I'm a solar novice who is struggling with a 5 month old system. I have 22 Qcell 340 W panels with 1 SMA TL class 7700 inverter producing the electricity and, for battery backup, a Sunny Island 6048 with RS 485 and Web box and a SMA Smart Former (120/240) and 4 Deka AGM 8D size batteries. In the installation the electrician created an emergency panel with only 110 circuits. Full disclosure - what I just wrote about the SMA products is Greek to me; I copied it off the proposal.
My wife and I just spent 5 days off the grid in the wake of Hurricane Irma. This was our first significant test of our new emergency battery backup system. I would give it a grade of C at best. My needs were modest - a freezer, small refrigerator and a fan. My batteries were sufficient to get us through the night, but only if I started with a 90% charge.
My installer told me my system should go into float mode at 80% charge. However, it routinely went into float when the batteries were in the 60 something percent range - with the panels putting out only 9 or 10 watts. If I did nothing, at the end of the day I found myself with only 65 to 75% to get me through the night. If I rebooted the system when it was in float, that would sometimes cause the system to return to charging the batteries with whatever the panels are producing (2K to 5500K watts), but other times, for no reason that's clear to me, the panels would just continue to charge at 9 or 10 watts and at the end of daylight I had substantially less than a full charge. One night I got up in the middle of the night to check the charge and found it at 45%. I shut down the refrigerator (the freezer was already off) and turned off the fan but by morning I was down to 31%. After spending the rest of the night on a hard tile floor (A Florida trick to cool off a little), we were having some serious second thoughts about the wisdom of going solar.
There are a couple more things I should mention, not knowing if they are relevant: 1. The problem with the system going into float mode and staying there, seemingly in error, also happens when we do have power. I was told that this is to protect the system when we are not using enough electricity in the house, but when I start using more electric - the A/C goes on or I start charging my car - the system stays in float mode. If I don't reboot, and sometimes even when I do reboot, it will stay in float the rest of the day no matter how much power I'm using and we lose a half day or more of solar power that could be going back to the net meter. 2. When the system was installed, the installer told me (and I may not have this 100% right) that he was, contrary to the SMA default, going to set it up so that the batteries would get a trickle charge whether the system was or was not in Bypass mode.
I've tried to deal with this through the installer - who seems like a very smart electrical engineer - but his answers are usually vague or way over my head. I don't know if the problem is with the installation or if a qualified person can make some adjustments so that, when off the grid, it doesn't go into float mode until the batteries are fully charged. I'm also wondering if, when on the grid, it can be made to automatically reset itself so the solar panel production isn't wasted without me going through multiple reboots until I see more than 9 or 10 watts on the inverter readout. Or is this a poor SMA design for which I have no recourse? I would like to understand my options.
I don't have a clue, and will be very grateful for any advice you can give me that will improve the functionality of my system. We went with solar primarily because we want to be environmentally conscious, but in the new world of climate change getting the battery backup right is also very important to us. Thank you!
My wife and I just spent 5 days off the grid in the wake of Hurricane Irma. This was our first significant test of our new emergency battery backup system. I would give it a grade of C at best. My needs were modest - a freezer, small refrigerator and a fan. My batteries were sufficient to get us through the night, but only if I started with a 90% charge.
My installer told me my system should go into float mode at 80% charge. However, it routinely went into float when the batteries were in the 60 something percent range - with the panels putting out only 9 or 10 watts. If I did nothing, at the end of the day I found myself with only 65 to 75% to get me through the night. If I rebooted the system when it was in float, that would sometimes cause the system to return to charging the batteries with whatever the panels are producing (2K to 5500K watts), but other times, for no reason that's clear to me, the panels would just continue to charge at 9 or 10 watts and at the end of daylight I had substantially less than a full charge. One night I got up in the middle of the night to check the charge and found it at 45%. I shut down the refrigerator (the freezer was already off) and turned off the fan but by morning I was down to 31%. After spending the rest of the night on a hard tile floor (A Florida trick to cool off a little), we were having some serious second thoughts about the wisdom of going solar.
There are a couple more things I should mention, not knowing if they are relevant: 1. The problem with the system going into float mode and staying there, seemingly in error, also happens when we do have power. I was told that this is to protect the system when we are not using enough electricity in the house, but when I start using more electric - the A/C goes on or I start charging my car - the system stays in float mode. If I don't reboot, and sometimes even when I do reboot, it will stay in float the rest of the day no matter how much power I'm using and we lose a half day or more of solar power that could be going back to the net meter. 2. When the system was installed, the installer told me (and I may not have this 100% right) that he was, contrary to the SMA default, going to set it up so that the batteries would get a trickle charge whether the system was or was not in Bypass mode.
I've tried to deal with this through the installer - who seems like a very smart electrical engineer - but his answers are usually vague or way over my head. I don't know if the problem is with the installation or if a qualified person can make some adjustments so that, when off the grid, it doesn't go into float mode until the batteries are fully charged. I'm also wondering if, when on the grid, it can be made to automatically reset itself so the solar panel production isn't wasted without me going through multiple reboots until I see more than 9 or 10 watts on the inverter readout. Or is this a poor SMA design for which I have no recourse? I would like to understand my options.
I don't have a clue, and will be very grateful for any advice you can give me that will improve the functionality of my system. We went with solar primarily because we want to be environmentally conscious, but in the new world of climate change getting the battery backup right is also very important to us. Thank you!
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