April 28, 20233 yr Just want to make sure I'll be OK. Been running a 8kw sunsynk and 8x JA 550W panels on 1 mppt for a couple of months. I'm going to be adding more panels on the other mppt soon. Took delivery today of 12x Canadian solar 455W panels model CS6L-455MS for a 6S2P configuration due to roof size and orientation. My concern is that this model has a lower voltage STC Vmp 34.6V Imp 13.17A NMOT Vmp 32.4V Imp 10.52A This is going to give me about 200V on the mppt. Is this not really ideal? Will I lose efficiency? I don't want to put more panels per string.
April 28, 20233 yr 45 minutes ago, Chris_S said: Just want to make sure I'll be OK. Been running a 8kw sunsynk and 8x JA 550W panels on 1 mppt for a couple of months. I'm going to be adding more panels on the other mppt soon. Took delivery today of 12x Canadian solar 455W panels model CS6L-455MS for a 6S2P configuration due to roof size and orientation. My concern is that this model has a lower voltage STC Vmp 34.6V Imp 13.17A NMOT Vmp 32.4V Imp 10.52A This is going to give me about 200V on the mppt. Is this not really ideal? Will I lose efficiency? I don't want to put more panels per string. New string is perfect. 2nd MPPT will start early at the 200V. No problem not using higher voltage panels.
April 29, 20233 yr Author 16 hours ago, Scorp007 said: New string is perfect. 2nd MPPT will start early at the 200V. No problem not using higher voltage panels. Thanks. It's just that I've seen comments about getting mppt's on sunsynks above 300V for better efficiency. You sure 200V will be good?
April 29, 20233 yr 15 minutes ago, Chris_S said: Thanks. It's just that I've seen comments about getting mppt's on sunsynks above 300V for better efficiency. You sure 200V will be good? The closer you get to 370V the better . I started with 5 panels on a string and then later upgrades to 8 on a string and saw a noticeable increase in production per panel. The 5 Panels was running at about 200V and the 8 panels run at about 300V. Will it work at 200V just fine ? yes .
April 29, 20233 yr Author 16 minutes ago, Nexuss said: The closer you get to 370V the better . I started with 5 panels on a string and then later upgrades to 8 on a string and saw a noticeable increase in production per panel. The 5 Panels was running at about 200V and the 8 panels run at about 300V. Will it work at 200V just fine ? yes . How much per panel increase did you notice when using 8 panels?
April 29, 20233 yr 22 minutes ago, Chris_S said: How much per panel increase did you notice when using 8 panels? 30W+- up to 40W sometimes.
April 29, 20233 yr 7 hours ago, Chris_S said: Thanks. It's just that I've seen comments about getting mppt's on sunsynks above 300V for better efficiency. You sure 200V will be good? I cannot talk about efficiency on a Sunsynk. My Solis has a Voc max of 600V and a 50-500V MPPT range. From the day I switched on with 2 panels and then to 3 and to 5 and to 6 I did not see any gain. Each time my daily yield per panel worked out the same. Panels are working flat out and not affected by load or battery state. To add another thing. Even after adding poly to my mono string no change. I am running 4 makes in my 6S string. 6S string is running at 170-220V. I would not be bothered getting 40W less on a string of 8 panels. That is just me 😀 Edited April 29, 20233 yr by Scorp007
April 29, 20233 yr 40 minutes ago, Scorp007 said: I would not be bothered getting 40W less on a string of 8 panels. That is just me Thats per panel .. not per string. In my mind its quite a big gain .
April 29, 20233 yr 29 minutes ago, Nexuss said: Thats per panel .. not per string. In my mind its quite a big gain . Yes that does seem a good gain then......
