July 10, 20232 yr We recently took the plunge and installed 6x 555 Longi panels (wired in series) paired with a 5Kw SaColar hybrid Inverter and a pack of Sunpays Lithium Fe batteries (10 Kw total) We have an energy efficient household i.e. our daily load is pretty low (1.2 Kwh). Peaks when cooking to ±3 Kw mark for 30 minutes at most. Now we need to understand this (expensive) SOLAR. Daunting task! but, apparently, 6 panels * 555 [minus losses] = ±2.8 Kw per hour potential power. Daily Expectation = ±12-14 Kwh (based on 5hrs sun) The inverter, the data logger and the solar assistent / Pi all register PV voltage at ±91 and the PV current at ±13 amps which equates to the ±1.1 Kwh the system is generating (total ±6 Kw per day) System is coping i.e., power needs are being met. However, what niggles is why we have a 12-14Kwh system delivering a daily 6 Kwh ?? Is this acceptable ? Any feedback / recommendations would be appreciated. I should also mention that all laundry appliances + dishwasher are NOT on the inverter. These are on a separate phase and on the grid. House has 3 phase electricity.
July 10, 20232 yr Hi there The solar panels can only produce what you are using. You mention your loads are low, this would mean your panels will not produce a lot more than your loads are asking for. Once your batteries are full in the morning and if your loads are low then the panels production will also be low as there is nowhere for the power to go. I hope that helps a bit with understanding how the solar works
July 10, 20232 yr Author Hi thanks for this. Every bit of info helps.😀 I also need to correct the info I provided. The panels are wired in series but in pairs - so 3 pairs all the way to the combiner box and then in parallel to the inverter. This keeps voltage low and thus power from the panels ( I think ??) The installer says this is to prevent the low voltage inverter from being damaged. So it appears the panels are wired to ensure ONLY around the 1 Kwh of DC and the inverter is the bottleneck if we needed more power. Which raises another question. Would less costly panels have done an adequate job, given the inverter and current load? 🤔
July 10, 20232 yr 32 minutes ago, Karish said: So it appears the panels are wired to ensure ONLY around the 1 Kwh of DC and the inverter is the bottleneck if we needed more power. Does not really matter how the panels are wired they should still provide the rated power less losses when the loads demand it. BUT - if the inverter cannot handle the rated power then that's a whole other story, I am sure your installer would/should have matched the panels correctly to the inverter capabilities and your load/budget requirements. As @FixAMess mentioned, provide some more info then we can better advise/assist. Edited July 10, 20232 yr by WannabeSolarSparky
July 10, 20232 yr 3 hours ago, Karish said: 6x 555 Longi panels Roughly speaking this should give you around 3330W peak at 12pm regardless of how they are wired. Series keeps the amps down, but increases voltage, while parallel keeps the voltage down, but increases the amps, they produce the same watts. If your installer mentioned they need to be wired like that because you have a low voltage inverter then it sounds like he knows what he's talking about. 36 minutes ago, Karish said: So it appears the panels are wired to ensure ONLY around the 1 Kwh of DC and the inverter is the bottleneck if we needed more power. The inverter is not the bottleneck, your usage is. I doubt 3.3kW of panels is too much for the inverter, but you need to have loads to use that power or the inverter won't produce it. Try switching on the kettle and toaster at the same time and see how much power you can get out of the panels at peak, you should be able to get more than 2kW, close to 3kW. 36 minutes ago, Karish said: Which raises another question. Would less costly panels have done an adequate job, given the inverter and current load? You may have been able to do with fewer panels with such low consumption, but you might need them on very cloudy days to get the batteries charged. I think, to make the best of your system you should consider moving some of the laundry items on to the inverter (at least the dishwasher), just be sure not to use them all at the same time or you will overload the inverter, that way you should start to save on electricity costs. Edit: P.S. don't mix up kW and kWh... kW is at a point in time, but kWh is over a duration. So, if you have 1kW for 1 hour, you have 1kWh, but 1kW for 2 hrs gives you 2kWh etc. Edited July 10, 20232 yr by jumper
July 10, 20232 yr I doubt that you are only using 1.2kwh per day. If it is correct and the battery is full your panel power has nowhere to go. As you see 6kwh produced per day I wonder where is the other 4.8kwh going. May be some units are used wrongly as @WannabeSolarSparky already indicated.
July 10, 20232 yr 9 hours ago, Karish said: We have an energy efficient household i.e. our daily load is pretty low (1.2 Kwh). Peaks when cooking to ±3 Kw mark for 30 minutes at most. That's VERY low. Is that what the house is demanding or what you now draw from the meter? With any system, the panels will produce only what they have to. More accurately, the inverter will only draw what it has to. My system works hard in the morning. On a good day the battery is charged by 11:30 or so. Thereafter the inverter draws just enough PV power to service the load. In turn, I have moved as many loads as possible into the sunlit hours, so our load at night is low, and we easily make it through the night on our battery.
