GreenFields

Open to correction. Okay, so as I'm understanding this, your neighbour installed an off-grid inverter with battery back-up only, ie. with no solar panels to generate any of his own power. This is good for backup to have power when you need it when Eskom goes down, but there are inherent losses that WILL give him a bigger bill at the end of the day. It's firstly the battery and inverter's self-consumption, ie. like adding another two useful appliances onto your household that don't generate any power by themselves but keep draining constantly. Then there's the losses of putting power into the battery from grid, and returning power back from it, especially if he's got the inverter in a mode that prioritizes draining the battery each day. You never get back all that was put in. Best would probably be some kind of UPS-mode or SUB-priority, solar then utility and then as a last option the battery. It is unlikely that this type of inverter will be able to feed power back to the grid. Best thing is probably to add panels.

If you buy at that price, even if they are totally honest and deliver as promised, you were robbed.

Need more info. I'm not sure how to interpret this question. Firstly, your footer says you've got an 8kW Sunsynk inverter with 9900W of panels and 3x5kWh batteries installed. With this setup you can technically definitely export power to the grid if your installation has municipal or Eskom approval. If you have a 5kW inverter and 5kWh battery with no solar panels, you've got no means of generating your own electricity for export. At best you could draw energy from the grid and feed it back, if that makes financial sense for you. What do you mean by "Chinese" make? Deye and Solis are two Chinese brands making grid-tied and hybrid inverters that are capable of feeding back. If you've got any off-grid inverter, anything that's not grid-tied, then you can't export with it.

Layman's opinion, MUST be checked by a professional what your options are. With this combination of panel and inverter, you could go for up to 8 panels per series string. Any more and you'd risk exceeding the recommended max Open-Circuit Voltage, and most likely you'd be damaging the MPPT. With this configuration you'd not be able to use up to the maxmimum 5500W PV input power that the inverter can accept, the 8 panels would just add up to 4400W per inverter. If that works for you, great. If not, I'd suggest to investigate the route of going parallel anyway, or else using a different panel with a lower Voc, but higher current for the second inverter.

It is possible with a Deye inverter to put a limit in the battery discharge level, and on the discharge power rate, within the settings, to manage it in line with what your battery's specifications demand. And as I said earlier, in your setup with 2x5kW inverters, and 4x5kWh batteries, check the maximum discharge rate per battery and per inverter, but you appear to have enough capacity on-hand to handle your loads.

First I hear of this limitation, but maybe some cleverer people know better. You've got an inverter and battery that can output up to 10kW of power, which is probably enough for your heaters. The concern would be, if you only have 40% battery capacity left at that time during summer, then you'll probably have less battery capacity left in Winter, due to shorter days, less intense sun, and longer nights. If you're down to say 30% battery at the same time in Winter, then you'd probably not be able to run the heaters for long enough before reaching shut-down capacity of maybe around 20%.

The Solis spec sheet indicates noise levels below 65dB(A), while Deye indicates below 55dB. [The current linked Deye shows the un-weighted dB rating, while the previous Deye indicates the A-weighted noise levels as up to 55dB(A)]. Reading between the lines, it seems to come down to Solis having more robust cooling that operates up to 4000m altitude, while Deye is only rated to 3000m altitude. Don't have any personal experience of either, but since it seems to matter to you, I'd try to personally listen to each in action and compare before buying.

Your inverter has got two MPPT solar inputs. It is okay if you use different Watts of panels on the different inputs. So if you still have your 9x 250W-270W string, that would be perfect to add onto the second input. I think you could run into problems if you just use 4 of the 270W panels. Check the panel specs, you'll be probably close to the lower end of the 120V-385V solar range on Vmp. It would be better if you could somehow fit at least 5, or better yet, all 9.

