#1 Nov. 22, 2015 06:35:16

From: Southend
Registered: 2012-08-01
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Aurora 3600 Twin-string inverter

Does anyone else have one of these? Without my monthly ‘Performance Ratio’ particularly showing it up, my Aurora 3600 seems to have been playing up since about a year ago.

From my humble circuit-clamp monitor, I've noticed that the problem relates to it starting up at dawn. It needs about 95W of dawn light to do so (see Bart's post about detections of overnight ‘reverse power flows’ http://www.microgen-database.org.uk/forum/topic/50/?page=2 ).
But if there isn't that much light for a while after dawn, the inverter gets progressively less likely to start-up until later in the morning. If there's drizzle or rain in the morning, it may not start until the rain stops.

This is in fact the driest district in the UK. But on a couple of notably rainy days it didn't start-up at all the whole day :-(

Economy 10 tariff provides 6.9p/kWh off-peak import between 12am-5am, 1pm-4pm and 8pm-10pm; http://www.pvoutput.org/aggregate.jsp?id=21047&sid=18934&v=2&t=m on approx. 63% off-peak usage, 22% solar usage, and 15% peak-rate usage.
1,900kWh annually is exported, mostly in summer, on approx. 3,200kWh generation. Approx. 4,500kWh/year is imported, mostly for (a) winter and springtime off-peak Storage Heaters, and (b) off-peak hot water Immersion heating (which is “dumb”, i.e. not linked to the solar PV).
PV array is split East-West. Income is from Phase II 21p/kWh Feed-in-Tariff plus smart metered 3.2p/kWh Export Tariff.


#2 Nov. 24, 2015 15:15:33

Registered: 2011-12-08
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Aurora 3600 Twin-string inverter


1. Is the red fault light showing on the inverter?

I have an SMA 3600TL. There's probably been 4 or 5 days over a 4 year period when I've had zero production.

My (twin) array has an earth leakage fault on one string (probably caused by one of the DC cables touching the wet roof). I've tried to get quotations to get it fixed without much luck. When it's been wet overnight and especially windy then sometimes it won't start in the morning because of this. The remedy is to turn everything (AC and DC) off, start it on the good string and then turn the faulty one on when it has started. It tests for earth leakage before startup and a red light shows the fault (plus the error message “isolation resistance” on the LED screen).

2. What's the start up DC voltage in the manual?

Before the SMA inverter I had another brand which was a pile of ****. The DC start up voltage was over 300V. The SMA starts at around 150V (or about 6W AC per string). In winter mine starts up around sunrise or later and sometimes not until 9:30 or 10 am if it's really gloomy. It also turned off again in the early afternoon last week because it got so dark.

Your system will probably be starting on one string only since you have an East-West split but if it requires only 90V that shouldn't be a problem. Also, some brands of panels are better in low, diffuse light than others.

You won't be losing much production on gloomy days - probably only a couple of kWh per year. But it is depressing when it happens (especially as coincides with the grotty weather).



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