luckielab
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A lot of times that comes in the rambling parts, so def keep on with that, please!
Adding storage to my Enphase system
- Thread starter GXMnow
- Start date
400bird
Solar Wizard
A lot of times that comes in the rambling parts, so def keep on with that, please!
I'll second that!
400bird
Solar Wizard
They were running a sale and I'm close enough to real goods that I can pick up the inverter I ordered from AltE, so I probably did about the best I could. I didn't save $600, but I did ok.
GXMnow
Solar Wizard
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The shipping on the nearly 300 pound pallet was going to be close to $300 alone, and the sale chopped about $300 off the XW-Pro and a bit off of the Gateway and Conduit box as well. Going to pick it up is a big savings, but for me it would have been an 800 mile round trip. That chops into the savings.
Have you decided what you will be using for batteries yet? Schneider says you need over 440 amp hours, but that is not true. It will allow you to set it much lower, but you do need cells that can take a surge charge current to 140 amps without damage. That will probably never happen, but it could, and the last thing you want is a cell bursting before a fuse has a chance to blow. As quick as the XW-Pro is, if a very heavy load turns off with a lot of AC coupled power coming in, the power ends up going to the batteries before it can adjust. So far, I am very happy with the performance of these Chevy Bolt cells. My only issue so far has been the BMS sense lead failure. They have been online over 7 months now and the cells are solid as a rock. They have been charged to 85-90% and run down to 40-55% about 220 times now. Here is a snap of the BMS app right now.
Charging at 28.3 amps, up to 55.95 volts total, all of the cell voltages within 0.004 volts 3.995 to 3.999, and sitting at 16C to 17C battery temp. Current outside temp is 56F (13.3C) and the temp in my garage is 63.5F (17.5C). I am a bit shocked it held that warm overnight. I don't have heat in there, but the water heater does supply some warmth, and the sun is beating on the roof. The solar is cranking out 3,800 watts. So the solar is running everything in my house, charging the battery bank at almost 1,600 watts, and still pushing 1,000 watts out to So Cal Edison. The solar really performs when it is cool and windy but sunny with no clouds. I am hitting over 5 sun hours a day in Feb. and my panels are not ideally tilted, just at the roof slope, and not quite to the south.
400bird
Solar Wizard
My permit is written for 2* 14s strings of...
...chevy bolt batteries. Shh, don't tell anyone about the fire stuff.
That's part of the reason I've been following your thread.
But, I never had plans to charge to 100%, so I'm not concerned about the recall stuff. The Bolt in the driveway didn't catch on fire...yet, lol
And I've got to have the pack outside at least 5' from any building and property line.
I'm either going to buy and modify a construction storage box, or build a custom metal box.
...chevy bolt batteries. Shh, don't tell anyone about the fire stuff.
That's part of the reason I've been following your thread.
But, I never had plans to charge to 100%, so I'm not concerned about the recall stuff. The Bolt in the driveway didn't catch on fire...yet, lol
And I've got to have the pack outside at least 5' from any building and property line.
I'm either going to buy and modify a construction storage box, or build a custom metal box.
GXMnow
Solar Wizard
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I knew the conditions were good today with zero clouds, direct sun, and cool wind, but wow. All 16 microinverters hit clipping for 2 full hours, from 11:30 am to 1:30 PM over 3,800 watts. So I guess my solar panels are still meeting spec. The total for the day hit 25.3 KWH.
GXMnow
Solar Wizard
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I finally have some decent data with similar conditions with and without the battery bank. It is not a perfect comparison, but I think it shows the value of being able to time shift power, even if I do throw away almost a full kilo watt hour. Here is the solar production for Feb 21st of this year, with last year on the same day being the line plot. I did produce 4.3 more KWHs this year, so I need to take that into account.
The peak power in both cases was pretty close at 3.7 and 3.8 KW averaged from 12:30 to 12:45. There was some clouds last year that cause the dips, so it obviously had a bit less power coming in. Here are the two days showing the power from So Cal Edison for the same 2 days.
