Partial off grid battery backup system with Sunny boy 5000TL-US?

Core2QuadCore2Quad Registered Users Posts: 6
Hi Guys,

So I'm having solar installed on my house soon (I'm in California and our city just offered a $1 per watt incentive which I took advantage of).

Anyways, I originally liked microinverters, but because those do not work when the grid fails, I opted to go with the Sunny Boy 5000TL-US with built in 1500W secure power supply. I'm having a 5.5 DC Kw's installed, and what I'd like to do is basically make a small battery backup system, so if/when the grid fails I can use that 1500W AC Plug during daylight hours to charge 2-4 Deep cycle batteries. Then I will either run a pure sine-wave inverter with an extension cords, or may install a smaller sub panel in order to power several in house circuits. Basically all I'm trying to do is keep the fridge running and possibly a few other things like a few lamps.

So what kind of setup would you guys recommend? I was planning on using 2-4 deep cycle batteries + a AC powered battery tender to float the batteries and keep them charged / maintained. Then if the grid does fail, I would manually plut in a larger higher current battery charger to charge the batteries during the day. Maybe something capable of drawing about 10-15A AC. I am not sure though what kind of battery tender to use, and also what kind of batteries would be best. I was originally looking at possibly 4 Trojan T-105 RE's but they seem a little expensive around here, like $190 + $25 core.

Another battery I looked at was a Rolls / Surrette S-460 for $310 + core or a S-550 for $340 + core. These seem to be a better value than the Trojan's unless I can get those cheaper somehow.

So my questions are as follows:

1) Any battery tender recommendations?
2) Any battery charger recommendations?
3) What kind of deep cycle batteries would you recommend? I'm looking at around 3-5Kwhrs worth of batteries. Maybe 2 to 4, 6v batteries.
4) Any inverter recommendations? I'd like something around 1500-2000W, for preferbly ~$500. Must be pure sine wave.

I'm trying to keep the total cost to around $1000-1500 for this small partial battery backup project.

Thanks in advance for any recommendations!

Comments

  • Blackcherry04Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    Re: Partial off grid battery backup system with Sunny boy 5000TL-US?

    The one question I'd ask myself, Is this for a short grid outage or for a genuine situation where the panels could be compromised and there are no panels for the 1,500 watts. In California Ice and Snow may not be a problem in some places, but there are storms and weather that can limit their power or they produce nothing for days even without any damage. The 1,500 watts is UP TO , but there is no way to know what they might produce.

    14 days of almost no production. Here you have to have a small Generator and a supply of gas and pray.

    Attachment not found.
  • solarixsolarix Solar Expert Posts: 713 ✭✭
    Re: Partial off grid battery backup system with Sunny boy 5000TL-US?

    Not a bad idea. SunnyBoy TL inverters are my choice #1 because of the built in secure power feature. Grid failure is rare enough to make it hard to justify any additional expense, but when the TL can provide backup power to critical loads, why not? Refrigerators will act as their own battery - power it during the day off your TL and let it coast through he night by not opening it. Also Xantrex makes a nice, neat 1500W backup battery system called the PowerHub1800 for under $700, batteries not included.
  • BB.BB. Super Moderators, Administrators Posts: 29,634 admin
    Re: Partial off grid battery backup system with Sunny boy 5000TL-US?

    Using an AC battery charger connected to the 1,500 Watt 120 VAC output of the inverter is a bit of issue.

    Basically, the 1,500 Watts is supplied by the solar array--which has no storage or surge capability. With a 5,000 Watt array, you certainly have a lot of surge current available--Has anyone seen what the 120 VAC outlet is rated for as Surge Current output?

    Many of the common battery chargers can have significant surge current (2x or more of rated input current). So--you sort of run into a situation where you may have problems "starting" a larger battery charger (enough sun to for surge and charging current). So--The battery charger does not really do anything until the minimum amount of sun/energy is available.

    Which--Makes the AC charging less efficient than a set of panels + solar charge controller--As soon as there is any direct sun available (morning/evening), the charge controller starts sending current/power to the battery bank for charging. Gives you more hours of sun per day and more hours of charging current (lead acid batteries are stressed by high current charging with only a few hours of charging current per day). Also, if I recall correctly, you have to "manually" start the SMA backup AC output--Sort of pain.

