GreenFields

Just a sanity check. What type of panels do you have connected to that 5kW Sunsynk inverter? To have 10 panels on only 1 MPPT sounds like a lot, but may be not if it's smaller-output panels. What readings for Watts and Volts are you seeing on the screen for MPPT1?

Just a layman's 2c worth. Agree with @Demo Not a trolley inverter or a plug-in-the-wall, and not a modified-sine-wave inverter, not an AGM battery or even rather not a drop-in Lithium alternative. Best a professionally installed good brand name system, with CoC, with BMS comms between inverter and battery, and a remote monitoring assistant. Maybe with some redundancy like 2x Pylontech USC2000 batteries instead of a single 5kWh battery, with a Victron MultiPlus-II GX - 48/3000/35-32. Again, not professional advice, just some thoughts you could discuss with an installer. Might surely be other better systems you could also consider.

As said by @Kalahari Meerkat , your system is a bit problematic. Normally the grid-tied string inverter would be connected to the AUX/Gen port and controlled as a micro-inverter. In this case you're using that port for your generator. I'd suggest to re-position the connection of your grid-tied inverter to somewhere between the CT coil and your grid meter. That way you could treat it as part of the grid from the point of view of your Deye inverter. The Zero-Export to CT function should then prevent you importing power from your grid-tie inverter to the Deye inverter; it will rather export to the outside grid past the meter. Together with that, you could set up a Time-of-Use schedule that allows a Grid Charge during the daytime, where "Grid" would then in actual fact be coming from your grid-tie, but not exclusively. Alternatively, why not transfer your solar panels to the Deye inverter, and just ditch the grid-tie inverter? Mine is gathering dust, it is simply obsolete in this setup.

Okay, so your best bet with these panels and inverter, if it's a choice between just these options, and if it's the typical Voc=50V-odd, then take 8x550W, but connect them all in series, ie. 8s, not 4s2p. It begs the question of whether you could do better with a different panel altogether, that has a higher Imp closer to 16-17A, so you could connect 5000W of panels more easily. Right now the Voltage is your limiting factor in a series string, and the current if you're thinking to go parallel.

Have to always ask, which inverter are you considering putting it on, and which make and model of panels are you talking about? The answer could be different depending on circumstances.

In line with @Sidewinder but I'd suggest a Greenrich 1.5C 7.5kW battery, the 8kW generator on the AUX port with auto-start, then around 35A of the 40A office loads designated as core essential loads for the load port, and then the rest of the office loads and the aircons on the non-essential grid port. Use the16kW Deye with around 20*550W (=11kW) panels connected at first, expandable to more later. Basically, rather take fewer panels in the beginning and divert that cost to at least the one battery. I know the goal is to save money more than anything else, but this will give you a more robust, stable system. Beyond that I'd suggest doing a study of your grid usage, ie. let it be measured over a couple of days, or just explain what loads you're running and when. Just considering that 4000kWh per month on a 1P line running at 55A full-power all day, in an 8-hour work day Monday-to-Friday, you should only be using 2225kWh during a normal month during work hours. How are you reaching 4000kWh pm? Just afraid some info is missing that could be useful in sizing the system.

What happens when you disconnect the grid at the main switch, and run solely off the backup inverter on its own 230V sine wave?

Extract below for info and discussion. I hope I'm wrong or over-hyping that impact, but I'm just imagining a train at the end of the tunnel. This is from the Eskom tariff doc, which has been updated with the restructured rates approved by NERSA on 18 February 2025. For tariffs appliable from 1 April 2025 to 31 March 2026 for non-local authority supplies, and 1 July 2025 to 30 June 2026 for local authority supplies. As discussed in other threads, the goal is to move toward a fixed-fee portion, and time-of-use tariffs for residential solar users. This will become effective right in the middle of the high-demand season, when the peak tariff per kWh will be R8.13 per kWh. That is not a typo. For many business users this type of tariff may be an everyday thing or they work around it. I'm guessing most everyday residential owners of grid-tied systems are not ready for it. If the changeover is anything like what happened when Nelson Mandela Bay Metro moved users to TOU tariffs, it could catch a lot of unsuspecting solar users with big bills come July and August, basically overnight, on a national scale. That's if you aren't changing your TOU settings to run exclusively from battery during peak hours, or if you don't have enough battery backup to cover cooking all the way from the evening, with enough left over for the morning rush (alternatively schedule a battery recharge from grid during the off-peak time). And keep your non-essentials like geysers, etc. on timers, away from operating during peak times if you can help it.

