PowerUser Posted July 27, 2022 Share Posted July 27, 2022 3 hours ago, WannabeSolarSparky said: Fortunately I still have my Growatt spf5000ES that I should actually hook up into my system and reconfigure exactly how I have everything wired up. Ideally for Off-Grid I should have 2 of the growatts. Probably better to go for 2 x 5kW Axperts models which can run on solar only when the grid is not present. This way with dead batteries, you can still have power. Quote Link to comment Share on other sites More sharing options...
WannabeSolarSparky Posted July 27, 2022 Author Share Posted July 27, 2022 30 minutes ago, PowerUser said: Probably better to go for 2 x 5kW Axperts models which can run on solar only when the grid is not present. This way with dead batteries, you can still have power. The growatts spf5000es too can run pretty well without batteries zsde 1 Quote Link to comment Share on other sites More sharing options...
WannabeSolarSparky Posted July 27, 2022 Author Share Posted July 27, 2022 Just cannot ask for a better day to do these tests Day 3 going pretty well and had the timers set nicely to keep all the loads nicely within the inverter specs Been "loadshedding" since 7:24 this morning. Geyser came on correctly this time, I also set the crypto rig to switch off when the geyser comes on and to switch on again when the geyser switches off That left plenty power to allow me to run the kettle or toaster while the geyser was charging With all the use through the day the battery has also managed to fully saturate by 15:10 The automation even switched the one crypto rig back on to use the extra solar that's still left for the afternoon after the batteries got to saturation point. zsde 1 Quote Link to comment Share on other sites More sharing options...
Bobster. Posted July 27, 2022 Share Posted July 27, 2022 5 hours ago, WannabeSolarSparky said: On the batteries side you should aim for a minimum of 400ah to even consider a move to going fully off-grid and even then you would need to carefully manage your usage to have reserves for those cloudy days. This is the truth. We've just had an overcast day in my hoekie of Johannesburg, and my system serviced all the loads but the battery was nowhere near 100% when the PV started tailing off in the PM. To be off grid, you need the battery capacity you mention (double what I have) AND the panels and inverter(s) to charge them in reasonable time. Plus, as you note, the discipline to manage your large but finite resources. Piper and WannabeSolarSparky 1 1 Quote Link to comment Share on other sites More sharing options...
TimCam Posted July 27, 2022 Share Posted July 27, 2022 6 hours ago, WannabeSolarSparky said: 2x 100ah batteries are just not going to be enough to go fully off-grid. Yip, I have a base load of 1.2 kW, and would need at least 40 kW of batteries to go off-grid. With 20 kW of batteries, I could "limp" along off-grid, and maybe use the generator to help if needs be. To go off-grid on a small solar system will require to many sacrifices for most people. Quote Link to comment Share on other sites More sharing options...
TimCam Posted July 27, 2022 Share Posted July 27, 2022 (edited) Double post. Edited July 27, 2022 by TimCam Quote Link to comment Share on other sites More sharing options...
WannabeSolarSparky Posted July 27, 2022 Author Share Posted July 27, 2022 (edited) 11 minutes ago, TimCam said: Yip, I have a base load of 1.2 kW, and would need at least 40 kW of batteries to go off-grid. With 20 kW of batteries, I could "limp" along off-grid, and maybe use the generator to help if needs be. To go off-grid on a small solar system will require to many sacrifices for most people. Correct, my wife and I both are already very very low power users (since we started with solar a few years ago we started adjusting how we do things) We are pretty much at our limits with what we are willing to sacrifice as apposed to what we gain from solar. Any further and it would no longer be fun to use solar. Currently with these last 3 days of testing we have brought our eskom units down to less than 1 unit per day, that in our books is already a massive WIN and we have already gained massive insights into how far we can still push our little system. Now to simply keep adjusting the system and maybe adding 2 more batteries and hooking up the growatt then by the time eskom make up their minds how they are going to do the feedin tarrfis and fixed fees then we should know if we are going to go Full-off-grid or feed in to the grid with a few extra panels to negate any fixed fees In my books either way we win for a small added outlay. Edited July 27, 2022 by WannabeSolarSparky Piper, TimCam and zsde 3 Quote Link to comment Share on other sites More sharing options...
WannabeSolarSparky Posted July 27, 2022 Author Share Posted July 27, 2022 Just past 5pm and there is still some 8amps going in to re-saturate the batteries(wife used the microwave) before the DREADED SHADOWS creep over the panels Dylboy and TimCam 2 Quote Link to comment Share on other sites More sharing options...