Last year, I was exporting about 2,700 watts in the noon hour. Great solar production, and not much usage. This year with the battery bank, the export only hit 1,300 watts in the same hour, but my battery topped out in the 1 pm hour, so export started going up, where it was falling last year. I think I want a bit more battery capacity, so I can store a bit more, and keep it exporting to 11 pm. Thanks to the better production this year, I did still hit about 2,300 watts exporting in the 2 PM hour. Solar was obviously falling in the 3PM hour both years, but it was still exporting. But at 4PM, last year, right as the rate jumps to the higher time of use, the solar was no longer keeping up and I had to start buying the more expensive power. This year, the battery took over, and ramped up as the solar fell off. Exporting about 500 watts, as well as supplying all the power for the house. The battery was able to keep feeding all my loads out to the end of the 8 pm hour. At 9 pm we go back to the low off peak rate, so I have the inverter shut down. So for the last 3 hours, I still buy an average of 800 watts or so, pretty close to last year.
The one thing you notice right away is that I did net use power last year, and net exported this year, but that is not completely valid. I did produce 4.3 KWH more energy this year. Last year I bought 1.49 KWH. If I had that extra 4.3 KWH of production... 1.49 - 4.3 = -2.81 KWH it looks like I would have exported 2.81 KWHs. So I must have also used a bit less power, but not a huge difference. I exported 3.52 this year, so even with cycling it into and back out of the battery, I still exported 0.71 KWH more than last year, after adding in the extra solar produced. Maybe we had a few less loads running, maybe the air compressor ran last year. Whatever, it is a tiny difference. I expect the battery cycle to waste a bit more than that, but it's not. I will do this for a few more days, now that I have some overlapping data with my trees trimmed back and the panels clean.
The peak power in both cases was pretty close at 3.7 and 3.8 KW averaged from 12:30 to 12:45. There was some clouds last year that cause the dips, so it obviously had a bit less power coming in. Here are the two days showing the power from So Cal Edison for the same 2 days.
Last year, I was exporting about 2,700 watts in the noon hour. Great solar production, and not much usage. This year with the battery bank, the export only hit 1,300 watts in the same hour, but my battery topped out in the 1 pm hour, so export started going up, where it was falling last year. I think I want a bit more battery capacity, so I can store a bit more, and keep it exporting to 11 pm. Thanks to the better production this year, I did still hit about 2,300 watts exporting in the 2 PM hour. Solar was obviously falling in the 3PM hour both years, but it was still exporting. But at 4PM, last year, right as the rate jumps to the higher time of use, the solar was no longer keeping up and I had to start buying the more expensive power. This year, the battery took over, and ramped up as the solar fell off. Exporting about 500 watts, as well as supplying all the power for the house. The battery was able to keep feeding all my loads out to the end of the 8 pm hour. At 9 pm we go back to the low off peak rate, so I have the inverter shut down. So for the last 3 hours, I still buy an average of 800 watts or so, pretty close to last year.
The one thing you notice right away is that I did net use power last year, and net exported this year, but that is not completely valid. I did produce 4.3 KWH more energy this year. Last year I bought 1.49 KWH. If I had that extra 4.3 KWH of production... 1.49 - 4.3 = -2.81 KWH it looks like I would have exported 2.81 KWHs. So I must have also used a bit less power, but not a huge difference. I exported 3.52 this year, so even with cycling it into and back out of the battery, I still exported 0.71 KWH more than last year, after adding in the extra solar produced. Maybe we had a few less loads running, maybe the air compressor ran last year. Whatever, it is a tiny difference. I expect the battery cycle to waste a bit more than that, but it's not. I will do this for a few more days, now that I have some overlapping data with my trees trimmed back and the panels clean.
GXMnow
Solar Wizard
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I think I may have found a much simpler solution to getting my Schneider XW-Pro to charge in the morning.
After 2 e-mails up and back with Schneider, I came up with an idea, and I tested it today. I left the "Recharge Volts" set down low at 50 volts. The "Grid Support Volts" was still set at 51 volts. So last night, it ran in Grid Sell from 4 pm to 9 pm, and stayed in invert powering the essential load panel for about another hour as it ran the battery down to 51 volts, and then went back into AC Pass Through. This morning, the battery was still sitting at 51 volts as I expected. But instead of raising the recharge volts setting to force it to start charging, I just had the Gateway send "Force Charger Mode" = "Bulk" and click apply. It went right into charge mode and topped up the battery until it completed a full Bulk and Absorb charge cycle, without changing any settings.