    My guess--You can use a Iota ~45 amp 12 VDC charger (get the IQ4 optional module--Handy for grid connected power) on the 1,500 Watt SMA output (assuming the SMA can supply initial surge current). An AC battery charger in the 10% to 20% rate of charge range is usually a good fit. Or:

    45 amps * 1/0.10 = 450 AH @ 12 volt battery bank
    45 amps * 1/0.20 = 225 AH @ 12 volt battery bank

    Perhaps somebody here has experience with the SMA 120 VAC backup power output and using an AC battery charger (like the Iota)--It is all pretty new and I have not heard of anybody using the backup AC outlet yet (on the forum here).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Core2QuadCore2Quad Registered Users Posts: 6
    Re: Partial off grid battery backup system with Sunny boy 5000TL-US?
    The one question I'd ask myself, Is this for a short grid outage or for a genuine situation where the panels could be compromised and there are no panels for the 1,500 watts. In California Ice and Snow may not be a problem in some places, but there are storms and weather that can limit their power or they produce nothing for days even without any damage. The 1,500 watts is UP TO , but there is no way to know what they might produce.

    14 days of almost no production. Here you have to have a small Generator and a supply of gas and pray.

    Attachment not found.

    No severe weather around here, and snow is quire rare. Might get a few inches every few years. The storage is for a situation that could take out grid power for up to an extended period of time or even if it just happens to go out for a few minutes or hours one day (so far we've only had one outage in the last 5 years which lasted 4-5 hours due to a drunk driver taking out some transmission equipment). I know solar is slightly unknown with regards to the weather, but I believe we should at least get a little bit of power pretty much everyday. I live in the 2nd sunniest city in the United States.
    solarix wrote: »
    Not a bad idea. SunnyBoy TL inverters are my choice #1 because of the built in secure power feature. Grid failure is rare enough to make it hard to justify any additional expense, but when the TL can provide backup power to critical loads, why not? Refrigerators will act as their own battery - power it during the day off your TL and let it coast through he night by not opening it. Also Xantrex makes a nice, neat 1500W backup battery system called the PowerHub1800 for under $700, batteries not included.

    The power hub 1800 looks interesting, however the reviews on amazon and google do not seem very favorable: http://www.amazon.com/Xantrex-PH1800-GFP-PH-1800-GFP-PowerHub/dp/B000NONM94#customerReviews

    https://www.google.com/shopping/product/15781602263200069449?q=PowerHub1800&espv=2&bav=on.2,or.r_cp.r_qf.&ion=1&biw=1280&bih=743&bvm=pv.xjs.s.en_US.jy1SGYsq9dM.O&tch=1&ech=1&psi=RobxU-ykG4b4oASLxYCgBA.1408337623161.3&prds=hsec:reviews&ei=2IbxU6_RFsehogSJ1YCQDQ&ved=0CKsFEI0zMAs

    BB. wrote: »
    Using an AC battery charger connected to the 1,500 Watt 120 VAC output of the inverter is a bit of issue.

    Basically, the 1,500 Watts is supplied by the solar array--which has no storage or surge capability. With a 5,000 Watt array, you certainly have a lot of surge current available--Has anyone seen what the 120 VAC outlet is rated for as Surge Current output?

    Many of the common battery chargers can have significant surge current (2x or more of rated input current). So--you sort of run into a situation where you may have problems "starting" a larger battery charger (enough sun to for surge and charging current). So--The battery charger does not really do anything until the minimum amount of sun/energy is available.

    Which--Makes the AC charging less efficient than a set of panels + solar charge controller--As soon as there is any direct sun available (morning/evening), the charge controller starts sending current/power to the battery bank for charging. Gives you more hours of sun per day and more hours of charging current (lead acid batteries are stressed by high current charging with only a few hours of charging current per day). Also, if I recall correctly, you have to "manually" start the SMA backup AC output--Sort of pain.