My 2c. I just don't think your statement is universally true. What do you mean by "standard mode of operation" I'd suggest to use the terminology "ac-coupling" and "dc-coupling" of battery storage to draw clearer lines. In your case with your off-grid inverters, they are DC-coupled, ie. the solar panels convert energy and transfer to the battery, all using DC. And then in parallel to the battery, the DC/AC inverter can supply 230V AC onward to your loads. These are not grid-tied inverters in the sense of being embedded into the national grid for export of power back to Eskom. On the opposite end would be pure grid-tie inverters like micro-inverters, that convert DC from the solar panels straight to 230V AC, but they do not have any further DC output for battery power storage, they just send to grid. It's possible to add a second (battery) inverter for storage at the same location to form a micro-grid, and in that case, it would convert the AC-output of the micro-inverter back into DC for the battery. That would be AC-coupling of battery storage. In the middle would be the typical grid-tied hybrid inverters like Sunsynk/Deye, however it's difficult to speak of "standard" operational functioning being around AC. Yes, the output of the inverter is AC, and it is embedded into the grid for export through the bi-directional load port just like a grid-tied inverter. On the DC-side it also receives solar DC inputs to the MPPT's, for DC-coupled storage to the batteries, just like your DC-coupled Axpert-type. However it is also capable of AC-coupling to a micro-inverter on the AUX port. AC-coupling might just not be considered the "standard operation" but the capability is still a given. I hope this makes sense to frame it like this. Open to other views.

Could be an option also to install a heat pump and run it off the battery at night. To be weighed against the ongoing cost of gas, and if you've got spare battery capacity.

Personal 2c, on paper it seems like a very good option, but I think only you can make that call depending on how you plan to use the battery. If you are recommended to use only 7kW of discharge power from the battery, while the inverter is rated at 8kW output, is that really a significant sacrifice? If you're mainly running baseload through the night plus the odd appliance and electronic devices, that's probably not an issue, but if you've got a peak consumption with the geyser and kitchen/kettle/microwave/stove and aircons etc combining daily, that could easily push against the 7kW limit and over, and that might be too much to do it regularly. That being said, it's not a 7kW hard limit, since the batteries are rated for a max of 200A charge/discharge, while the inverter can only charge/discharge 190A at most. So you're not able to ever reach or exceed the battery's continuous rated capability of 10kW max power, you're just advised to not to push close to it on a regular basis. Touching 8kW once in a while like during a bout of loadshedding should in theory not be an issue. And if you're on-grid, and if the Solis has got the same sort of discharge-current-limit feature like the Deye inverter, you could set the peak draw from battery to 140A easily, and just get the rest from the grid for those times when you exceed 7kW household demand.

You'd need around 25kW or more worth of panels, and 60kWh or more worth of batteries, with the MPPT's to go with that. It's probably beyond the scale that most residential locations can support. Maybe investigate whether you have the option to stay on-grid and change to a time-of-use tariff, then you could add those 6 more panels and maybe 2-3 more batteries. You'd then set it up to carry you through peak hours on battery, run on solar by day, and save money with off-peak power rates at night.

It's also for controlling the diversion of battery power towards non-essential loads in the presence of the grid, or for selling battery power to the grid. A scenario where it could be useful is with a time-of-use tariff, buy cheap to store and use or sell later during peak times. Other scenario if there's Eskom load reduction, if you want to keep using the stove or geyser on non-essential. I'd just put it in anyway.

Rather not. Usually the shaded part of the string would lower the output on the entire series string. If you want to avoid buying new panels for now, you could try to transfer two panels from the North-string, one to each of the East and West strings.

I'm going on memory from datasheets I've seen in the past, such in the link below. If the specs have changed, or if there are different versions, I'd defer to your manual. Either way, you need strings longer than 3. https://www.solarwaysuppliers.co.za/wp-content/uploads/2014/01/5kW-Deye-Sunsynk-Hybrid-PV-Inverter-Datasheet.pdf

The startup Voltage is 150V. And 125V is actually the shutdown Voltage. As above, you need at least 4 panels in series per string, and if you can feed each to its own PV input, that'll be best.

Personal opinion only. Even without considering electrical compliance, you may well be in breach of the lease contract by installing alterations to the property without consent. Before starting a fight with anyone, I'd start by re-reading your lease carefully, and worst case taking off any of your own equipment, and restoring it to original state, or the lease could be cancelled out from under you. I'd ask for the landlord to install a different system, with own full sub-db and sub-meter for each home, ie. for you and the other tenant. You are neither a landlord nor a bank to the other tenant, I doubt that's part of your obligations under your lease to be a post-paid provider of electricity. Either way, before things get ugly, make sure worst case you're prepared to move.

