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Is 10x 460w solar panels too many for 5kw inverter/battery?


Praemon

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Hi all,

So I have a Sunsynk 5kw + Hubble 5kw battery system and looking to add solar panels. An installer has quoted me for 10x 460w panels (4x North-West at 30 degree angle, and 6x flat on garage roof facing North-East at a 5 degree angle). There's going to be some extra loss due to the flat laying panels (but decent coverage most of the day), however, my main concern is that I will be over sizing what I can actually consume. I use about 550kWh a month (so around 15 - 20kWh a day), and it's split between essential (mainly aircons and heaters) and non-essential (solar geyser, stove, tumble dryer, etc). I don't plan on adding another battery anytime soon. Since my usage is fairly low, do you think I'm adding too many panels and will lead to excess wasted energy due to the limited battery capacity (ie. I can only consume so much while the panels produce energy, and the battery can only last a few hours when there's no production)?

Thanks.

Edited by Praemon
Correcting directions of facing panels
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I wouldn't call it "wasted" energy but rather non-utilised 🙂 

It is also worthwhile bearing in mind that whilst you may have loads of "non-utilised" energy on sunny days in summer. You will be less likely to run out of solar power on overcast days and in the winter months especially from your flat roof due to the sun travelling much closer to the horizon in winter. 

The Sunsynk 5kw will use up to 6500W of DC power. It is however not uncommon to oversizing the panels to >7500W to ensure sufficient production on those lower solar radiation days. 

Main thing is to move as many of your non-time sensitive loads to during the day. e.g. Geyser heating etc

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2 hours ago, Praemon said:

Hi all,

So I have a Sunsynk 5kw + Hubble 5kw battery system and looking to add solar panels. An installer has quoted me for 10x 460w panels (4x North-East at 30 degree angle, and 6x flat on garage roof facing East). There's going to be some extra loss due to the flat laying panels (but decent coverage most of the day), however, my main concern is that I will be over sizing what I can actually consume. I use about 550kWh a month (so around 15 - 20kWh a day), and it's split between essential (mainly aircons and heaters) and non-essential (solar geyser, stove, tumble dryer, etc). I don't plan on adding another battery anytime soon. Since my usage is fairly low, do you think I'm adding too many panels and will lead to excess wasted energy due to the limited battery capacity (ie. I can only consume so much while the panels produce energy, and the battery can only last a few hours when there's no production)?

Thanks.

I definitely don't think its too many panels.  Having an east / west split reduces your total production by 10-20%.  I have 12x540w (east west), and on cloudy days my 1x hubble 5.5kw doesn't fully charge (when other loads are being used). 

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Always remember though to ensure your strings are below the max DC Voltage for the Inverter. An excess of Amps will be clipped, too high a Voltage will burn your MPPT.
I oversized my panels too and it was worth the while as even on cloudy days I still get decent yields. 

Edited by zsde
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9 minutes ago, Scorp007 said:

The 6 on the garage roof laying flat. Is that a flat roof or what is the angle?

Do you intent using both MPPTs or only 1?

It's 5 degrees facing North-East. The others are North-West (I incorrectly stated in my original post the directions). I'm not sure what the intent is from the installer for the MPPTs, but I'm assuming using both (1 string on each MPPT)?

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4 hours ago, Praemon said:

It's 5 degrees facing North-East. The others are North-West (I incorrectly stated in my original post the directions). I'm not sure what the intent is from the installer for the MPPTs, but I'm assuming using both (1 string on each MPPT)?

Just ensure he uses both and not all of them in 1 series string. Having said that a string of 4 is cutting it fine for the MPPT to start.

Edited by Scorp007
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  • 5 months later...

Hi, forgive me but I have a linked question.  I too have the SunSunk 5KW inverter (about to be installed).  Some installers quote 550KW, others max 460KW size panels.  What is the largest size panel which can be used with this inverter which will not violate the warranty / cause other challenges.  I am not technical, I simply want to ensure I buy the right size panels upfront?  Appreciate any guidance.  Thank you, Clinton

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1 hour ago, Clinton DCB said:

Hi, forgive me but I have a linked question.  I too have the SunSunk 5KW inverter (about to be installed).  Some installers quote 550KW, others max 460KW size panels.  What is the largest size panel which can be used with this inverter which will not violate the warranty / cause other challenges.  I am not technical, I simply want to ensure I buy the right size panels upfront?  Appreciate any guidance.  Thank you, Clinton

It's difficult to answer without knowing the current and VOC of the panels in question. If you exceed the MPPT current then the inverter will clip / limit to the max.

However if you exceed the voltage on the MPPT then it will blow and no warranty will fix that

So you always size the string on an MPPT to be below voltage and near max current for best performance. 

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17 hours ago, Clinton DCB said:

Hi, forgive me but I have a linked question.  I too have the SunSunk 5KW inverter (about to be installed).  Some installers quote 550KW, others max 460KW size panels.  What is the largest size panel which can be used with this inverter which will not violate the warranty / cause other challenges.  I am not technical, I simply want to ensure I buy the right size panels upfront?  Appreciate any guidance.  Thank you, Clinton

550W panels are normally around 49V and 13A. Max PV Watts for a 5K SS is 6500W

I like bigger better. I would do 14x 550W on 2 strings of 7. That would be 7700W on a full sun day and the inverter might limit you a bit but in winter/overcast days you'll be happier

Edited by Chris_S
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