    My guess--You can use a Iota ~45 amp 12 VDC charger (get the IQ4 optional module--Handy for grid connected power) on the 1,500 Watt SMA output (assuming the SMA can supply initial surge current). An AC battery charger in the 10% to 20% rate of charge range is usually a good fit. Or:

    45 amps * 1/0.10 = 450 AH @ 12 volt battery bank
    45 amps * 1/0.20 = 225 AH @ 12 volt battery bank

    Perhaps somebody here has experience with the SMA 120 VAC backup power output and using an AC battery charger (like the Iota)--It is all pretty new and I have not heard of anybody using the backup AC outlet yet (on the forum here).

    -Bill

    If "surge current" is an issue, I'd like to opt for a charger with multiple current settings. So lets say I can soft start the charging at 2A AC current, then kick it up a notch to 10-12A or so. I appreciate the feedback so far guys, please post some hardware recommendations such as chargers, batteries, inverters etc.
  • BB.BB. Super Moderators, Administrators Posts: 29,634 admin
    Re: Partial off grid battery backup system with Sunny boy 5000TL-US?

    If this is your only charger--You really should be looking at 10% rate of charge minimum (5% is possible too--But not great for off grid charging--very slow).

    A 2-10 amp charger is going to be very slow of any sort of larger storage battery setup.

    A 2-4x golf cart battery setup is going to need closer to 20-45 amps of charging current.

    If you want a sophisticated Off Grid system--Look at an inverter+charger. Many of them have a programmable input current that does a better job of managing current from an AC generator (or your SMA's AC output).

    Demonstration of Generator Support


    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Core2QuadCore2Quad Registered Users Posts: 6
    Re: Partial off grid battery backup system with Sunny boy 5000TL-US?

    Any more suggestions?
  • stephendvstephendv Solar Expert Posts: 1,571 ✭✭
    Re: Partial off grid battery backup system with Sunny boy 5000TL-US?

    How about splitting the solar array, half to a smaller sunny boy with that backup feature and the other half to an MPPT controller and outback G series inverter/charger. The outback will do the charging, inverting and selling to the grid- and of course then it would work very well off-grid too.
    Then you could distribute your house loads across the two, so that essential items run off the outback and the non-essentials run off the SMA backup power.

    Might stretch the budget a bit though...

    For bonus points there's also the option of AC coupling the sunny boy to the output of the outback so that you have the full power of the array available during outages, see: http://www.solarpowerworldonline.com/2013/08/dont-despair-ac-coupling-can-alleviate-your-solar-storage-challenges/
  • Core2QuadCore2Quad Registered Users Posts: 6
    Re: Partial off grid battery backup system with Sunny boy 5000TL-US?
    stephendv wrote: »
    How about splitting the solar array, half to a smaller sunny boy with that backup feature and the other half to an MPPT controller and outback G series inverter/charger. The outback will do the charging, inverting and selling to the grid- and of course then it would work very well off-grid too.
    Then you could distribute your house loads across the two, so that essential items run off the outback and the non-essentials run off the SMA backup power.

    Might stretch the budget a bit though...

    For bonus points there's also the option of AC coupling the sunny boy to the output of the outback so that you have the full power of the array available during outages, see: http://www.solarpowerworldonline.com/2013/08/dont-despair-ac-coupling-can-alleviate-your-solar-storage-challenges/

    I discussed that with my solar installer and it would add considerable more cost and complexity. The contract has already been signed for the system. The battery bank setup is up to me.

    The installer did mention AC coupling to me, but yea it doesn't sound like it would be cheap... So I'm just opting to do the simple battery bank / inverter thing myself.
  • bill von novakbill von novak Solar Expert Posts: 863 ✭✭✭✭
    Re: Partial off grid battery backup system with Sunny boy 5000TL-US?
    Core2Quad wrote: »
    1) Any battery tender recommendations?
    2) Any battery charger recommendations?
    3) What kind of deep cycle batteries would you recommend? I'm looking at around 3-5Kwhrs worth of batteries. Maybe 2 to 4, 6v batteries.
    4) Any inverter recommendations? I'd like something around 1500-2000W, for preferbly ~$500. Must be pure sine wave.
    I'd skip all that and just get a good 1500 watt sine wave UPS. They're cheap, and are intended for precisely what you're looking for (very occasional operation, floating a battery bank.) Plug it into a regular outlet, then during the outage switch to the "secure" plug. If you want more storage add to their battery.
  • Alaska ManAlaska Man Solar Expert Posts: 252 ✭✭
    Re: Partial off grid battery backup system with Sunny boy 5000TL-US?