So instead of having to do multiple steps to change and check 2 32 bit registers twice a day, I can just poke one 16 bit register just once and it SHOULD trigger the charge mode. I will edit my PLC program and test my theory. This is a whole lot less handshaking I need to do to make this work. I will set the "Charge Block Stop" much earlier in the morning, and I can have my PLC just trigger when I want the charge to start. In my last replay back to Schneider tech support, I asked if they could forward a simple feature request to the programmers. Make one of the GPIO pins on the Gateway send the "Force Bulk Charge" mode command. Then I just need to give it a relay pulse and could use any cheapo PLC with a time of day clock. Of course, I want to get a bit smarter, I will tell it to start charging when the solar starts producing more than 1,200 watts. If I have a very weak solar production day, it will just sit at 51 volts, about 50% charge and not waste energy putting in and back out of the battery from the grid. If the solar comes up and triggers a charge cycle, but then clouds come out, it will do basically the same thing. It will partially charge, and then at 4 pm start exporting power, but it may just run 30 minutes until it hits the 51 volt shut down again. I think this is going to work.
My backup plan is not as slick. If I place a solid state relay between the grid and the XW-Pro ac1 input, I can have the microcontroller put all of my essential loads on battery power for an hour in the middle of the night. This could pull the battery down enough so that when I put it back on grid, it will start a charge cycle when charge block ends. To do this, I need the PLC to read battery voltage, and make sure to re-connect the grid when the battery voltage falls 0.2 volts below the "Recharge Volts" setting. I don't really like the idea of forcing my gear off grid though. Even with the fast 8 ms switch time, I still see the glitch and in the past, it has locked up the Enphase inverters. I sure hope that issue has ben fixed. I have not tested it yet.
After 2 e-mails up and back with Schneider, I came up with an idea, and I tested it today. I left the "Recharge Volts" set down low at 50 volts. The "Grid Support Volts" was still set at 51 volts. So last night, it ran in Grid Sell from 4 pm to 9 pm, and stayed in invert powering the essential load panel for about another hour as it ran the battery down to 51 volts, and then went back into AC Pass Through. This morning, the battery was still sitting at 51 volts as I expected. But instead of raising the recharge volts setting to force it to start charging, I just had the Gateway send "Force Charger Mode" = "Bulk" and click apply. It went right into charge mode and topped up the battery until it completed a full Bulk and Absorb charge cycle, without changing any settings.
So instead of having to do multiple steps to change and check 2 32 bit registers twice a day, I can just poke one 16 bit register just once and it SHOULD trigger the charge mode. I will edit my PLC program and test my theory. This is a whole lot less handshaking I need to do to make this work. I will set the "Charge Block Stop" much earlier in the morning, and I can have my PLC just trigger when I want the charge to start. In my last replay back to Schneider tech support, I asked if they could forward a simple feature request to the programmers. Make one of the GPIO pins on the Gateway send the "Force Bulk Charge" mode command. Then I just need to give it a relay pulse and could use any cheapo PLC with a time of day clock. Of course, I want to get a bit smarter, I will tell it to start charging when the solar starts producing more than 1,200 watts. If I have a very weak solar production day, it will just sit at 51 volts, about 50% charge and not waste energy putting in and back out of the battery from the grid. If the solar comes up and triggers a charge cycle, but then clouds come out, it will do basically the same thing. It will partially charge, and then at 4 pm start exporting power, but it may just run 30 minutes until it hits the 51 volt shut down again. I think this is going to work.
My backup plan is not as slick. If I place a solid state relay between the grid and the XW-Pro ac1 input, I can have the microcontroller put all of my essential loads on battery power for an hour in the middle of the night. This could pull the battery down enough so that when I put it back on grid, it will start a charge cycle when charge block ends. To do this, I need the PLC to read battery voltage, and make sure to re-connect the grid when the battery voltage falls 0.2 volts below the "Recharge Volts" setting. I don't really like the idea of forcing my gear off grid though. Even with the fast 8 ms switch time, I still see the glitch and in the past, it has locked up the Enphase inverters. I sure hope that issue has ben fixed. I have not tested it yet.
GXMnow
Solar Wizard
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I had to do this one more time.
Feb 25th 2020 and 2021 my Enphase solar produced almost the same power. It did taper off a bit more this year than last year, but the totals came out to 25.8 KWH this year vs 26.2 KWH last year. It also looks like the loads used in the house were very close. Here is the solar production.
Here is what the battery did this year.