Not exactly overriding the zero export, it just introduces selling as a second priority. As opposed to "Selling First" mode when selling is... first priority. If you're in "Zero Export to CT" mode or otherwise "Zero Export to Load" mode, then by ticking the "Solar Sell" boxes you will indeed start exporting power once the battery is full, and if you've got surplus daytime PV energy. Bottom line, if you are not registered for export, then don't tick those options.

I wouldn't worry about it, as long as you're connected to the grid that can easily supply a surge of the iron turning on, or absorb the excess PV when the iron turns off. Even if you're not connected to the grid, my guess is that you'll have sufficient surge capacity and/or cooling capacity spare in your battery and your inverters to momentarily handle the 2kW or so when your iron goes on or off, so that a dump load is probably not needed.

Can't really comment without understanding the power demand of the business in greater depth. I think that just pure grid-tie is the wrong way to go. If you consider the Eskom tariff re-structuring that would be likely to force you into a fixed fee and time-of-use tariffs over the next period, then a hybrid inverter with possibility for battery backup will help you to manage your generation and demand much better, and give you flexibility down the road. I'd think, the 16kW Sunsynk/Deye would be best if you want up to 40 panels, but at least a 12kW could also be useful if you're sticking to 30 panels. Writing this to you as we've got the return of Stage6 loadshedding.

Okay, so 140A Max Charge could be a waste. Would then say, see if 180-190A charge is okay, if you simultaneously set the Grid Peak Shaving = 8000W.

Power was PV 1.54kW plus Grid 2.61kW, then minus 0.52kW load, and then some unspecified losses for self-consumtion and heat... left you with 3.37kW to divert to charging the battery at approx 54V charge Voltage. Could set Max A charge then to 140A and that should all together hopefully improve its overall behaviour. Otherwise, how much PV is connected in total?

Suggest you try to set: Grid Peak Shaving=8000W And tick/use Load Priority

What does City of Cape Town say about this? Will they still be allowing people to sell back unlimited power for profit, or will they just be doing net-billing also? All I can say in my humble experience of 10 years grid-tied to NMBM, it's really hard to do a long-term investment case when tariff structures change every other year.

Looking at it that way I have to agree, but then the supply crunch we had in SA as a result of loadshedding is not necessarily reflective of the global Solar industry. Graphs below are just drawn from Google searches, for China, AUS, & globally, and maybe there's some confirmation bias in it, but it does seem to suggest that panel price changes expressed as a currency value per Watt, have levelled out since the 2020's due to Silicon price increases, while lithium battery prices have been still coming down.

Just speaking as an outside observer, layman's 2c. The drop in solar panel prices probably ended 3 years or so ago, and the major revolution since then has been the drop in battery prices. I've seen articles indicating that raw materials alone make up around 60-70% of the cost of solar panels, and pricing is now much more driven by commodity prices than by the technological innovation, ie. it doesn't leave much more room for dropping the prices through improvements in manufacturing or economies of scale, if they still want to make a profit. You would basically need a radical innovation in using much cheaper materials or something similarly groundbreaking. I think the way to drop overall costs from here is to incorporate solar modules into the structure of other products. There have already been innovations like solar window blinds, solar roof tiles, solar windows, or even just using solar panels as carport roofs. The next step as I see it is to roll some of these out at scale.

