Hi,

Two questions, panel placement, and panel quantity on a 16kv sunsynk.

Wanting some guidance on panel placement so I can start to plan which roof repairs to prioritise before I throw panels up, or whether I can get some panels up before any repair work.

Roof membrane is old on the top floor, so requires replacement (tiles off, battens off, new membrane, replace) - not ready to do that right now given the quotes I've received, so holding off with that.

Sunsynk 16kv, single phase, durban

Attached image shows the suns path currently (March).

Sections of the roof in the image labelled as follows:

1. Top floor roof, good angle, NE facing - definite yes (req roof membrane repairs though)

2. Top floor roof, good angle, SW facing - not sure? (req roof membrane repairs though)

3. Ground floor roof, slightly less angled roof, NE facing - shade starts to spread onto it after 1/130pm as the top floor starts to cast a shadow (no repairs req)

4. Garage roof, good angle, NW facing, shaded in the morning from the top floor shadow (no repairs req)

5. Top floor side portion, NW facing, small area - could link to area 4 on one string else not worth bothering

Looking at putting up 16 panels initially, and then adding another 8 or more thereafter in stages.

Which sections would be worthwhile throwing panels onto and which would be a waste of time?

Would 3 and 4 be feasible initially (given no repairs to roof required) - in terms of direction, shaded times, or bit of a waste?

Or put them up one go on the roof with the bad membrane, and remove when re-doing the roof (hesitant due to damage etc)

Lastly, whats ideal panel choice and quantity for a 16kv sunsynk - looking at JA or Jinko - something easily available,

Should I go for 600w or 550-565w, and quantity per string / per mppt?

Any guidance/input welcome.

Thanks in advance

1,5,4&3, in that order, I'd suggest..

1 hour ago, Kalahari Meerkat said:

1,5,4&3, in that order, I'd suggest..

Agreed - get as many as you can on 1 and 5 and then add additional later if necessary to 4 and 3. South facing gives terrible results, especially in winter, and should be a last resort.

Having installed panels myself a few times, it's not that much extra work to remove them later when redoing the roof. I also need to tackle the membranes in my roof but have also decided to put it off until desperate as it's a massive expense.

@ga_za ,

You need to analyze this a bit more careful. 1st look at the specs of the Inverter.

The ideal & Max PV string Voltage is 425V and Isc = 26 A. So 425V/8-9 panels in string = 47-53 V. So you need to look for a panel that has Voc around 47-53V and Isc = 26A. That does not exists (yet), so that should give you a clue that you need to parallel 2 string from the get go. So Isc = around 13A. Can go a bit higher, to account for losses in cables etc. Even a JA Solar 580 is a bit high on Voc, but as you did not state your location, I would go for something smaller e.g. 545 or 555W, if you reside in a colder part of the country e.g. Gauteng. Freestate Bethlehem etc area I would even go smaller, like 500W or so. (Bigger isn't always better😉). If you reside is a warmer part of the country (no temps below freezing), you may want to go slightly larger in Wattage.

As the Inverter has 3 MPPT's, you can entertain 3 strings. Ideal would be an East, North & West orientation, to "lengthen" the production during the day. As you have very little East facing roof (+ possible shading from the neighbor), I would want to use 2 MPPT's in the northerly direction. That's 4 x 8 x 500-545W on roofs 1 & 3. That will give you healthy production +- (14-15 kW) during midday hours. If you do not have enough space for 32 panels, then go 4 x 7 x 600W config. or 4 x 6 x 600W as a last resort, space dependent.

Lastly, the 3rd MPPT to be used on roofs 4 & 5, which will give you nice production later in the afternoon, so you can start your cooking chores around 4pm in summer (and much earlier in Winter). The assumption is that the whole house is on Essential. I have this setup, and use Airfrier & standard oven for cooking/baking, with gas stove in reserve, as we work from home. Yes, I bake muffins and brownies in the airfrier regularly🤪.

Not all 3 strings need to be the same length.

So you may end with something like this as well:

String 1 : North : Roof 1: 2 x 6 x 600W*

String 2: North : Roof 3#: 2 x 7 x 600W*

String 3: West : Roof 4 & 5: 2 x 5 x 600W*

* substitute 600W with smaller Wattage if in colder area.

#Can be split over Roof 1 as well.

With some clever orientations (portrait & landscape combined), you may just be able to install the full capacity of the Inverter - around 21 kW worth of PV on your available roof space.

Yes ga_za, start with sections 3 and 4 to avoid delay. the minimal shade and no repairs needed. Avoid top floor roofs for now due to membrane issues unless you're fine with later removal.