WannabeSolarSparky Posted July 27, 2022 Author Share Posted July 27, 2022 Gonna give an "loadshedding" all-nighter a bash Batteries had a good level of saturation today They may well last till our 1st cup of coffee in the morning before the morning sun hits the panels zsde 1 Quote Link to comment Share on other sites More sharing options...
WannabeSolarSparky Posted July 27, 2022 Author Share Posted July 27, 2022 Today's 12 hour loadshedding chart, although the "loadshedding is still continuing trying to go all night Still ended up having a bit of wastage this afternoon once the batteries reached saturation point. Quote Link to comment Share on other sites More sharing options...
WannabeSolarSparky Posted July 27, 2022 Author Share Posted July 27, 2022 This does NOT need further explanation zsde 1 Quote Link to comment Share on other sites More sharing options...
TiaanSmit Posted July 28, 2022 Share Posted July 28, 2022 I'm hoping to lower my grid dependence to 2-3kwh per day when my system is eventually installed. Dammit hubble whats the delay in stock arrival WannabeSolarSparky 1 Quote Link to comment Share on other sites More sharing options...
iiznh Posted July 28, 2022 Share Posted July 28, 2022 14 hours ago, WannabeSolarSparky said: Still ended up having a bit of wastage this afternoon once the batteries reached saturation point. I have noticed you use battery voltage in your graphs. Do you not have SOC available? I have noticed that voltage is a pretty useless metric on my battery. The SOC % works much better Quote Link to comment Share on other sites More sharing options...
WannabeSolarSparky Posted July 28, 2022 Author Share Posted July 28, 2022 Just now, iiznh said: I have noticed you use battery voltage in your graphs. Do you not have SOC available? I have noticed that voltage is a pretty useless metric on my battery. The SOC % works much better Let the debate begin SOC as reported by the builtin bmses on LiFePo4 factory built batteries is not a good reflection of the actual state of the batteries. Especially considering the crappy bmses these factory built batteries come with. Voltages are a bit closer to reality (In my case anyway) The correct way is to use a decent coulomb counter on each battery, I have not had time yet to get mine setup on each battery, also still waiting for some parts from china to complete that. Or a decent BMS like the jk bmses, but with these factory built batteries you will void your warranties. And stock in SA for them is scarce, also waiting for mine to arrive from China zsde and iiznh 2 Quote Link to comment Share on other sites More sharing options...
zsde Posted July 28, 2022 Share Posted July 28, 2022 43 minutes ago, WannabeSolarSparky said: Voltages are a bit closer to reality (In my case anyway) and even then you have to question the accuracy. The average user accepts what's presented from a single source. For most that would be the Inverter. And on closer inspection you find that the V reporting is not even accurate. Which value do you trust. The Inverter, the battery BMS? Take a Fluke just to find out that none of them are correct. Here is an example of a bit earlier. The two snapshots were seconds apart. Compare the Inverter and Battery BMS values. 52,7V vs 53,3V Just before the battery hit 100% I checked again. Inverter 53,6V BMS 53,4V and then I used the Fluke on the Battery terminals and that was floating between 53,1 and 53,2V. So it becomes a selective choice in terms of whichever reading makes you feel good. Does that make any of the readings correct? Definitely not. The Manufacturer will of course use whatever the BMS stored when it comes to warranty claims. The fact that your best AVO can prove that their BMS is not accurate is an inadmissible argument from their perspective. WannabeSolarSparky 1 Quote Link to comment Share on other sites More sharing options...
WannabeSolarSparky Posted July 28, 2022 Author Share Posted July 28, 2022 6 minutes ago, zsde said: The average user accepts what's presented from a single source. For most that would be the Inverter. And on closer inspection you find that the V reporting is not even accurate. Which value do you trust. The Inverter, the battery BMS? Take a Fluke just to find out that none of them are correct. Here is an example of a bit earlier. The two snapshots were seconds apart. Compare the Inverter and Battery BMS values. 52,7V vs 53,3V Correct, most of the time for the average user it is what they are comfortable in trusting/relying on. Myself being a big DIY enthusiast and tinkerer of note, I prefer the trial and error method to find what works best for me. I am also a BIG fan of Andy's Off Grid Garage and he has shown, by demonstration, a massive amount of info on how these LiFePo4 batteries work and how to get the most out of them without destroying them Supergeek and zsde 2 Quote Link to comment Share on other sites More sharing options...
