June 26, 20196 yr Hi all, I was looking at this chart from yesterday and I thought I'd share it since it shows how nicely my hybrid grid-tied setup is working. Shows the advantage of the grid-tie approach even without council feed-in. The blue is the power coming from the panels. The green is shortfall that is being drawn from the grid. The purple is power going into (-ve) or out of the batteries. The brown shows how much power the inverter is pushing back to the grid side, and the red line is how much is going to the "essentials" circuits. Since the inverter was grid-tied it essentially feeds the grid and the essentials together. You can see that power from the panels goes first to the essentials and the grid side, trying to reduce draw from the municipality down to zero. If local demand is met and there is still excess from the panels then it goes to charge the batteries. If we don't have enough local power from the panels then what I do make is still 100% used and the nett difference drawn from the municipality. When the sun is gone then power is drawn from the batteries so the excess from the day is used in the evening. This was a high usage day - hot water, electric oven and etc - but in the middle of Cape Town winter I managed to use up 13.7kWh from my 3150Wp setup - looking at this chart none of the sunshine went to waste. I'm going guesstimate that that is twice the yield I could have got from a non-grid-tied setup.
June 26, 20196 yr 2 minutes ago, Elbow said: I'm going guesstimate that that is twice the yield I could have got from a non-grid-tied setup. From the first watt early morning to the last watt early evening we are saving on our Eskom bills. I'm still under 600 units per month, even now in winter, and that is with a 2.1kw array and batteries on "always charged" (they are old). Four more panels have arrived, just waiting for the installer then I have will have 3.5kw array. Want to see the inverter run at it's max of 2.4kw continuous most of the day see, with a perfect bell curve, for when the dishwasher and 2 geysers are on, staggered.
June 26, 20196 yr Author 15 minutes ago, The Terrible Triplett said: From the first watt early morning to the last watt early evening we are saving on our Eskom bills. I'm still under 600 units per month, even now in winter, and that is with a 2.1kw array and batteries on "always charged" (they are old). Four more panels have arrived, just waiting for the installer then I have will have 3.5kw array. Want to see the inverter run at it's max of 2.4kw continuous most of the day see, with a perfect bell curve, for when the dishwasher and 2 geysers are on, staggered. Hi @The Terrible Triplett, I also have a few more panels that I want installed - I asked Mike to let me know when he is in the neighbourhood so maybe we should share the cost of getting him down to install. Like you I can keep my usage below 600 units which is when the higher prices kick in. Its obvious with the cold weather I need something to heat the water more efficiently than an ordinary high pressure cylinder and element. Or at least a geyserwise or timer to get it to heat in the daytime.
June 26, 20196 yr 13 minutes ago, Elbow said: Or at least a geyserwise or timer to get it to heat in the daytime. Two geysers on two geyserwise times set to run 12pm-2pm and 2pm - 5pm - when I have the best position ito solar. 10-12pm is dishwasher. It is going onto a timer soon, that you can switch it on at night and walk away. 🙂 The average 500w loads should fit with the above 2kw loads into 2.4kw.
June 27, 20196 yr 20 hours ago, The Terrible Triplett said: Two geysers on two geyserwise times set to run 12pm-2pm and 2pm - 5pm - when I have the best position ito solar. This is very interesting as one can see the impact of the geysers. It seems the solar power is supplemented with grid power when they come on. We have something very similar happening except it uses battery power, not grid. This effectively results in additional cycling of the batteries. I want to investigate the possibility of replacing the 2 kW geyser elements with 1 kW. It will take longer to heat up but I have enough time, not enough PV power. Has anyone tried this before?
June 27, 20196 yr 33 minutes ago, Niel said: ... can see the impact of the geysers. ... 2 kW geyser elements with 1 kW ... Jip, watched the data for a few weeks, saw after 12pm is the best production and lowest consumption. Went from 3kw to 2kw to fit the inverter grid tied max with the +-500w general load in the 2.4kw limit. Now I am adding more panels, from 2.1kw to 3.5kw - winter production the core decision. 220ah 24v bank is too small for the array AND it is getting old, so Keep Always Charged. 🙂 1kw on say a 150l will take very very long. From 17deg to 65deg: 2kw takes about +-3 hours. So that could mean a 1kw will take about +-6 hours. You may run out of good sunlight hours depending on what other loads are running.
June 27, 20196 yr 1 hour ago, The Terrible Triplett said: Jip, watched the data for a few weeks, saw after 12pm is the best production and lowest consumption. Went from 3kw to 2kw to fit the inverter grid tied max with the +-500w general load in the 2.4kw limit. Now I am adding more panels, from 2.1kw to 3.5kw - winter production the core decision. 220ah 24v bank is too small for the array AND it is getting old, so Keep Always Charged. 🙂 1kw on say a 150l will take very very long. From 17deg to 65deg: 2kw takes about +-3 hours. So that could mean a 1kw will take about +-6 hours. You may run out of good sunlight hours depending on what other loads are running. We have a solar collector as well. At worst we need to heat from about 20'C to 47'C. Three hours should be enough. The second geyser is for guests only and not often used. So I think it should work. The problem is finding the 1 kW element.
