What can we really expect with solar?

[T1 Terry]

The Voltage was about 26volt and the cells were about 50%
The air con was pulling about 50 amps @24v

PWM or MPPT controller? If there were clouds about and 3km from the ocean the solar reflection for sure. Some times had more than the advertised watts from the 3kW solar system on the house in Lake Illawarra and we were approx. .5km from the lake but the very narrow channel, the main body was probably 3kms or so away and the ocean about the same distance. Wasted over 12 mths of data collection when I realised the effect was so significant as the was no way of knowing if solar reflection was happening during part of a day or not, so the data was useless.
I don't think the Murray is wide enough to have much effect here in upper Mannum but cloud edge effect is a definite and it can last for 5 to 10 mins sometimes.

The load effect on panel output seems to be a definite as well, but only with PWM controllers running solid state relays and lithium batteries as far as I have seen to date, no ideas or theories available for that one yet, more time to do more tests with different type controllers and loads but definitely there with larger solar systems. The theory about PWM controllers being limited to the advertised panel output and therefore 70% capacity gets severely squashed on these occasions but determining if it's cloud edge or reflection or just why is yet to be determined.

T1 Terry

[Toolman]

60 amp PWM controller, no SSR , 400 ahr @ 24v Winston Lithium and it probably did last more than 10 mins
It seemed to happen not long after the cloud came over

[T1 Terry]

That poor controller must have near been in melt down with close on 90 amps running through it for 10 mins. In most cases where the solar feed goes through the controller they have current limiting or simply shut down to protect the IGBT from over heating so most people would only see the current clipped at around 66 amps and not realise there was more available. The big cables and some where for the current to go makes all the difference as often the panels are so hot the max power voltage is below battery charging voltage so without a load to hold the voltage down the panels won't put out their best.

T1 Terry

[Busman]

The Sunstar solar reg tapers at 130% of rated amps or 78 amps so there is something wrong here, either the SS is not tapering, in which case I would be carrying a spare ! Or something else is afoot.

[Toolman]

I have fitted a fan to my SunStar and it was about 55 degrees at the time, those conditions are something that I dont expect to see for very long or that often
The SS have a high temp shutdown at 80c so they must be very rugged.

The small board is a PWM temp controller for the fan:
http://www.ebay.com.au/itm/281852962551 ... EBIDX%3AIT

[jon_d]

I always admire neat installations.

[T1 Terry]

Very high tech on the fan controller, I just use a thermostat designed for 50*C with a 5*C hysteresis (on at 50*C off at 45*C) and mount is close and above the heat source and the fan above that so the heat is drawn past the thermostat... but I do like the high tech look of it.
I wonder if the SunStar actually current limits or heat limits and that is why you got away with the over load. The catch 22 of current limiting to avoid over heat is the rapid switching required for current limiting seriously increases the heat generated.... so heat monitoring is possibly the better option. As the solid state relays we use are rated at 100 amps continuous and 125 amps short term over load and 100% peak over load, the fact we build the systems with a 50% safety margin means we really don't need to current limit, just temp control seems to be enough.

T1 Terry

[Toolman]

That little fan controller comes on slowly @ 35C and ramps up speed as the heat increases, was only $13.70 and a fun thing to play with, defaults to full on if the smoke comes out. Not many solar controllers have as big a heat sink as those SunStars and they obviously work well

[T1 Terry]

That little fan controller comes on slowly @ 35C and ramps up speed as the heat increases, was only $13.70 and a fun thing to play with, defaults to full on if the smoke comes out. Not many solar controllers have as big a heat sink as those SunStars and they obviously work well

Gotta link to these fan control boards? Is the temp function adjustable?

T1 Terry

[BruceS]

Looks like this'n?
http://www.ebay.com.au/itm/DC-12V-24V-2 ... 1852962551