May 30, 20233 yr Author On 2023/04/28 at 4:44 PM, Chris_S said: Just want to make sure I'll be OK. Been running a 8kw sunsynk and 8x JA 550W panels on 1 mppt for a couple of months. I'm going to be adding more panels on the other mppt soon. Took delivery today of 12x Canadian solar 455W panels model CS6L-455MS for a 6S2P configuration due to roof size and orientation. My concern is that this model has a lower voltage STC Vmp 34.6V Imp 13.17A NMOT Vmp 32.4V Imp 10.52A This is going to give me about 200V on the mppt. Is this not really ideal? Will I lose efficiency? I don't want to put more panels per string. What do you guys think about the amps on the panels on a sunsynk 8kw inverter? Max mppt amps 28 A 6S2P is going to give me 26A in ideal conditions and will be clipped in that case. I'm not concerned as one string is SE direction and 1 string is west. So midday sun will hit panels at angles so max amps shouldn't be seen. My concern is going over 28A during cloud Edge. I've seen my 550W panels go to 15A for brief moments. That's a possible 30A on one mppt with 455W 6S2P.
May 30, 20233 yr 8 hours ago, Chris_S said: What do you guys think about the amps on the panels on a sunsynk 8kw inverter? Max mppt amps 28 A 6S2P is going to give me 26A in ideal conditions and will be clipped in that case. I'm not concerned as one string is SE direction and 1 string is west. So midday sun will hit panels at angles so max amps shouldn't be seen. My concern is going over 28A during cloud Edge. I've seen my 550W panels go to 15A for brief moments. That's a possible 30A on one mppt with 455W 6S2P. Why would you risk the inverter knowing you will exceed the all time maximum rating of the MPPTs? I belief it is provided for a reason.
May 30, 20233 yr Author 18 minutes ago, Scorp007 said: Why would you risk the inverter knowing you will exceed the all time maximum rating of the MPPTs? I belief it is provided for a reason. The 450W panels I wanted were 49V 10A. I got a call from supplier saying they got 455W Canadians in stock. You know how the situation is now so I rushed there and took delivery. I looked at the panels the next day and they are 40V 13A. In this case I might as well have gone for 550W panels that are also 13A. But I wanted 450W for this very reason of doing 2 parallel strings. Now that they are 13A I have this problem. Doubt it I can return them all. It's a tricky one so I'm asking. Is there anyone that are running 550W panels in parallel on a sunsynk 8kw?
June 1, 20233 yr Author Still need assistance. I've been through the manual again. They state max Isc is 28A. I take it that's short circuit. My panels Isc is 13.97A So I'll be at 28A or just under with 6S2P. But during cloud Edge I could go over 28A. Will it be clipped over 28A as its not short circuit? Manual only states to be careful of max Voc. Another consideration is with this 6S2P on one mppt and my 8S on the other mppt my max panel Watts will be 9800 but with the inverter set at 9000 it shouldn't run all the panels at max amps right? Edited June 1, 20233 yr by Chris_S
June 2, 20233 yr 16 hours ago, Chris_S said: Still need assistance. I've been through the manual again. They state max Isc is 28A. I take it that's short circuit. My panels Isc is 13.97A So I'll be at 28A or just under with 6S2P. But during cloud Edge I could go over 28A. Will it be clipped over 28A as its not short circuit? Manual only states to be careful of max Voc. Another consideration is with this 6S2P on one mppt and my 8S on the other mppt my max panel Watts will be 9800 but with the inverter set at 9000 it shouldn't run all the panels at max amps right? You want to be careful of exceeding max Voc as that will kill the inverter circuitry (I think 460V is the absolute max as the sunsynk dude on youtube said in one of his videos, might have been 425V, don't remember exactly), however over-amps will simply be clipped and should not harm the inverter. In fact many people buy more solar than what the inverter can handle and the extra current simple gets clipped in summer, but then in winter you will have good power output from your panels.
June 3, 20233 yr Author @Steve87do you mind looking through this thread. Maybe I can pm you if OK? I'm sitting with these panels and want to see what I should do before trying to return them. Quick summary. 6S2P string. Vmp = 207.6V Imp = 26.34A Sunsynk 8kw I 22A Max 28A South East and west orientation so the chances of hit max amps on both strings is the question. I expect it to clip at 22A but concerned about that 28A max during cloud Edge.
