January 30, 20242 yr Thinking of increasing my solar production has raised the following questions re understanding (Sunsynk/Deye) 2 inputs per MPPT behaviour. Research on powerforum and other searches has only confused me so I wonder if anyone can definitively answer my queries. 1.) If I have 2 strings, 1 going to MPPT1-1 and the other to MPPT1-2 do they have to be equal? i.e. same number and type of panel or close enough specs. 2.) Do these 2 strings have to be in the, more or less, same direction and angle? Or can 1 string face, say, East and the other West? 3.) Do the standard parallel rules apply? For example, if the MPPT PV input current is rated at, say, 22A, does that limit each string to 11A? 4.)What, apart from not having to have a combiner box or paralleling using Y connectors for the 2 strings, is the advantage of having an MPPT with 2 inputs?
January 30, 20242 yr 8 hours ago, Thunderdolt said: Thinking of increasing my solar production has raised the following questions re understanding (Sunsynk/Deye) 2 inputs per MPPT behaviour. Research on powerforum and other searches has only confused me so I wonder if anyone can definitively answer my queries. 1.) If I have 2 strings, 1 going to MPPT1-1 and the other to MPPT1-2 do they have to be equal? i.e. same number and type of panel or close enough specs. 2.) Do these 2 strings have to be in the, more or less, same direction and angle? Or can 1 string face, say, East and the other West? 3.) Do the standard parallel rules apply? For example, if the MPPT PV input current is rated at, say, 22A, does that limit each string to 11A? 4.)What, apart from not having to have a combiner box or paralleling using Y connectors for the 2 strings, is the advantage of having an MPPT with 2 inputs? 1. Same number and close to the same spec to get the same voltage. 2. Different directions is no problem. 3. Can be different currents as they will sum up. 4. Ease of connecting without the hassle of a combiner box BUT you still need the protection so I like the expense of a combiner. Without the combiner changing say 4 + 4 can be changed to 8 in series at the inverter. Just my own thoughts.
January 31, 20242 yr The two strings can have different panels from each other, on the same sting panels should match very closely
January 31, 20242 yr >1.) If I have 2 strings, 1 going to MPPT1-1 and the other to MPPT1-2 do they have to be equal? i.e. same number and type of panel or close enough specs. The MPPT are independent so can be different. Just ensure you are within the ranges of the MTTT in terms of max/min voltage & amps. > 2.) Do these 2 strings have to be in the, more or less, same direction and angle? Or can 1 string face, say, East and the other West? East & West is fine and often better than just North Not sure for 3 & 4
January 31, 20242 yr On 2024/01/30 at 2:36 PM, Thunderdolt said: Thinking of increasing my solar production has raised the following questions re understanding (Sunsynk/Deye) 2 inputs per MPPT behaviour. Research on powerforum and other searches has only confused me so I wonder if anyone can definitively answer my queries. 1.) If I have 2 strings, 1 going to MPPT1-1 and the other to MPPT1-2 do they have to be equal? i.e. same number and type of panel or close enough specs. 2.) Do these 2 strings have to be in the, more or less, same direction and angle? Or can 1 string face, say, East and the other West? 3.) Do the standard parallel rules apply? For example, if the MPPT PV input current is rated at, say, 22A, does that limit each string to 11A? 4.)What, apart from not having to have a combiner box or paralleling using Y connectors for the 2 strings, is the advantage of having an MPPT with 2 inputs? Assuming we're talking about either a 5kW or 8kW Deye with 2 MPPT inputs, each MPPT with a positive and negative terminal, either 13A input per MPPT on the 5kW, or otherwise around 22A input on each MPPT for the 8kW. Different setup on the 12kW 3-phase with 26A+13A inputs, we're not talking about that here now. 1. As above, MPPT1 and MPPT2 operate independently of each other. Strings can be totally different if connected each to his own MPPT input. 2. Strings on MPPT1 and MPPT2 can face in different directions if needed, eg all panels on MPPT1 facing East, all panels on MPPT2 facing West, that's no problem at all. 3. The limit of 22A on the MPPT1 and MPPT2 of the 8kW Deye is the limit PER MPPT (22A+22A). You can happily put two strings of 11A in parallel combined onto MPPT1, and you can do the same again on MPPT2. You can even put higher-amp panels like a string of 13A in parallel on MPPT1 or MPPT2, and the normal parallel rules will apply, but then the MPPT will start clipping the current at higher levels of power as you reach 22A. 4. Greater flexibility, greater power generation with complex roof shapes. Better than trying to put East and West-facing panels on the same MPPT because of different currents through the panels at different times of the day. I know that it gets done and folks say they get acceptable results throughout mid-day using East-West panels in parallel on the same MPPT, specially if the roof is a bit flatter, but one direction per MPPT is simpler, cleaner. Edited January 31, 20242 yr by GreenFields
February 1, 20242 yr Author On 2024/01/31 at 4:26 AM, Virwat said: You mean like this? YES. That's why I refereed to 1-1 and 1-2. I thought that would be clear that I was querying about ONE of the 2 MPPTs. 18 hours ago, GreenFields said: You can happily put two strings of 11A in parallel combined onto MPPT1 As I said, previous searches were confusing on this query and as some of the above replies indicate why! 18 hours ago, GreenFields said: 4. Greater flexibility, greater power generation with complex roof shapes Thanks @GreenFields once again for educating me.
February 1, 20242 yr That's why I put that pic and question so others know exactly what you mean. Sorry for my stupid help!
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