The charge current does not follow the extra solar, but I have it dialed in so that it doesn't pull more than the solar makes on any normal day. The output current in the evening is not as flat, because it actually is adjusting to supply the loads and only push the desired amount back out to the grid side. From 4 pm to 5 pm, you can see the current ramping up. This is because the XW-Pro is measure the power going back to the grid, and when the solar is still making more power than the loads in the output panel, the XW-Pro is not taking from the battery yet. As the solar falls off, it starts pulling battery power to feed the loads, and I have it pushing about 3 amps back to my main panel. It can't adjust for changing loads in the main panel. So from 5 pm to 9 pm it is supplying all the power for my backup loads panel, and adjusting it's current to follow with just my set amps back to the main. At 9 pm, it stops pushing back to the main panel, but it keeps running the loads in the backup panel until the batter hits my grid support cutoff. On that day it was set to 51.5 volts. I have moved it down to 51 even, and then it stayed running out past 10:30 pm. This is not selling any to the grid, just using my own power in the evening instead of the solar selling it during the day.
Here are the 2 days, one year apart, from SCE showing my usage.
Last year without the battery
This year with the battery
The first big thing to notice is that I am still selling quite a bit during the day when the sun is up. But instead of pushing up to 3,000 watts, it is only 1,500 watts until the battery topped out. Then the 2 pm hour shot up to 2,000 watts as the sun was just starting to go down. I should push the charge start time a little later. At 9 am, you can see it was just covering the charge power and the house load. In the 3 pm hour it flips. The solar alone was down to just 500 watts, but now the battery is starting to output and holding it to 1,000 watts. Then the entire 4 pm to 9 pm time, the battery was pushing out about 500 watts on top of running the whole house. Obviously we turned on some heavy load in the 5 PM hour, I think it may have been the welder for 10 minutes. But for the whole hour, we only ended up buying 0.1 KWH. For the totals, last year with solar only, we pushed out 2.58 KWHs, and this year, storing a bunch and using it in the evening, we pushed out only 1.92 KWHs. But a good portion of that 0.66 KWH difference is from the solar producing 0.4 KWH less, so that takes care of all but 0.26 KWH. Some of that was lost due to the efficiency of the AC to DC charging and DC back to AC discharging of the battery. On that day, I pushed 7.4 KWHs into the battery bank, and got most of it back out. Assuming the difference was the 0.26 KWHs, I am doing way better than expected. That is only a loss of 3.4%. I don't think it is quite that good, we must have used a bit less power this year, even with that spike in the 5 pm hour.
Doing this study has certainly proved that it is worth cycling the power to save a bit off of the peak rate power. At $0.43 per KWH I went from buying 4.2 KWH at peak time to selling them 1.7 KWHs. So 5.9 x 0.43 = $2.54 savings during the peak time, but I sold them less power at the $0.22 price before 4 pm. I figure I sold about 6 KWHs less, so $1.32 for a net gain of $1.22 per day. Still does not sound great, but x 30 days, is $36.60 a month, over $400 per year, towards paying for the battery bank. During the summer I will have to see how much I can shift with the A/C running. I am being careful to not sell them more than about 500 watts during the peak rate time. When it is 100F outside, and my A/C won't stop, I still want to try and zero the power meter in that time frame. The A/C compressor pulls 14 amps at 240 volt. I don't think I have quite enough battery to run that for the whole 5 hour window. 5 x 3,360 = 16,800 or 16.8 KWHs. My total battery bank capacity is rated at 18 KWHs, but I am only charging to 85% and down to 20%. That would mean I could move about 11 KWH's safely. Even if I can offset 1/2 of that 16.8 KWHs, it will be a big help. It does sometimes cycle off, depending on how crazy the weather is. I might be able to push it up to saving nearly $2 per day with the AC running, without adding any solar panels. I am looking at putting 4 panels on my garage roof. Trying to decide of I should get 4 more Enphase microinverters, or just go DC to my battery bank. 4 x 400 watt panels with a good charge controller, in the summer sun here, could give me about 9.6 KWHs straight into the battery bank each day. The XW-Pro would barely ever need to charge at all.
Feb 25th 2020 and 2021 my Enphase solar produced almost the same power. It did taper off a bit more this year than last year, but the totals came out to 25.8 KWH this year vs 26.2 KWH last year. It also looks like the loads used in the house were very close. Here is the solar production.
Here is what the battery did this year.