July 13, 20232 yr Author Hello, Some specs:- Inverter Mode Specs for 5KVA off grid Inverter (SaColar) - based on Growatt I believe) Output Voltage Waveform - Pure Sine Wave Output Voltage Regulation - 230 Vac±5% Peak efficiency - 93% Overload Protection - 5s@150% load; 10s @110-150% Nominal DC input Voltage 48Vdc Charge Mode Specs Battery Voltage - 48V Charging Current @Nom Input Voltage Default : 30A, max 60A Solar Charging Mode Max PV array Open Circuit Voltage - 145Vdc PV Array MPPT Voltage Range - 60-115Vdc Min battery voltage for PV charge = 34Vdc Max charging current - 140Amp Default charging Current - 60 Amp Are there any others needed? In response to suggestions that the if the household load increased inverter would pull more power I honestly have not observed that. If kettles & microwaves are used inverter pulls power from battery to supplement. Inverter is set to only use GRID if there is insufficient power from PVs and/or battery Snapshot from PV Butler 10.24 am 13th July 2023 uploaded Given the behaviour we see I must say we would be nervous to increase the load until we know the system can actually produce more solar energy. Right now I still have my doubts. Image attached shows system using battery power to supplement load requirement.
July 13, 20232 yr 46 minutes ago, Karish said: Hello, Some specs:- Inverter Mode Specs for 5KVA off grid Inverter (SaColar) - based on Growatt I believe) Output Voltage Waveform - Pure Sine Wave Output Voltage Regulation - 230 Vac±5% Peak efficiency - 93% Overload Protection - 5s@150% load; 10s @110-150% Nominal DC input Voltage 48Vdc Charge Mode Specs Battery Voltage - 48V Charging Current @Nom Input Voltage Default : 30A, max 60A Solar Charging Mode Max PV array Open Circuit Voltage - 145Vdc PV Array MPPT Voltage Range - 60-115Vdc Min battery voltage for PV charge = 34Vdc Max charging current - 140Amp Default charging Current - 60 Amp Are there any others needed? In response to suggestions that the if the household load increased inverter would pull more power I honestly have not observed that. If kettles & microwaves are used inverter pulls power from battery to supplement. Inverter is set to only use GRID if there is insufficient power from PVs and/or battery Snapshot from PV Butler 10.24 am 13th July 2023 uploaded Given the behaviour we see I must say we would be nervous to increase the load until we know the system can actually produce more solar energy. Right now I still have my doubts. Image attached shows system using battery power to supplement load requirement. Panels producing only 1000W and 700W from battery. Indications are on a sunshine day the panels could produce 2800-3200W. Currently my 2.5kw PV is producing 1.8kW in Gauteng.
July 13, 20232 yr On 2023/07/10 at 11:17 AM, Karish said: 6x 555 Longi panels On 2023/07/10 at 11:17 AM, Karish said: The inverter, the data logger and the solar assistent / Pi all register PV voltage at ±91 and the PV current at ±13 amps On 2023/07/10 at 1:55 PM, Karish said: The panels are wired in series but in pairs - so 3 pairs all the way to the combiner box and then in parallel to the inverter. Looks like these panels produce approx 13A at Pmax, so in 2S3P, you should be getting around 3x that, around 30A. From you inverter specs this is the correct wiring and it can easily handle that many amps. It looks to me like there is a problem on 2 of the parallel strings... maybe fuses or wiring issue in the combiner box?
July 13, 20232 yr Author 27 minutes ago, jumper said: Looks like these panels produce approx 13A at Pmax, so in 2S3P, you should be getting around 3x that, around 30A. From you inverter specs this is the correct wiring and it can easily handle that many amps. It looks to me like there is a problem on 2 of the parallel strings... maybe fuses or wiring issue in the combiner box? OK - thank you. Will get this checked because I have always felt there may be something not quite right.
September 5, 20232 yr Author Hello, It's taken a while to report back because Stephen Rebello - recommended to me by this forum was snowed under when I first contacted him. Wow! What service he and his team offer. We have had some good service over the years but this outfit is out of the ordinary. So, before he came on site I gave him access to Solar Assistant. He found the setting that was throttling the PV output. BUT noticed odd inverter behaviour in that it was not a smooth curve from early morning to midday. On-site he found mostly a good install in terms of wiring, fuses, circuits etc so he turned his attention to the communications side. Solar Assistant - inverter was not getting data from the battery so he hooked the battery up to the inverter and Solar Assistant from then on, showed up the accurate SOC. He theory was : now that the inverter has access to battery data it will possibly behave differently (the MPPT) and we should see the smooth curve expected as the sun rises and reaches peak strength at around midday. He was spot on. That is exactly what we are seeing. and along with proper settings the panels are today for the first time performing to specification. If this all sounds like he popped in solved the problem and left - do not be misled. He spent a lot of time going through the system: component by component, DB board wiring, climbed on the roof to check the panels......to fully inform himself whilst educating us as well, every step of the way. We now really understand our solar installation and finally speak a wee bit of its language. Happy Days!!! and huge thanks to R&D Energy and the Forum.
September 8, 20232 yr Hi @Karishthanks for such a wonderful review. Glad we could get your system going!!!
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.