iiznh Posted July 28, 2022 Share Posted July 28, 2022 30 minutes ago, WannabeSolarSparky said: I am also a BIG fan of Andy's Off Grid Garage and he has shown, by demonstration, a massive amount of info on how these LiFePo4 batteries work and how to get the most out of them without destroying them Also love Andy's channel. I have a 16S2P (200Ah ... that is more like 240ah DIY battery with a Daly 200A BMS). The current shunt to measure the SOC works pretty well. If I throw 60A charge current towards my battery and it is pretty full (75%) you will find that the cell voltages will rise towards 3.40 - 3.55V. Overall voltage will measure close to 55V. When you limit the current to 10A then sudden battery voltage drops back to 53-54 volts. The voltage appears to be a function of the direction of which you letting current flow and how much current is flowing. The moment I put a load on the battery the 3.5V cells are back to 3.35V and the battery shows 52-53V. I cycle my battery between 40% and around 80-90%. On good days I might hit 100% (but the winter sun angle limits my production). Trying to cut Eskom out of the picture but every now and then I still need to buy a unit here and there WannabeSolarSparky 1 Quote Link to comment Share on other sites More sharing options...
TiaanSmit Posted July 28, 2022 Share Posted July 28, 2022 @WannabeSolarSparky what has been your average kwh production over the past 3 days? Quote Link to comment Share on other sites More sharing options...
WannabeSolarSparky Posted July 28, 2022 Author Share Posted July 28, 2022 2 hours ago, TiaanSmit said: what has been your average kwh production over the past 3 days? @TiaanSmit it has averaged out to 676 watts per hour. That is measured continuously from 26/7 6am till 28/7 17:50 My essential loads over the same 3 days time-frame averaged in at 539 watts per hour. Today to the right on the chart also show that picture perfect cloudless days are NOT perfect for solar Also noteworthy from the chart is that there is not really too much difference between West And East facing panels. Another takeaway from the data is that my 8 connected panels are NOT enough to power my loads and fully charge/saturate my batteries over the same period of time. Need to add in my 2 extra east facing panels, but I suspect even that will not really be enough to keep the batteries correctly saturated. May need to add another 2 west facing. And if I eventually add in those 2 missing batteries then I would need to almost double up on the panels to get the same saturation levels. Quote Link to comment Share on other sites More sharing options...
WannabeSolarSparky Posted July 28, 2022 Author Share Posted July 28, 2022 On the plus side yet again, eskom is getting almost zero from us now May just end up running like this for a long time Maybe just connect every now and then to saturate the batteries if needed. Dylboy and TimCam 2 Quote Link to comment Share on other sites More sharing options...
TimCam Posted July 28, 2022 Share Posted July 28, 2022 1 hour ago, WannabeSolarSparky said: Maybe just connect every now and then to saturate the batteries if needed. Yip, Keep Eskom as an emergency battery charger. WannabeSolarSparky 1 Quote Link to comment Share on other sites More sharing options...
WannabeSolarSparky Posted July 28, 2022 Author Share Posted July 28, 2022 Self Loadshedding Is Becoming a thing at our home If you cannot go fully off-grid then at least aim for 12 hours or more per day if possible You WILL save a load of cash to then spend on further upgrades zsde and Supergeek 2 Quote Link to comment Share on other sites More sharing options...
WannabeSolarSparky Posted July 29, 2022 Author Share Posted July 29, 2022 (edited) Ok some more tweaks to happen today. I am moving the geyser back to the non-essentials side. The sunsynk 5kw just not suited to have that heavy load connected. It leaves way too little room for other appliances like my kettle and toaster which is essentially my essentials Also trying to finish the frame for my 2 missing panels to be added into the east string I really need that extra 1000watts for the battery charging. Edited July 29, 2022 by WannabeSolarSparky Supergeek 1 Quote Link to comment Share on other sites More sharing options...
WannabeSolarSparky Posted July 29, 2022 Author Share Posted July 29, 2022 (edited) Still some essentails non-essentials confusion about my setup This should help Edited July 29, 2022 by WannabeSolarSparky Quote Link to comment Share on other sites More sharing options...
WannabeSolarSparky Posted July 29, 2022 Author Share Posted July 29, 2022 (edited) Almost made 3 days off-grid, then the rain came... Going to have to buy those extra batteries. And then would have to get more panels to charge the extra batteries. Something tells me this never ends Edited July 29, 2022 by WannabeSolarSparky Nexuss and Supergeek 2 Quote Link to comment Share on other sites More sharing options...
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