    "So I'm just opting to do the simple battery bank / inverter thing myself".

    The simplest and least expensive would be to buy a generator and charge with that. If you only have an outage once or twice a decade and only for a few hours, a full solar/battery backup........... well, I couldn't justify spending that kind of scratch on it.
  • MarkCMarkC Solar Expert Posts: 182 ✭✭✭
    Re: Partial off grid battery backup system with Sunny boy 5000TL-US?

    Just joined the Forum as this one seems the most informative when searching for just about any PV solar system information.

    I recently finished installing an "on-grid" Sunny Boy 4000 TL US with approx 4000 rated watts of SolarWorld 280 panels. I have been "experimenting" with the using the SPS to power up a Golf Cart charger. I have a Club Car with 48 volt/155 AH set of Interstate batteries. It came with the OEM charger that is controlled by the Cart computer. The SPS has had no problem starting and powering the charger under full 3400 watts (about the best I've seen to date) down to 2600 watts "early day" sun. The SB shows 700+ watts when full charging amps of 13 at the start of the charge. I plan on continuing tests on various conditions of partial sun, early morning/late evening to determine about where the SPS will not start and/or cycle too much to be usable. Core2Quad - I'll keep you informed of any useful testing results.

    Eventually, I plan on a "hybrid" off-grid system that will split my panels to feed the SPS for Cart battery charging (and some other Li-ion batteries), with the remaining panels fed to a Midnite Kid CC. The Kid will charge a set of 4 new Golf Cart batteries that will eventually fed an inverter for limited off-grid power. This "hybrid" will only be used during an extended outage - which WILL OCCUR during the next hurricane here in Texas Gulf Coast!! This installation is in a remote location with power coming from a green-friendly co-op that has many miles of transmission lines thru heavily forested areas. I'm at the end of that transmission system.

    Any advice on the design of the "hybrid" is really appreciated.
    Mark
    3850 watts - 14 - 275SW SolarWorld Panels, 4000 TL-US SMA Sunny Boy Grid tied inverter.  2760 Watts - 8 - 345XL Solar World Panels, 3000 TL-US SMA Sunny Boy GT inverter.   3000 watts SMA/SPS power.  PV "switchable" to MidNite Classic 250ks based charging of Golf cart + spare battery array of 8 - 155 AH 12V Trojans with an  APC SMT3000 - 48 volt DC=>120 Volt AC inverter for emergency off-grid.   Also, "PriUPS" backup generator with APC SURT6000/SURT003  => 192 volt DC/240 volt split phase AC inverter.  
  • Core2QuadCore2Quad Registered Users Posts: 6
    Re: Partial off grid battery backup system with Sunny boy 5000TL-US?
    MarkC wrote: »
    Just joined the Forum as this one seems the most informative when searching for just about any PV solar system information.

    I recently finished installing an "on-grid" Sunny Boy 4000 TL US with approx 4000 rated watts of SolarWorld 280 panels. I have been "experimenting" with the using the SPS to power up a Golf Cart charger. I have a Club Car with 48 volt/155 AH set of Interstate batteries. It came with the OEM charger that is controlled by the Cart computer. The SPS has had no problem starting and powering the charger under full 3400 watts (about the best I've seen to date) down to 2600 watts "early day" sun. The SB shows 700+ watts when full charging amps of 13 at the start of the charge. I plan on continuing tests on various conditions of partial sun, early morning/late evening to determine about where the SPS will not start and/or cycle too much to be usable. Core2Quad - I'll keep you informed of any useful testing results.

    Eventually, I plan on a "hybrid" off-grid system that will split my panels to feed the SPS for Cart battery charging (and some other Li-ion batteries), with the remaining panels fed to a Midnite Kid CC. The Kid will charge a set of 4 new Golf Cart batteries that will eventually fed an inverter for limited off-grid power. This "hybrid" will only be used during an extended outage - which WILL OCCUR during the next hurricane here in Texas Gulf Coast!! This installation is in a remote location with power coming from a green-friendly co-op that has many miles of transmission lines thru heavily forested areas. I'm at the end of that transmission system.

