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Author Topic: Inverter for 6600w of panels  (Read 2879 times)
Solarchaser
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« on: May 23, 2019, 06:13:33 PM »

Hello all, around 6 months ago I bought a growatt sph3600.
Its spec said it can cope with 6600w of panels, so that's what I fitted to my garage roof on an e/w (ish) orientation.

I already had 4kw on the house roof and a sofar me3000sp with 6kw of batteries, so it made sense to rewire the garage feed to be seen as solar input, and the hope was that the sph and sofar would work together, but it didnt really work... well it worked about 70% of the time.

I've had various issues with the growatt,  not least the fact it has been putting out 5800w at times,  not ideal for the 2.5t&e that I have going to the isolator... because its supposed to max out at 3600w.

So anyway growatt are finally going to refund me, but it leaves me with a bit of a question of what to replace it with.

There doesnt seem to be any other 3.6kw inverters that will take 6600w, and I want to make the most of the solar power.

So my first question is does anyone know of a reliable inverter that will cope with 6600w (3300/string) that wont break the bank, or perhaps a couple of 3kw inverters instead.

I'm hoping to pick the inverters up cheap second hand, as I'm aiming to spend the refund on parallelable lux ac inverters and batteries replacing the sofar, which I'll sell on.... (though there is also a chance it will get spent on a thermal store), so I've been watching fleabay for a couple of weeks, but I'm not really that sure what makes to avoid.

Has anyone had a particularly good or bad experience with inverters?
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Tinbum
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« Reply #1 on: May 23, 2019, 06:22:03 PM »

I run an SMA 4000 TL with 8kW of panels on it with no problems. It will often just sit there at its max 4000w output. The panels are facing East but on a shallow pitch and go through a Growatt SP2000 first.

Its finding an inverter that will cope with 100% duty cycle at 100% load.
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85no 58mm solar thermal tubes, 28.5Kw PV, 3 x Sunny Backup 5048, 3x Sunny Island 5048, 2795 Ah (135kWh) (c20) Rolls batteries 48v, Atmos wood gasification boiler, Brosley wood burner, 2000lt buffer tank and 250lt DHW
Solarchaser
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« Reply #2 on: May 23, 2019, 06:56:28 PM »

The 4000tl says it will only take 4200w, so I'm stunned you get away with 8kw of panels.

Great to know the SMA inverters are happy with heavy loading though, thanks genuflect
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RIT
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« Reply #3 on: May 23, 2019, 09:17:39 PM »

The 4000tl says it will only take 4200w, so I'm stunned you get away with 8kw of panels.

Great to know the SMA inverters are happy with heavy loading though, thanks genuflect

Their old models seem to have been quoted with max inputs very near their max output, but if you look at the spec sheets of their newer products you will see that the range has been greatly increased. Regardless of the model the imbalance is handled by the MPPT module that can vary the resulting input from the panels via changing the input voltage.

The latest Sunny Boy 4.0, 5.0 and 6.0 all listed as accepting inputs higher than 6600w.


To use 2 inverters from SMA, while limiting their combined output due to cabling or DNO limits you need to look at installing a Sunny home manager and SMA Energy Meter, these, when combined with 2 (or more) inverters, allow the peak output from the inverters to be managed.
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2.4kW PV system, output can be seen at  - https://pvoutput.org/list.jsp?userid=49083

Why bother? - well, there is no planet B
andrewellis
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« Reply #4 on: May 24, 2019, 09:14:45 AM »

Another solution is the solar edge he wave line. You can use up to 6kw in the house depending on inverter but will limit export to whatever you set. The only caveat is I am not sure whether you need the power optimisers for full management.
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6.48kw Solar PV JA (300W)Panels, SolarEdge inverter
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Tinbum
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« Reply #5 on: May 24, 2019, 09:40:29 AM »

The 4000tl says it will only take 4200w, so I'm stunned you get away with 8kw of panels.

Great to know the SMA inverters are happy with heavy loading though, thanks genuflect
It seems to cope fine and no undue heat.



(edit- of course you can set the inverters max output in the software- so it would be a little like having 4kW of panels on this inverter but setting its output at say 1kW)
« Last Edit: May 24, 2019, 09:45:38 AM by Tinbum » Logged

85no 58mm solar thermal tubes, 28.5Kw PV, 3 x Sunny Backup 5048, 3x Sunny Island 5048, 2795 Ah (135kWh) (c20) Rolls batteries 48v, Atmos wood gasification boiler, Brosley wood burner, 2000lt buffer tank and 250lt DHW
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