June 27, 20196 yr 36 minutes ago, Niel said: We have a solar collector as well. At worst we need to heat from about 20'C to 47'C. Three hours should be enough. The second geyser is for guests only and not often used. So I think it should work. The problem is finding the 1 kW element. I had independent elements make me up a 1kw element: https://independentelements.co.za I supplied them with my existing element which was dead and they used the flange and base and fitted a 1kw element to it. I guess they could make the element any size you like I think they charged about R500
June 27, 20196 yr 3 hours ago, Niel said: This is very interesting as one can see the impact of the geysers. It seems the solar power is supplemented with grid power when they come on. We have something very similar happening except it uses battery power, not grid. This effectively results in additional cycling of the batteries. I want to investigate the possibility of replacing the 2 kW geyser elements with 1 kW. It will take longer to heat up but I have enough time, not enough PV power. Has anyone tried this before? Thats pretty much what I did, I swopped out my 4kw element with a 1kw element and put my geyser on a time switch to only turn on during daylight hours. The water takes longer to warm up but is warm by the time I need it, works fine for me
June 27, 20196 yr Author 9 hours ago, Niel said: This is very interesting as one can see the impact of the geysers. It seems the solar power is supplemented with grid power when they come on. We have something very similar happening except it uses battery power, not grid. This effectively results in additional cycling of the batteries. I want to investigate the possibility of replacing the 2 kW geyser elements with 1 kW. It will take longer to heat up but I have enough time, not enough PV power. Has anyone tried this before? For my inverter you can have it behave either way - use the batteries if they have charge and the panels aren't adequate, or only use the battery if there is nothing coming from the panels. We've talked here on Powerforum many times about hot water - It can work for sure to use a lower power element. But I think for me (for most people?) a thermal hot water system makes the most sense. CoCT limits how much panels I can have and so putting up a solar geyser is like installing a very efficient off-grid system.
June 27, 20196 yr 27 minutes ago, Elbow said: We've talked here on Powerforum many times about hot water - It can work for sure to use a lower power element. But I think for me (for most people?) a thermal hot water system makes the most sense. CoCT limits how much panels I can have and so putting up a solar geyser is like installing a very efficient off-grid system. I agree and our solar heater works beautifully 6 to 8 months of the year. But I'm curious about your comment about CoCT limiting solar panels. As far as I'm aware, they limit inverter generation capacity (which includes PV panels and batteries), not PV panel capacity? Am I missing something?
June 27, 20196 yr 1 hour ago, Elbow said: CoCT limits how much panels I can have and so putting up a solar geyser is like installing a very efficient off-grid system. Where is that published? They limit the inverter feedback to the grid, but not the amount of panels you want to put up, or have I missed something?
June 28, 20196 yr CoCT limits the size of inverter (on grid-tied systems only) which in turn limits the possible amount panels as most inverters can only take a factor of 1.2-1.5x the size of inverter. So indirectly CoCt is limiting the number of panels on grid tied systems
June 28, 20196 yr 1 hour ago, PeterP said: CoCT limits the size of inverter You mean SANS and NRS regulations are regulating the inverter max. 🙂 Nowhere is it stated, that I can find, that I cannot go say 7kw on panels on my 3kva inverter. As long as the inverter, when grid tied, does NOT exceed the breaker limit, I can add all the panels I want. I.e. if I want to generate 3.5kw from the panels consistently I need at least 4-4.5 kw of panels mounted. Edited June 28, 20196 yr by Guest
June 28, 20196 yr 1 hour ago, The Terrible Triplett said: You mean SANS and NRS regulations are regulating the inverter max. 🙂 Nowhere is it stated, that I can find, that I cannot go say 7kw on panels on my 3kva inverter. As long as the inverter, when grid tied, does NOT exceed the breaker limit, I can add all the panels I want. I.e. if I want to generate 3.5kw from the panels consistently I need at least 4-4.5 kw of panels mounted. You can add all the panels you like - the question is whether your inverter will like it....some apparently just throttle once it reaches max capacity, others might melt from what I understand. Some newer Axperts will just throttle at 4kW and you get a nice flat 4kW line the whole day - others have a max for a reason.
June 28, 20196 yr 25 minutes ago, PeterP said: ... the question is whether your inverter will like it. True. But the he point was ... to avoid miscommunication ... 15 hours ago, Elbow said: CoCT limits how much panels I can have ... They do not. The limit the inverter size yes, not the panels. And on that we agree ... 27 minutes ago, PeterP said: the question is whether your inverter will like it. So to be 100% crystal clear, no misunderstanding for future readers, the inverters design limits imposes the max panel limits, not the CoCT regulations. 🙂
June 28, 20196 yr Author 14 hours ago, The Terrible Triplett said: Where is that published? They limit the inverter feedback to the grid, but not the amount of panels you want to put up, or have I missed something? I'm sorry - you are right. I wrote loosely. Practically for me my inverter 3kVA rating limits how much sun I can turn into power which practically speaking limits how many panels I can use particularly since the inverter is designed for a single high voltage string. I would put up a second inverter and panels in off-grid setup but then I might rather put up a thermal solar which is more compact and efficient.