Be very careful with making this decision. Note below, that Nersa has reportedly now approved the restructuring of Eskom's tariffs into a fixed fee and time-of-use fees, with some other changes. You cannot base your decisions & payback calculations on the people that installed solar before you because the rules of the game have just changed, and we'll only see how the dice land from 1 July onwards. Nersa approves restructuring of Eskom tariffs - Moneyweb That being said, if you go about it smartly, know your needs, choose and use your system wisely, it's surely possible to drop your costs now and especially in the long run. If you just slap something in without proper analysis, you could also be wasting lots of money.

Just a bit of OCD, cleaning up for in case you decide to change work modes later. Bottom line, just don't use solar sell unless you get approved for it by the municipality and get a new two-way meter to go with it.

Could've been something as simple as someone playing around with your settings. Anyways, System Work Mode Screen 1 is your issue. There where you've got the block selected "Zero Export to CT" - that part is okay - but right next to it you've got a block that says "Solar Sell." Take away the tick next to "Solar Sell." In fact, switch briefly to the work mode "Zero Export to Load" and just take away the "Solar Sell" tick there, and then switch back to "Zero Export to CT." You should be okay after that. Arguably like I said one could tweak some other stuff according to preferences, but already this should resolve your big issue of exporting power to the grid. I'm assuming that your CT coil is installed correctly by your installer.

Still not all the needed screens. But go through them all and set the following: GEN PORT USE - ignore that screen for now. Basic Setting: Ignore that screen for now. Battery Setting (Batt Set 3): Ignore that screen for now. No critical issues. Arguably could be tweaked, but not the cause of your issues. Battery Setting (Batt Set 2): Battery setting (Batt Mode): Set Max A Charge = 80A. And remove the tick for "Activate Battery" - leave it blank. System Work Mode (WorkMode4) - Tick all the boxes on that screen -every day with a box ticked against it. But now go back to all the other Work Mode screens (WorkMode1, WorkMode2, WorkMode3). Post images of those screens too. Especially the screen with "Zero Export to CT" and "Solar Sell" on it. Make sure that "Solar Sell" is disabled.

Okay, so it does look like you are exporting power into a prepaid meter, which you rather don't want to do because of the cost, nevermind that it's probably illegal to export power if you're not registered for it. Seems to be the 8kW Deye inverter, but I can't interpret the actual settings from these app screens. If this is correct, please send photos of the Work Mode screens, battery settings screen, and time of use screen.

The usual issue is where a pre-paid meter cannot distinguish between power purchased inwards and power exported out to the grid, so it treats everything it measures like a purchase. Please share all your details of your setup. Inverter model and all settings, and maybe graphs of your PV, grid usage, battery usage, gor a typical day.

What happens when you set all of the below: 1. Time-of-Use active, and 100% Batt percentage in all time slots. 2. Power = 0 in all time slots 3. Grid charge - no ticks, blank in all time slots 4. Zero export power = 80-100W

This type of question is best answered if one knows your loads, daily consumption, time of use, etc. But the basic principle is to run as many of your loads as possible during the day as first priority with timers, etc, then charge your batteries during the day, and run the batteries down as low as possible at night. Whether you want to keep a reserve for loadshedding is a different question. I'd suggest: 1. Zero-Export to CT. Without Solar-Sell if you can't export to grid. 2. Load Priority. 3. Activate Time-of-Use Schedule according to the below. Grid Charge Gen Time Time Power Batt 00:00 05:00 750 35 05:00 09:00 3000 20 09:00 16:00 3000 100 X 16:00 18:00 500 100 18:00 20:00 5000 70 20:00 00:00 3000 50 4. Battery Low warning = 15%, Battery Shut-down = 10%, Battery re-start = 25% 5. Maximum Charge/Discharge rate = 100A 6. System Work mode active every day. If you've got a time-of-use schedule, you could consider to turn off the timer on Sundays. When I do this type of setup, my typical usage pattern looks like below; I've got a fairly small system with my own little needs, but the principle is probably the same for bigger setups..