At present one 8kW Sunsynk with one string [10x415 pv and 10.4kW batteries] are more than enough to carry the business through the day and the essential loads [CCTV, alarm, floodlights, fridges] during the night - it is a hybrid system which adresses the rainy season so utility usually is available. Now we will add a geyser and a few aircons which will exceed the inverters capacity yet we anticipate to add about 30 panels…. in short, will I have to add an inverter in parallel or is there a way to compensate with the panels in Auxillary Mode as on image?
EDIT: I was advised to get a second inverter, increase panels and for now keep the batteries as they are due to the fact that daytime load will increase drastic yet night time will stay more or less the same and can be augmented with grid power if need be
On my Sunsynk 8KW, I have my Aux Output wired permanently to my two solar geysers, via two Eskom linked relays.
My two older electrical geysers were retrofitted with ITS hybrid solar water heating systems that use an SR81 geyser controller, which is pre-programmed to heat at different times during the day, when I have excess solar production available.
So, if Eskom is up, then my geysers will be heated via my Aux output from excess solar, if needed at all, but I did not want a scenario where Eskom is down and I use up all my battery capacity to heat up the geysers, hence the relays that @JacoDeJongh fitted between the inverter Aux output and my geyser elements.
If Eskom is down, the relays disconnect the inverter and my batteries from the geyser resistive element, but the water will still be heated up via the roof fitted evacuated tube collectors, as the circulation pumps are not on the Aux output and still runs via the normal inverter output.
It’s great to get details of a control system like this. So often I find people unwilling to dive into their control system and describe the pros and cons of it. This topic of powering the geyser with excess solar power gets me into hot water time and time again
You don’t elaborate on whether this a domestic installation or not. The electricity usage profile matters when designing (and running) a system.
I would do my calculations by excluding water heating. 30 panels is a lot so if that number can be reduced then that’s great. The advantage of the water heating load is that it’s not (initially) an essential load. It behaves much like charging batteries. There are many options to tackle this as opposed to essential loads.
Your 8kW inverter is still an 8kW inverter, no matter how many panels you have on the roof. That’s how much power it can provide continually. It may well continue to be adequate at night, but may not be during the day. So either it will trip when demand on the backed up side exceeds the 8kW, or will send what it can to the non-backed up circuits, and those circuits will draw from the grid to make up the difference.
A second inverter will give you 16kW of solar power (from panels or retrieved from batteries) at any one time. You will service a lot more of your load and reduce what you draw from the grid.
Internalised, unarticulated ideas often have a shortcoming. I remember reading a book which had the admirable quote “how do I know what I think until I hear what I have to say?”
We need to get our ideas out there, even if only to hear them echoed back. It allows to “hear” our ideas better.
I used to have a boss I would talk to about any smart ideas I had. He understood the game: half the time he wouldn’t be paying any attention. Hed just randomly interject “ah” or “hmmmm” as I was explaining whatever it was. The trick was that I verbalised it. Sometimes I wouldn’t get to the end, because a shortcoming would be revealed.
Sometimes, if he were listening, he’d ask “what about the flow gate arrays” or something I hadn’t thought of. Another benefit of getting the idea “out there”.
Amen! hence the great name “Energytalk” , we need soundboarding, articulation and the importance of the art of asking questions, or ‘prompting’ as AI would have it!