Would've had to set Battery Priority or set TOU grid charge, neither of which I wanted. Details are fuzzy. Suggest really you experiment yourself. I just know it's not the same.

Rather always connect the external CT coil when you are connected to the grid, and especially if you have non-essential loads connected. There is a clear difference between "Selling First" and using Zero Export to Load or to CT with "Solar Sell" enabled. It relates to the immediate flow of power to/from the battery, and you'll notice a difference when changing between the battery priority or load priority settings. With "Selling First" you could export without charging the battery, it will stay at its level and slowly lose charge with inverter self-consumption. With Zero Export + Solar Sell modes, you could set your battery to charge by through the TOU settings, and the solar sell will be delayed or given a lower priority until your battery's requirements are met. Or something like that. Haven't done it in a while. You could play around with settings to confirm.

My understanding was that in the Northern Cape only has a small transmission line that is already saturated with PV. Even if you could fill the Karoo with panels you couldn't really power the mines and smelters on it without massive investment in the grid. But that would leave room still for battery storage to supply through the three-quarters of the day, night and evening and morning, when the sun's power is either low or absent.

Still awaiting the afternoon pic to be more sure. But from what's seen here, it's very likely with 135V, that you've got the wrong type of panel installed. Vmp on the typical Canadian Solar or JA Solar or Jinko panels of that size is around 42V, so 42x4 would give you around 165V. If your panels heat up, or as the MPPT shifts closer to Vmp of 31.4 per panel, you're likely to be bordering on the inverter's shut-down Voltage of 125V. If you install just one panel more that should dramatically improve the reliability of power generation throughout the day to around 10-12kWh, but you'd still be faced with the issues of being over the inverter manufacturer's short-circuit current protection specs, and that your peak generation will be limited by the 13A limit of the inverter. That's your cheapest option, but I'd still suggest to start over with 4 new panels. Except if your afternoon pic shows something entirely different.

It's possible, the difference has to be low, but just the Wattage isn't the full picture. Panel Voltage specs must be compared, and this can vary even if Watts are similar.

Try this: On the inverter's screen, find the Status Page, and then give the values for Volts in the blocks for Solar Power 1 & 2. My guess is it's around 125Volts, give or take a bit, when the sun is shining.

Please confirm the exact make & model of your Trina solar panel, or take a pic of the back data label on your panel. Just a quick Google Search, and I found this Trina Solar 545W panel: This panel is not suitable on your 5kW Sunsynk inverter. Even if you put on more panels to increase the Voltage and get it to start up, the problem is that the current rating (Imp and Isc) of that panel is too high. On the assumption/risk that you could have this panel - again, you should please check and confirm, and if it's indeed the same, then get an entirely new set of suitable panels. It's not about the brand or the Wattage, in this case it would be about the current. Maximum rated power 545W Voc 37.7V Vmp 31.4V Isc 18.52A Imp 17.37A Efficiency 20.90% Mechanical warranty 12 years Linear output warranty 25 years Supplier SKU TSM-DE19-545

I rather wouldn't do that. These panels are connected in series, and if you add another panel onto the string, you'd be skirting with the upper end of the allowable Open-circuit Voltage. @CaziquesYou cannot add any more panels in series. The issue as I see it on this series setup is the current limitation that the less-sunny panels could place on the more-sunny panels at any time of day. Improvement should be to place all the panels facing in the same direction, either all North or all West, if it should remain in series. Option 1. Assuming you have enough space in one direction to fit all the panels. Otherwise if you want to place them in parallel, Option 2, then drop one panel from the West-side string, or add one more to the North string, to keep it to the same number, 5+5, or 4+4. Not a mix and match of different numbers either side. Note it's also not clear what's the maximum current input on the MPPT from the specs, but the installer can check that. The simplest to solve all these issues is probably to use a Sunsynk, maybe a 5kW, like the installer suggested, Option 3, but it might not be the cheapest. Then you can go with up to 6 panels per MPPT, but I think 4 North and 5 West will be just fine, as long as you split them into two separate series strings, one per MPPT.