    Any advice on the design of the "hybrid" is really appreciated.
    Mark

    Very cool, thanks for joining the forums and letting me know that you have a 4000 TL US. I'm also going with solarworld panels. My installer is still waiting on all the permits and stuff before he will begin. I expect he will begin installing in about 1 month. I've already been approved for the local city $1 per AC watt rebate, which is about $4500 in my case. So that makes the total system about 45% paid for.

    As of right now, my latest idea is to perhaps use a Xantrex TrueCharge 2 (40A charger). Along with either 4x 6v golf cart batteries or 2x L16 sweeper/solar batteries. I've looked at inverters and I can't seem to find any pure sine wave inverter above 1000W that seems to be of good quality and a reputable brand. The Xantrex 1000W Prowatt SW 1000 seems like a solid inverter and has very good reviews on Amazon. The 2000W however has much poorer reviews, and sounds like its no longer being made. So I may end up going with that Xantrex 1Kw inverter, and a cheap but decent modified sine wave inverter in the 3Kw range for larger things I may need / want to power.

    MarkC if you can, can you try to test the surge capability of the SPS? If you have say clamp meter you can try to measure the surge of something that may use a lot of power (an air compressor for example). Also is it able to handle say a 1500W heatgun/heater/hair dryer? And also what happens if you try to lightly overload it for a longer period of time like say 5 minutes (e.g. a 1500W heater/heatgun + 500W halogen worklight).

    Also since you are also looking for a "hybrid system." What are your requirements... e.g. budget, inverter size, battery bank size.

    Alaska Man wrote: »
    "So I'm just opting to do the simple battery bank / inverter thing myself".

    The simplest and least expensive would be to buy a generator and charge with that. If you only have an outage once or twice a decade and only for a few hours, a full solar/battery backup........... well, I couldn't justify spending that kind of scratch on it.

    A generator is not an option for what I want it for. This for both the occasional utility outage, but is also more of a "prepper" type application, where gas could not be available for months or even a couple years etc...

    I'd skip all that and just get a good 1500 watt sine wave UPS. They're cheap, and are intended for precisely what you're looking for (very occasional operation, floating a battery bank.) Plug it into a regular outlet, then during the outage switch to the "secure" plug. If you want more storage add to their battery.

    I can't seem to find any decent pure sine wave UPS's with more than 200-300 or so Whrs worth of batteries. Secondly, I'm unsure if those UPS's are designed for continuous use. I'd want something that could say run a 750W appliance for 1-2 hours straight if needed.
  • MarkCMarkC Solar Expert Posts: 182 ✭✭✭
    Re: Partial off grid battery backup system with Sunny boy 5000TL-US?

    Core2Quad;
    Couple of thoughts as I am a little ahead of you (in time at least!).
    1. You might want your installer to have all the connections ready for the panel "split". This is because most small charge controllers are limited in series/parallel set up capabilities compared to the Sunny Boy inverters and you MIGHT need to rewire later. Better to consider having all the wiring/connectors available for an easy conversion in time of trouble (at night possibly for safety?).
    2. Look into the Kid - it seemed unusual in it's PV/battery voltages (and other) capabilities - for it's size and cost. Midnite is US company and very knowledgeable. Using the 48 volt DC option, it will provide over 1500 watts of charge using 6 of the 280 w mono panels
    3. The only full featured (off-grid) inverters that will do everything that I want (split phase and future generator addition) are currently the Apollo Solar line and the Magnum line of split phase inverters. There are others (hybrid type, Xantrex, Outback - $$$), but these two are US and the staff are extremely knowledgeable about incorporation of a generator (I have a 6500 watt, electric start, split phase generator). NOTE - in Texas, at least one Air Conditioner is needed for survival! Of course, fuel rationing is mandatory depending on expected outages - so ease of generator start-up is essential. Of course, this may not be part of your requirement, but split phase is an absolute for me due to a 240 V well pump for water supply - in the "prepper" phase!
    4. With an 48 volt/155 AH golf cart being a given, having a spare set is really nice and gives me fair amount of storage. I plan on using a 60 amp Anderson quick connect system to tie-in the Cart battery bank during usage only (opinions seem to verify this as OK) - NOTE, be careful about breaker/fuse protection. In a "prepper" phase, the SB will charge the Cart and Kid will charge the spare set.