The charge current does not follow the extra solar, but I have it dialed in so that it doesn't pull more than the solar makes on any normal day. The output current in the evening is not as flat, because it actually is adjusting to supply the loads and only push the desired amount back out to the grid side. From 4 pm to 5 pm, you can see the current ramping up. This is because the XW-Pro is measure the power going back to the grid, and when the solar is still making more power than the loads in the output panel, the XW-Pro is not taking from the battery yet. As the solar falls off, it starts pulling battery power to feed the loads, and I have it pushing about 3 amps back to my main panel. It can't adjust for changing loads in the main panel. So from 5 pm to 9 pm it is supplying all the power for my backup loads panel, and adjusting it's current to follow with just my set amps back to the main. At 9 pm, it stops pushing back to the main panel, but it keeps running the loads in the backup panel until the batter hits my grid support cutoff. On that day it was set to 51.5 volts. I have moved it down to 51 even, and then it stayed running out past 10:30 pm. This is not selling any to the grid, just using my own power in the evening instead of the solar selling it during the day.
Here are the 2 days, one year apart, from SCE showing my usage.
Last year without the battery
This year with the battery
The first big thing to notice is that I am still selling quite a bit during the day when the sun is up. But instead of pushing up to 3,000 watts, it is only 1,500 watts until the battery topped out. Then the 2 pm hour shot up to 2,000 watts as the sun was just starting to go down. I should push the charge start time a little later. At 9 am, you can see it was just covering the charge power and the house load. In the 3 pm hour it flips. The solar alone was down to just 500 watts, but now the battery is starting to output and holding it to 1,000 watts. Then the entire 4 pm to 9 pm time, the battery was pushing out about 500 watts on top of running the whole house. Obviously we turned on some heavy load in the 5 PM hour, I think it may have been the welder for 10 minutes. But for the whole hour, we only ended up buying 0.1 KWH. For the totals, last year with solar only, we pushed out 2.58 KWHs, and this year, storing a bunch and using it in the evening, we pushed out only 1.92 KWHs. But a good portion of that 0.66 KWH difference is from the solar producing 0.4 KWH less, so that takes care of all but 0.26 KWH. Some of that was lost due to the efficiency of the AC to DC charging and DC back to AC discharging of the battery. On that day, I pushed 7.4 KWHs into the battery bank, and got most of it back out. Assuming the difference was the 0.26 KWHs, I am doing way better than expected. That is only a loss of 3.4%. I don't think it is quite that good, we must have used a bit less power this year, even with that spike in the 5 pm hour.
Doing this study has certainly proved that it is worth cycling the power to save a bit off of the peak rate power. At $0.43 per KWH I went from buying 4.2 KWH at peak time to selling them 1.7 KWHs. So 5.9 x 0.43 = $2.54 savings during the peak time, but I sold them less power at the $0.22 price before 4 pm. I figure I sold about 6 KWHs less, so $1.32 for a net gain of $1.22 per day. Still does not sound great, but x 30 days, is $36.60 a month, over $400 per year, towards paying for the battery bank. During the summer I will have to see how much I can shift with the A/C running. I am being careful to not sell them more than about 500 watts during the peak rate time. When it is 100F outside, and my A/C won't stop, I still want to try and zero the power meter in that time frame. The A/C compressor pulls 14 amps at 240 volt. I don't think I have quite enough battery to run that for the whole 5 hour window. 5 x 3,360 = 16,800 or 16.8 KWHs. My total battery bank capacity is rated at 18 KWHs, but I am only charging to 85% and down to 20%. That would mean I could move about 11 KWH's safely. Even if I can offset 1/2 of that 16.8 KWHs, it will be a big help. It does sometimes cycle off, depending on how crazy the weather is. I might be able to push it up to saving nearly $2 per day with the AC running, without adding any solar panels. I am looking at putting 4 panels on my garage roof. Trying to decide of I should get 4 more Enphase microinverters, or just go DC to my battery bank. 4 x 400 watt panels with a good charge controller, in the summer sun here, could give me about 9.6 KWHs straight into the battery bank each day. The XW-Pro would barely ever need to charge at all.
GVSolar
Solar Enthusiast
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- 455
I'm not nearly as sophisticated as you are with programming and Schneider Voodoo - but I do know that being both DC & AC coupled in
a Schneider system gives you additional responsiveness/flexibility in system settings/menus. My totally off-grid home: AC coupled with 3kw of Enphase M-215s (SE facing - slam-bang variety of frequency shifting) plus DC coupled with 3kw (1.5 S facing, 1.5 W facing) of 250w panels, 10kwh of LFP, using all Schneider - SW4024, SCP, SCCs and combox. Seamless shifting from AC to DC couple charge/discharge - so my 2 cents -I recommend going with the DC addition - the Schneider MPPT 60-150 is a rock. Best.
a Schneider system gives you additional responsiveness/flexibility in system settings/menus. My totally off-grid home: AC coupled with 3kw of Enphase M-215s (SE facing - slam-bang variety of frequency shifting) plus DC coupled with 3kw (1.5 S facing, 1.5 W facing) of 250w panels, 10kwh of LFP, using all Schneider - SW4024, SCP, SCCs and combox. Seamless shifting from AC to DC couple charge/discharge - so my 2 cents -I recommend going with the DC addition - the Schneider MPPT 60-150 is a rock. Best.