June 29, 20196 yr On 2019/06/26 at 2:44 PM, Elbow said: Hi all, I was looking at this chart from yesterday and I thought I'd share it since it shows how nicely my hybrid grid-tied setup is working. Shows the advantage of the grid-tie approach even without council feed-in. The blue is the power coming from the panels. The green is shortfall that is being drawn from the grid. The purple is power going into (-ve) or out of the batteries. The brown shows how much power the inverter is pushing back to the grid side, and the red line is how much is going to the "essentials" circuits. Since the inverter was grid-tied it essentially feeds the grid and the essentials together. You can see that power from the panels goes first to the essentials and the grid side, trying to reduce draw from the municipality down to zero. If local demand is met and there is still excess from the panels then it goes to charge the batteries. If we don't have enough local power from the panels then what I do make is still 100% used and the nett difference drawn from the municipality. When the sun is gone then power is drawn from the batteries so the excess from the day is used in the evening. This was a high usage day - hot water, electric oven and etc - but in the middle of Cape Town winter I managed to use up 13.7kWh from my 3150Wp setup - looking at this chart none of the sunshine went to waste. I'm going guesstimate that that is twice the yield I could have got from a non-grid-tied setup. Curious to know what the monitoring system/software is, and what hardware is in use? Thanks.
June 30, 20196 yr Author On 2019/06/29 at 7:26 AM, Blinkwater9 said: Curious to know what the monitoring system/software is, and what hardware is in use? Thanks. Hi, i use Openenergymonitor. Emoncms drew the charts. The data gets in from current transformer probes and from data from the inverter, the pylon batteries. All together I have dozens of measurements. the system is a Infinisolar 3kva hybrid inverter, 9 x 350Wp panels in a single string and 2 Pylon US2000B batteries. .
June 30, 20196 yr 2 hours ago, Elbow said: Hi, i use Openenergymonitor. Emoncms drew the charts. The data gets in from current transformer probes and from data from the inverter, the pylon batteries. Can I ask how you are getting the DC battery usage data into eMon ?
July 1, 20196 yr Author 23 hours ago, Sean said: Can I ask how you are getting the DC battery usage data into eMon ? Sure - I have a Raspberry Pi that is connected to the Inverter using USB and to my Pylon batteries using RS485. I adapted code found on Github to read from the inverter and batteries and publish data to Emoncms over MQTT. Here's an example of what is pulled from the inverter: { "time":1561972946, "InverterTime":"20190701112308", "TotalProduction":846, "GridVolts":221.1, "GridWatts":-1505, "GridHz":50.0, "GridAmps":1.2, "LoadVolts":221.1, "LoadWatts":225, "LoadHz":50.0, "LoadAmps":1.0, "LoadPercent":9, "DCVoltsPBus":412.6, "DCVoltsSBus":412.6, "BatteryVolts":49.7, "BatteryPercent":77, "PVWatts":1958.0, "PVVolts":345.4, "InverterWatts":1730, "Temp":39.0, "BatteryChargeMode":"A", "BatteryChargerIsOff":0, "BatteryChargerIsConstantVoltage":0, "BatteryChargerIsConstantCurrent":1, "BatteryChargerIsFloat":0, "BatteryChargeAmps":0.4, "BatteryFloatVolts":52.0, "BatteryMaxChargeAmps":25.0, "BatteryBulkChargeVolts":52.5, "InverterWatts": 1730.0, "PVWattsQDVPR": 1958.0, "RemainingCapacityQDVPR": 1570.0, "BatteryWatts": -228.0 } And here is the data that comes from a battery: Send { "time":1561973045, "VoltageUpperLimit":53.25, "VoltageLowerLimit":47.0, "MaxChargeAmps":25.0, "MaxDischargeAmps":-25.0, "BatteryCycles":56, "BatteryVoltage":49.922, "BatteryAmps":5.5, "BatteryWatts":274.57099999999997, "BatterySOC":47.0, "RemainingAh":23.5, "RemainingWh":1173, "MinutesToRun":9999, "CellMaxVoltage":3.7, "CellLowVoltage":3.05, "CellUnderVoltage":2.9, "cellVoltage0":3.328, "cellVoltage1":3.328, "cellVoltage2":3.329, "cellVoltage3":3.328, "cellVoltage4":3.33, "cellVoltage5":3.328, "cellVoltage6":3.328, "cellVoltage7":3.328, "cellVoltage8":3.327, "cellVoltage9":3.328, "cellVoltage10":3.33, "cellVoltage11":3.327, "cellVoltage12":3.327, "cellVoltage13":3.327, "cellVoltage14":3.329, "highestCellVoltage":3.33, "lowestCellVoltage":3.327, "cellImbalancePct":0.0, "temp0":22.0, "temp1":21.0, "temp2":21.0, "temp3":21.0, "temp4":21.0, "highestTemp":22.0, "lowestTemp":21.0 } to emon/pylonPPTBH02198838124
July 1, 20196 yr Ah thanks, I thought you'd found a way of feeding a DC shunt of sensor data directly.
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