I had a brainwave. I need your opinion. I have 18 x 550watt solar panels installed on my roof. 9 north and 9 west. My 8kw Sunsynk only have 2 mppt's. So I cannot add a third string on the east side of my house. But what if I install 6 x 620 watt panels on the east side, connect it to some sort of device that only allows one side to be used at a time. So let's say from 06H00 to 10H00 the device or switch cuts off the west side completely and only draw from the east side and then after 10h00 isolate the east side completely and only draws from the west side until 17H00. The device must switch over automatically with say a 1 minute delay before the west start giving electricity to the mppt. Can something like this work

@FransSmith , you should be able to parallel up the same amount and type of panels, that you have to the west, to the east, mid day, it would be capable of supplying more power than the inverter would be able to use, but since the inverter controlls the current flow, this should not really be an issue. Thus, in the morning the east facing panels on that parallel setup would provide 90+% of the power and in the evening the west facing panels would be providing the power...

Your other option would be to add a MPPT solar battery charge module, to the east facing panels and feed the battery/ies directly from this and if the inverter needs power that its panels can't supply, during the earlier morning, then it can take power from the battery/ies, effectively from the east facing panels...

You never see 100% of the rated output from panels

In full sun at noon you will get close to 90% but outside those hours, the output drops substantially

The graph is an example. Partial cloud in Cape Town in early May

You currently have 9 550 on both strings. IE 4950 W.

I've just had a panel upgrade. I have limited North facing roof. I had two strings (N & E) of 6*325.

What I changed to was 5*585 facing N, and moving most of the old panels to beef up the E string. So E is now 10*325. I sold the left over panels.

So depending on how much space you have maybe replace one string with new panels and then numerically boost the other.

I've thought about having a timer that switches off an E string and switches on a W string. But
1) This is DC, so arcing is a very real possibility, so you can't use any old switch.
2) The E facing string produces useful PV until 14:30 or so (and was before the upgrade). I also see the N string coming online quite early in the morning. So panels can react to sunlight from quite a wide angle.

Find out how the Sunsynk works. This may affect your decision. My inverter (Goodwe) prioritises the string with the highest voltage. So when the demand is low in the afternoon it pulls from the E string rather than the N string, because E has more panels in series thus higher voltage. I don't know if this makes a practical difference because it will use both strings when demand is high, but if you are trying to optimise for optimal optimisation then this may be a consideration.

Edited May 10, 20251 yr by Bobster.
Correct panel rating.

4 hours ago, FransSmith said:

Can something like this work

4 hours ago, FransSmith said:

But what if I install 6 x 620 watt panels

Technically time switch sharing could work but not optimally and risks of voiding your Sunsynk warranty.

4 hours ago, Kalahari Meerkat said:

Your other option would be to add a MPPT solar battery charge module, to the east facing panels and feed the battery/ies directly from this and if the inverter needs power that its panels can't supply, during the earlier morning, then it can take power from the battery/ies, effectively from the east facing panels...

Much better idea. Victron 150/85 mppt charge controller comes to mind especially if you want to use higher wattage solar panels as example 6 x 620w then 2S3P would work magic on the east side.

Maybe a bit much, but I were deciding this from scratch and if space allows, I'd go with East-West panel configuration on the Sunsynk's MPPTs, with a 6S2P string of the 550W panels on each.

Then if you really want more power on top, consider the 6x390 panels on a micro-inverter or string inverter, facing North.

11 hours ago, GreenFields said:

Then if you really want more power on top, consider the 6x390 panels on a micro-inverter or string inverter, facing North.

A micro inverter on the Aux port makes sense.

On 2025/05/10 at 10:15 AM, FransSmith said:

I had a brainwave. I need your opinion. I have 18 x 550watt solar panels installed on my roof. 9 north and 9 west. My 8kw Sunsynk only have 2 mppt's. So I cannot add a third string on the east side of my house. But what if I install 6 x 620 watt panels on the east side, connect it to some sort of device that only allows one side to be used at a time. So let's say from 06H00 to 10H00 the device or switch cuts off the west side completely and only draw from the east side and then after 10h00 isolate the east side completely and only draws from the west side until 17H00. The device must switch over automatically with say a 1 minute delay before the west start giving electricity to the mppt. Can something like this work

I would say the easiest way to add the extra panels without interfering with the current setup is have a separate MPPT like a Victron 150/100 just for those 6 East facing panels.

Edited May 12, 20251 yr by Gandalf