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GXMnow
Solar Wizard
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The Schneider MPPT 60-150 is a nice box. I can find it for under $600, so it is not crazy expensive like the 600 volt one. But it is a tight fit for my system. The solar array voltage must be above the battery bank voltage, but below 140 volts. That is pretty tight. About the only array of panels that will fall between 60 and 140 volts is either 3 x 60 cell or 2 x 72 cell in series. I would probably have to use 2S 2P with 72 cell modules to get close to my desired power. I can only fit 4 across on my garage roof, maybe a 5th, but that does not help. I found Astronergy brand 365 watt panels that would work. 2S VOC works out to 96 volts. 2P ISC is 19.5 amps. Max power point works out to 78.76 volts, 18.54 amps, and 1460 watts. At just $257 per panel, that is not to bad. I am looking at about $2,000 up front cost without racking. That is a bit more than I want to spend right now, but if my work does start picking up, I could do it this year. But that is also a bit short on my power goal to fully handle my battery charging needs.
GXMnow
Solar Wizard
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Once again, Schneider tech support told me they don't care and closed my service ticket.
So I told them off in a fairly long e-mail. Basically, I will not be buying any of their gear again, and now recommending the OutBack Skybox. My plan with this changing world was to become an installer of battery backup systems for all of the grid tie solar in my area. I felt I had designed a great system, but with the stupid programming in the XW-Pro / Gateway system, it just won't do power time shifting on it's own. If they were willing to work with me at all, I could have sold many systems. There are literally a few thousand grid tie systems within just a few miles of me. For my own personal system, I will likely still get my PLC programmed and working, but I don't want to help Schneider sell any more units. And I won't be buying their charge controller.
So I told them off in a fairly long e-mail. Basically, I will not be buying any of their gear again, and now recommending the OutBack Skybox. My plan with this changing world was to become an installer of battery backup systems for all of the grid tie solar in my area. I felt I had designed a great system, but with the stupid programming in the XW-Pro / Gateway system, it just won't do power time shifting on it's own. If they were willing to work with me at all, I could have sold many systems. There are literally a few thousand grid tie systems within just a few miles of me. For my own personal system, I will likely still get my PLC programmed and working, but I don't want to help Schneider sell any more units. And I won't be buying their charge controller.
GXMnow
Solar Wizard
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We had a few days of crappy weather here. My typical solar output should be around 24 KWH a day at this time of year, but the last two week had some really bad days. One day was down at 8.3 KWH, a few more at 13 KWH, and 16 KWH. Yesterday was 13 again, and the output fell under 100 watts at just 3 pm. This triggered the Schneider XW-Pro to go into grid support mode as soon as the battery was fully charged. So it was running all of the load in my backup panel starting at 3 pm. Normally, the solar is easily taking care of that, and even still pushing some power back to the main panel. And the XW just waits until the peak rate time at 4 pm. And even after 4pm, most days, there is still enough solar, so the XW just ramps up as the solar falls off, but not this day, at 4pm, the output jumped up to push power back into my main panel. I had set the currents based on my "normal" usage and production. This was not normal. It ended up pulling the battery bank down to my 50% state of charge cut off at just 7:50 pm. That left me buying peak rate power for over an hour. Not too big of a deal, it still net saved me a bit over not having it, and it did still keep enough battery if I did have a power failure.
The system is working well, but I really do want to get my PLC controller working so it can monitor the solar production and adjust the XW inverter settings to maximize the battery usage. I also want to look into about 30-50% more battery capacity. Another 100 amp hours would be nice.
The system is working well, but I really do want to get my PLC controller working so it can monitor the solar production and adjust the XW inverter settings to maximize the battery usage. I also want to look into about 30-50% more battery capacity. Another 100 amp hours would be nice.
400bird
Solar Wizard
Wow, you pay way more daily attention to you PV output than I have! Apparently I produced 6.16 kWh yesterday, even with the output disconnected for most of the day while I was doing some wiring. On a good sunny day my average peak is just over 30kWh this time of year.
