GrootBaas' Solar

Katelknaap said:
8 x 605W Canadians on a 5kw Sunsynk? My installer refused to go any larger than 460W Ja Solar's on mine. Indicated that the amps on the larger panels runs the risk of damaging the inverter when the circumstances are just right (or wrong, however you want to look at it).
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I think your installer is just been conservative. Yes, I am pushing the limits under ideal lab conditions. In hindsight the 8kw sunsynk would have been a better buy.
 
DX'er said:
I think your installer is just been conservative. Yes, I am pushing the limits under ideal lab conditions. In hindsight the 8kw sunsynk would have been a better buy.
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Might be, I don't have the technical knowledge to argue the point with him (or anyone for that matter). Since he's a qualified electrical engineer, I heed his advice and follow his guidance. Each to his own though, hopefully everything just works and there is never any issues.
 
Katelknaap said:
Might be, I don't have the technical knowledge to argue the point with him (or anyone for that matter). Since he's a qualified electrical engineer, I heed his advice and follow his guidance. Each to his own though, hopefully everything just works and there is never any issues.
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They don't teach this stuff though, the program is focused more on principles and design. The little bit of lab work focuses more on practical applications of concepts. No engineering program teaches you about the limitations of an MPPT charge controller. A lot of the learnings come from (lots of) real world experience.

As an engineering graduate myself I'll be the first to admit to being pretty clueless on a lot of this when I first started out. But I would rather admit to being wrong if it means others can learn from it...
 
DX'er said:
If I recall Hiku7 mono 605 Watt. Current at midday according to solar assistant just under 13A. So on the limits as indicated.
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Cool. What is more or less your approximate location, for minimum temperature calcs?
 
DX'er said:
If I recall Hiku7 mono 605 Watt. Current at midday according to solar assistant just under 13A. So on the limits as indicated.
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This CS panel's voltage is relatively low, so assuming that your lowest temperature in your area is -1 degrees C, you could easily place 9 (414.28v) or even 10 (460.31V) in series without blowing the MPPT, which tops out at 500V. The optimal sweet spot for the MPPT is under 425V though, so 9 would be better.

If I look at the data sheet, it states that Isc is 18.52A at STC, and Imp 17.25A.
1692817865162.png

NMOT for the panel is 41 degrees C (give or take 3 degrees either way), with an ambient temperature of 20 degrees.
1692819377855.png

I was still a little concerned about the high Isc at STC though, so I did some calcs. At midday, ambient temperature may be 33 degrees C, which will probably throw the NMOT current calculation out by a factor of 0.05 percent per degree. Amps, unlike voltage, rise with temperature, so your panel string in series (and under load) could be producing up to 13.889 amps, which the MPPT will reduce to just under 13A, so not too much wasted. It would perform like a 585 W panel. I hope that it survives the summer, keep us posted.
 
RonSwanson said:
This CS panel's voltage is relatively low, so assuming that your lowest temperature in your area is -1 degrees C, you could easily place 9 (414.28v) or even 10 (460.31V) in series without blowing the MPPT, which tops out at 500V. The optimal sweet spot for the MPPT is under 425V though, so 9 would be better.

If I look at the data sheet, it states that Isc is 18.52A at STC, and Imp 17.25A.
View attachment 1575930

NMOT for the panel is 41 degrees C (give or take 3 degrees either way), with an ambient temperature of 20 degrees.
View attachment 1575948

I was still a little concerned about the high Isc at STC though, so I did some calcs. At midday, ambient temperature may be 33 degrees C, which will probably throw the NMOT current calculation out by a factor of 0.05 percent per degree. Amps, unlike voltage, rise with temperature, so your panel string in series (and under load) could be producing up to 13.889 amps, which the MPPT will reduce to just under 13A, so not too much wasted. It would perform like a 585 W panel. I hope that it survives the summer, keep us posted.
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Thanks for the info. The 8kW inverter would have been the correct choice. I did a lot of research in the beginning, however I must admit that I overlooked the current limitations of the MPPT of the 5kW unit.
My current task is to add a cooling fan to the inverter, as running at close to 13A greates lots of heat. Will use a simple PTC circuit to put the fan on at around 35 to 40 degrees C. Will keep you posted.
 
DX'er said:
Thanks for the info. The 8kW inverter would have been the correct choice. I did a lot of research in the beginning, however I must admit that I overlooked the current limitations of the MPPT of the 5kW unit.
My current task is to add a cooling fan to the inverter, as running at close to 13A greates lots of heat. Will use a simple PTC circuit to put the fan on at around 35 to 40 degrees C. Will keep you posted.
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There is fokol wrong with the 5K, unless you have a very large family. I have one myself. If you do decide to swop it out, go with the Solis 8K, it's a far better machine, more capable and the service and support is streets better, even though it's cheaper than the 8K Sunsynk.
There's a healthy second hand market for that 5K Sunsynk, so while you won't get your money back, you will definitely not struggle to sell provided that you price it right.
 
RonSwanson said:
AThere is fokol wrong with the 5K, unless you have a very large family. I have one myself. If you do decide to swop it out, go with the Solis 8K, it's a far better machine, more capable and the service and support is streets better, even though it's cheaper than the 8K Sunsynk.
There's a healthy second hand market for that 5K Sunsynk, so while you won't get your money back, you will definitely not struggle to sell provided that you price it right
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A update. Added two 80mm sqmm fans underneath the inverter heat sinks. Attached a sensor to the side of the heat sink which is controlled by a R72.00 temp controller. Fans set to switch on at 35 degrees C. Image taken this morning of the inverter temp going down after installing the temp controller. On the left is yesterday's inverter temp just over 60 egress C. Onthe right this mornings temp going down.


I will look at the Solis 8k, but we don't use more than 12kWh per day on essentials.thanks to Al for their inputScreenshot_20230828-110319.jpg
 
DX'er said:
A update. Added two 80mm sqmm fans underneath the inverter heat sinks. Attached a sensor to the side of the heat sink which is controlled by a R72.00 temp controller. Fans set to switch on at 35 degrees C. Image taken this morning of the inverter temp going down after installing the temp controller. On the left is yesterday's inverter temp just over 60 egress C. Onthe right this mornings temp going down.
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That's the temp problem sorted, it will last far longer now.
DX'er said:
I will look at the Solis 8k, but we don't use more than 12kWh per day on essentials.thanks to Al for their input
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Same as mine, so then the 5K should be more than sufficient. You will probably just need to make some minor lifestyle changes, like getting a whistling kettle for the gas stove so that you can make toast, airfry bacon and wash clothes at the same time.
 
RonSwanson said:
That's the temp problem sorted, it will last far longer now.

Same as mine, so then the 5K should be more than sufficient. You will probably just need to make some minor lifestyle changes, like getting a whistling kettle for the gas stove so that you can make toast, airfry bacon and wash clothes at the same time.
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A updated image showing tempScreenshot_20230828-134436.jpg
 
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