    Your ideas for testing are great - It could be a while until I can do more serious testing, but I'll try some of your suggestions and get back. I don't have the right clamp amp meter, but the SB does show total watts being sent to the SPS - I'll record AC voltages at the plug also.

    BTW, I have considered the UPS route, but came to conclusion that having another set of batteries to help charge a real set of batteries was either much too expensive for a "real" UPS, or that a cheap one will not do the job - and what if those batteries go out? If my Cart charger works with the SPS, I don't need it anyway. The big question is how many panels do I need to ensure the SPS will start and keep the Cart charger on-line on partially sunny days??? If my calcs are OK, I'll need at least 6 hours of continuous day charging for every night of full usage.

    Anyway, it's been a hoot so far - and has been much more theory than application. At some point, I got to plunk down the cash however! The inverter and batteries are not cheap!
    3850 watts - 14 - 275SW SolarWorld Panels, 4000 TL-US SMA Sunny Boy Grid tied inverter.  2760 Watts - 8 - 345XL Solar World Panels, 3000 TL-US SMA Sunny Boy GT inverter.   3000 watts SMA/SPS power.  PV "switchable" to MidNite Classic 250ks based charging of Golf cart + spare battery array of 8 - 155 AH 12V Trojans with an  APC SMT3000 - 48 volt DC=>120 Volt AC inverter for emergency off-grid.   Also, "PriUPS" backup generator with APC SURT6000/SURT003  => 192 volt DC/240 volt split phase AC inverter.  
  • MarkCMarkC Solar Expert Posts: 182 ✭✭✭
    Re: Partial off grid battery backup system with Sunny boy 5000TL-US?

    Additional Sunny Boy 4000 TL-US inverter data;
    48 volt Club Car charger test;
    Charger consistently starts on the SPS and registers about 13 DC amps and about 700+ watts on the inverter screen. Normally the DC amps will drop to 8 amps or less fairly quickly depending upon state of charge of the batteries
    Testing on a rainy day, the total wattage of my panel system was about 670 watts on the inverter screen (grid-tied) and was slowly rising as the clouds were moving out. I shut off the grid disconnect and started the SPS at this wattage. The charger kicked in at about 700 watts registering on the "stand-alone ops" status - with a reading of 13 DC amps, quickly settling at 11 amps on the charger. The inverter continued to show 700 watts and started cutting back as the DC amps started coming down. When I shut down the SPS and reconnected the inverter to the grid, the wattage reading on the inverter screen was around 800 watts. This indicates to me that the SPS can start a golf cart type charger with little "surge" capacity required and can consistently charge the batteries with anything above 800 watts available from the PV panels. This would of course vary with the type of charger, but again appears that the computer controlled type charger of the typical club car will work very well with the Sunny Boy SPS.

    Testing the SPS with a 1850 watt rated hair dyer;
    Testing in bright sun with 3000+ watts on the inverter screen, with little or no cloud cover, I disconnected the grid and turned on the SPS. I then plugged in the hair dryer with the following results;
    Hair dryer setting on "cool" - fan only - wattage on "stand-alone ops" was 250
    Hair dryer setting on "warm" - wattage on "stand-alone ops" was 950
    Hair dryer setting on "hot" - both the hair dryer and the SPS would shut down - no wattage reading.

    I'll likely continue testing to determine the maximum "stand alone ops" I can get by using a combination of the hair dryer on the cool and warm settings with the golf cart charger - more later!
    3850 watts - 14 - 275SW SolarWorld Panels, 4000 TL-US SMA Sunny Boy Grid tied inverter.  2760 Watts - 8 - 345XL Solar World Panels, 3000 TL-US SMA Sunny Boy GT inverter.   3000 watts SMA/SPS power.  PV "switchable" to MidNite Classic 250ks based charging of Golf cart + spare battery array of 8 - 155 AH 12V Trojans with an  APC SMT3000 - 48 volt DC=>120 Volt AC inverter for emergency off-grid.   Also, "PriUPS" backup generator with APC SURT6000/SURT003  => 192 volt DC/240 volt split phase AC inverter.  
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