This is a diagram of what our ten panel will look like on the roof. The four panels on the right in blue are shaded till about 9.30am by the neighbours house. The sun moves right to left so panels 4 and 9 will clear first and then 5 and 10. The orange line shows shading from the chimney in the early evening (6.30pm at the moment). Note we will be installing Tigo optimisers on all panels.
So how best to wire them? The inverter we're getting is a Givenergy 3.6 Gen2. This has a start up voltage of 150v and an MPPT range also starting at 150v. The solar panels have a voltage at maximum output of 38.6v. I think there are the following options:
1 - Put panels 4, 5, 9 and 10 on one MPPT and the other six on another MPPT. This means that six of the panels can start generating quickly and the other four (4, 5, 9 and 10) will come on stream when they are all clear of shade. BUT - 4 x 38.6v = 154.4v. This is only JUST in the usable range for the inverter - it feels a bit too tight for me.
2 - Put two equal rows of five on each MPPT - so 1, 2, 3, 4, and 5 on one MPPT and 6, 7, 8 , 9 and 10 on the other MPPT. But this means that although 1, 2, 3, 6, 7 and 8 have enough voltage to start the inverter, there isn't enough for each MPPT and won't be until the remaining panels are clear of shade. This looks like the worst option to me.
3 - As per option 1 - put 4, 5, 9 and 10 on one MPPT but also an additional panel, 3, on one MPPT and the others on the other MPPT. This at least means that five (1, 2, 6, 7 and 8) will start generating quickly and there will be a comfortable voltage on both MPPTs (5x38.6 = 193v). This configuration might also help later in the day given the way the shade from the chimney falls as 3, 4, 5, 9 and 10 are the least affected.
4 - Put all ten on one MPPT. Without Tigos this would be a non-starter but even with Tigos, still not sure it' the way to go.
The main issue here is the high startup voltage of the GivEnergy inverter. I know there are other inverters with a significantly lower voltage requirements but difficult finding an installer to who you can say "I want THIS inverter, THIS battery, THESE panels"
Any advice greatly welcome ahead of a site visit from installer.
So how best to wire them? The inverter we're getting is a Givenergy 3.6 Gen2. This has a start up voltage of 150v and an MPPT range also starting at 150v. The solar panels have a voltage at maximum output of 38.6v. I think there are the following options:
1 - Put panels 4, 5, 9 and 10 on one MPPT and the other six on another MPPT. This means that six of the panels can start generating quickly and the other four (4, 5, 9 and 10) will come on stream when they are all clear of shade. BUT - 4 x 38.6v = 154.4v. This is only JUST in the usable range for the inverter - it feels a bit too tight for me.
2 - Put two equal rows of five on each MPPT - so 1, 2, 3, 4, and 5 on one MPPT and 6, 7, 8 , 9 and 10 on the other MPPT. But this means that although 1, 2, 3, 6, 7 and 8 have enough voltage to start the inverter, there isn't enough for each MPPT and won't be until the remaining panels are clear of shade. This looks like the worst option to me.
3 - As per option 1 - put 4, 5, 9 and 10 on one MPPT but also an additional panel, 3, on one MPPT and the others on the other MPPT. This at least means that five (1, 2, 6, 7 and 8) will start generating quickly and there will be a comfortable voltage on both MPPTs (5x38.6 = 193v). This configuration might also help later in the day given the way the shade from the chimney falls as 3, 4, 5, 9 and 10 are the least affected.
4 - Put all ten on one MPPT. Without Tigos this would be a non-starter but even with Tigos, still not sure it' the way to go.
The main issue here is the high startup voltage of the GivEnergy inverter. I know there are other inverters with a significantly lower voltage requirements but difficult finding an installer to who you can say "I want THIS inverter, THIS battery, THESE panels"
Any advice greatly welcome ahead of a site visit from installer.