On your pack, whenever GM stops buying all the packs from totaled bolts, I'll probably have nearly half a pack left over. When I went looking last fall, I found 4 within a 45 minute drive. Right now, I can't find a single pack.
Originally I had planned on 2x 14s packs. But, the more talking you do about your system I'm thinking 3 or 4 might cover my needs better.
Hopefully, the packs become more available soon...
On your pack, whenever GM stops buying all the packs from totaled bolts, I'll probably have nearly half a pack left over. When I went looking last fall, I found 4 within a 45 minute drive. Right now, I can't find a single pack.
Originally I had planned on 2x 14s packs. But, the more talking you do about your system I'm thinking 3 or 4 might cover my needs better.
Hopefully, the packs become more available soon...
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GXMnow
Solar Wizard
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I would not say I pay a super amount of attention to my system production, but I do check it from time to time. And when I see something odd, or if someone asks a questions, I will look at my data for comparison. And today, I saw this.
Today was an unusual day for mid march. It started very cold, but the sun was out in force. My Enphase micros all ramped up quick and hit clipping by 11:45, and all 16 stayed in clip until 3 PM. 3,800 to 3,900 watts for 3 hours and 15 minutes straight. And they ramped down pretty slow too. All totaled, my system produced 28.0 KWH today. With 16 x 300 watt panels, for a total of 4,800 watts of raw DC rating, that works back to just over 5.83 sun hours. The solar irradiance calculator only predicts 5.69 sun hours for my location in march, with my panel angles. So my system is certainly very efficient. I outperformed the estimate by 2.5% after the efficiency losses in the inverters, and with the inverters clipping for over 3 hours.
Too bad I don't have near enough battery to store up what I didn't use during the day. I had to sell quite a bit of cheap power back to the grid. I need to decide what is more important, adding more battery capacity, or adding 6 solar panels on my garage roof to DC charge the battery bank?? If I add six 330 watt panels just laying flat, they could have made another 10 KWH's and my battery only needed 7.3 KWH to fully charge from running the house last night. I could have it run the house later and make use of another 3 KWH's, but most of that would be selling at the cheaper rate again. In any case, I still want to make sure I leave at least 4 KWH in the battery incase of an overnight power failure. With the DC coupled charge setup, it would eliminate the startup issues though. Even if I ran the system dead, the sun would stat pushing up the battery until it got high enough for the inverter to fire up and then the AC coupled Enphase would come online as well.
Even with my short charge (about 88% now) my current battery should be able to put out about 11-12 KWH each evening. And then the solar DC charge can put it back, And I won't need to trigger the XW into charge mode. I will need to log a few hot days with the A/C running and see where my consumption falls. I know the A/C compressor pulls about 14 amps at 240 volts when running, but I don't know the true duty cycle of how much it runs vs rests. Another 8-10 KWH of battery would be nice.
Today was an unusual day for mid march. It started very cold, but the sun was out in force. My Enphase micros all ramped up quick and hit clipping by 11:45, and all 16 stayed in clip until 3 PM. 3,800 to 3,900 watts for 3 hours and 15 minutes straight. And they ramped down pretty slow too. All totaled, my system produced 28.0 KWH today. With 16 x 300 watt panels, for a total of 4,800 watts of raw DC rating, that works back to just over 5.83 sun hours. The solar irradiance calculator only predicts 5.69 sun hours for my location in march, with my panel angles. So my system is certainly very efficient. I outperformed the estimate by 2.5% after the efficiency losses in the inverters, and with the inverters clipping for over 3 hours.
Too bad I don't have near enough battery to store up what I didn't use during the day. I had to sell quite a bit of cheap power back to the grid. I need to decide what is more important, adding more battery capacity, or adding 6 solar panels on my garage roof to DC charge the battery bank?? If I add six 330 watt panels just laying flat, they could have made another 10 KWH's and my battery only needed 7.3 KWH to fully charge from running the house last night. I could have it run the house later and make use of another 3 KWH's, but most of that would be selling at the cheaper rate again. In any case, I still want to make sure I leave at least 4 KWH in the battery incase of an overnight power failure. With the DC coupled charge setup, it would eliminate the startup issues though. Even if I ran the system dead, the sun would stat pushing up the battery until it got high enough for the inverter to fire up and then the AC coupled Enphase would come online as well.
