western wall in 38+ degree weather is not going to do your inverter any good
Posted Saturday 2 May 2009 @ 11:31:40 am from IP # -
MaryJane
MemberHi
We installed 4kw of grid connected SunPower 215 panels on our roof in Perth last year. Efficiency really drops off as the temperature increase. (The panels being black do get hot.) You can see the heat coming off them during a hot day. Consequently even though the sun is higher in the sky and there are more hours of daylight during summer, the thermal characteristics of these types of panels means our electricity production plateaued once we hit December. Here we are in May and production is just starting to drop. Not bad.We have produced 6.757 MWh in 12 months (just checked) Our roof is due north and unshaded.
Some of the best instantaneous production rates have occurred on mild sunny days with some cloud. As the sun passes behind the cloud there seems to be a lensing effect and we have achieved achieve peak instantaneous of 5300 watts. (Must get out more and stop watching inverter display)
cheers
MJPosted Tuesday 12 May 2009 @ 8:14:12 am from IP # -
lotech
MemberI've wondered about this a lot (yes, obvously I need to get out more too MJ
and I think it's another good reason to look at using panels as an eave or vernandah - effectively giving them a couple of functions and allowing better airflow and temperature control. I'm not sure if they can be mounted so that you generally achieve a weatherproof surface as you would with solid eaves though - logic sort of says no, and that you'd need to put some form of lining between them and the pergola/verandah battens etc - which defeats the original purpose! Has anyone done this sucessfully and made a weatherproof area underneath?
Posted Wednesday 27 Jan 2010 @ 8:13:23 am from IP # -
Greg
Memberlotech - there are several solar systems around that boast a weatherproof feature. Here is one http://www.pvsolartiles.com.au/ and I'm pretty sure there are others.
Posted Wednesday 27 Jan 2010 @ 9:08:41 pm from IP #