June 3, 20233 yr Personally I think you're overthinking it and you're well within limits. Cloud Edge is rare and often momentary so that's hardly a concern
June 3, 20233 yr Author 15 minutes ago, madness_za said: Personally I think you're overthinking it and you're well within limits. Cloud Edge is rare and often momentary so that's hardly a concern Thanks. I tend to agree with you
June 3, 20233 yr Author 8 minutes ago, Superfly said: Strictly speaking you should stick within the PV short circuit current max... I have no idea how cloud edge affects it or how much additional amperage is gained or for how long a period but from this... ( I know it's not Sunsynk specific, but generally speaking) https://www.victronenergy.com/upload/documents/Datasheet-SmartSolar-charge-controller-MPPT-250-70-up-to-250-100-VE.Can-EN.pdf 2) A PV array with a higher short circuit current may damage the controller. Thanks. Isc on the array will be 27.88A and mppt max 28A. Cutting it close but it's still under.
June 3, 20233 yr Just hit within the MPPT range which you are within. Dont stress about amps, the MPPT will control that. However, consider that you will have losses. Especially if the Imp is let's say 28A & the max of the inverter is 25A. Then you loosing some power. Don't over think it. Just stick to the basics.
June 3, 20233 yr I stand to correction, but isn't it better to use the NMOT values since the STC values are unlikely to be achieved in real life situations? Edit... Actually I guess for sizing the VoC STC rate should be the decider. Edited June 3, 20233 yr by Thunderdolt Stupid comment
June 3, 20233 yr Author 57 minutes ago, Steve87 said: Just hit within the MPPT range which you are within. Dont stress about amps, the MPPT will control that. However, consider that you will have losses. Especially if the Imp is let's say 28A & the max of the inverter is 25A. Then you loosing some power. Don't over think it. Just stick to the basics. Appreciate your advice again Steve. Thank you.
June 3, 20233 yr 58 minutes ago, Thunderdolt said: I stand to correction, but isn't it better to use the NMOT values since the STC values are unlikely to be achieved in real life situations? The standard test condition for a photovoltaic solar panel or module is defined as being 1000 W/m2 (1 kW/m2) of full solar noon sunshine (irradiance) when the panel and cells are at a standard ambient temperature of 25oC with a sea level air mass (AM) of 1.5 (1 sun). I'm also open to correction. I think you'd have to check the peak hourly solar irradiance data for your location (which I cannot quote precisely), but some areas in SA could get very close to STC if not higher in summer. Some searching for Cape Town indicates that at noon in Dec/Jan some days are upwards of 950W/m^2 up to 980W/m^2. My bet is that for a couple of towns up the West Coast STC is very much everyday "real life." In any case, NOCT is not our normal in SA in summer. In Cape Town, 800w/m^2 is more like a sunny Winter day in August.
June 3, 20233 yr I currently have 12x Canadian 415W panels set as 6S2P, onto the one string of my 8.8 kW SunSynk. My aim is to go to 9S2P on both strings. My firmware hasn't been upgraded for about 2 years now, so the Current is limited to 20A. No problems at all in all seasons. Panels are NW, and 22 degrees, KZN.
June 3, 20233 yr 3 hours ago, Thunderdolt said: I stand to correction, but isn't it better to use the NMOT values since the STC values are unlikely to be achieved in real life situations? Edit... Actually I guess for sizing the VoC STC rate should be the decider. The value of NMOT is that that level should be achieved in summer in full sun. Also in winter if the angle is over about 35 degrees. If this level is used we will not get so many questions about the bad performance of our panels. As @GreenFields indicated earlier NMOT can easily be exceeded in a large area in SA. In haven't been that lucky to exceed STC unless during cloud edge. Based on my recordings cloud edge hardly if ever lasts more than 5 min. It is thus a value not to be used to create an expectation of output during the peak hours.
June 3, 20233 yr Author 3 hours ago, TimCam said: I currently have 12x Canadian 415W panels set as 6S2P, onto the one string of my 8.8 kW SunSynk. My aim is to go to 9S2P on both strings. My firmware hasn't been upgraded for about 2 years now, so the Current is limited to 20A. No problems at all in all seasons. Panels are NW, and 22 degrees, KZN. Hi Tim. Do you know the voltage and amps of your panels?
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.