Even with my short charge (about 88% now) my current battery should be able to put out about 11-12 KWH each evening. And then the solar DC charge can put it back, And I won't need to trigger the XW into charge mode. I will need to log a few hot days with the A/C running and see where my consumption falls. I know the A/C compressor pulls about 14 amps at 240 volts when running, but I don't know the true duty cycle of how much it runs vs rests. Another 8-10 KWH of battery would be nice.
Hedges
I See Electromagnetic Fields!
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Power ramped down linearly from max at 3:00 PM to zero at 7:00 PM.
If you added panels aimed at late afternoon sun, could you avoid draining battery (or drawing from grid) until later? (might be more pronounced in summer.)
I think it is cheaper to make kWh than to store in a battery, so would try to use production at a different time of day to reduce need for battery.
If you added panels aimed at late afternoon sun, could you avoid draining battery (or drawing from grid) until later? (might be more pronounced in summer.)
I think it is cheaper to make kWh than to store in a battery, so would try to use production at a different time of day to reduce need for battery.
svetz
Works in theory! Practice? That's something else
Someone's aligned for optimum year-round tilt ;-)
I'd add the panels, tilted as Hedges suggested (use microinverters if you can, their output will be off compared to the rest of the panels). Don't go crazy with the tilt, see table to right for diminishing returns. But, it's because I believe battery prices are going to fall more this year, and solar not so much. I could be all wet on that. |
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Is there anything you can alternatively do to bank energy? For example have a smart thermostat turn the internal temperature to 65 so you can coast through the evening hours without Air conditioning? Heat the hot water? Power up the EV? Run the dryer? Pop the evening's popcorn?
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Hedges
I See Electromagnetic Fields!
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Someone's aligned for optimum year-round tilt ;-)
I'd add the panels, tilted as Hedges suggested (use microinverters if you can, their output will be off compared to the rest of the panels). Don't go crazy with the tilt, see table to right for diminishing returns.
But, it's because I believe battery prices are going to fall more this year, and solar not so much. I could be all wet on that.
Is there anything you can alternatively do to bank energy? For example have a smart thermostat turn the internal temperature to 65 so you can coast through the evening hours without Air conditioning? Heat the hot water? Power up the EV? Run the dryer? Pop the evening's popcorn?
That graph looks suspiciously like just sine of angle to me, the area presented to the sun by a horizontal panel. It hits about 71% at 45 degrees.
The following link has a graph which starts off flatter, then falls more steeply. More like 92% at 45 degrees.
Figure 3. Direct normal intensity versus zenith angle and AM.
Download scientific diagram | Direct normal intensity versus zenith angle and AM. from publication: Performance analysis of high-concentrated multi-junction solar cells in hot climate | Multi-junction concentrator solar cells are a promising technology as they can fulfill the increasing energy...
www.researchgate.net
svetz
Works in theory! Practice? That's something else
Supposedly it's the maximum theoretical, as if you had a two axis solar tracker. Don't have the reference anymore so YMMV. On the other hand, in the paper cited the graph represents a "direct radiation on a horizontal surface" using a concentrator as shown to the right... |  |
Hedges
I See Electromagnetic Fields!
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I didn't go beyond the first web page from ResearchGate. The graph has notations like AM1.5D
Apparently AM1.5D refers to spectrum appropriate for tracking concentrator systems, and AM1.5G for non-tracking. Difference being diffuse light from surrounding sky, which wouldn't be focused through a concentrator system.
I think "1.5" refers to path length of sunlight through atmosphere.
www2.pvlighthouse.com.au
www2.pvlighthouse.com.au
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Apparently AM1.5D refers to spectrum appropriate for tracking concentrator systems, and AM1.5G for non-tracking. Difference being diffuse light from surrounding sky, which wouldn't be focused through a concentrator system.
I think "1.5" refers to path length of sunlight through atmosphere.
PV Lighthouse
The PV Lighthouse website is a free online resource for photovoltaic scientists and engineers. It provides calculators that simulate various aspects of solar cell operation.
PV Lighthouse
The PV Lighthouse website is a free online resource for photovoltaic scientists and engineers. It provides calculators that simulate various aspects of solar cell operation.
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- the air mass is 1.5 (where the sun is about 41° above the horizon, see the page "The air mass (AM)";
- the cell is tilted by 37° from the horizon (so the sun shines at an angle of 11.2° from the cell's normal vector);
- the cell has no optical concentration system, so the cell faces a hemisphere including the surrounding ground (which is light sandy soil); a spectrum that includes the blue sky and the surrounding ground is called a global spectrum, so the spectrum is called AM1.5g.
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