Please help see if this system is okay

NilaNila Solar Expert Posts: 173 ✭✭
Hi All,

I was very actively designing & setting up systems 2 years ago but then due to other business stopped doing that.
Thank you BB especially for patiently helping me learn a lot of things.

Please help see if this system for my new home I am trying to put together is worthy and see if I am missing anything obvious.

It is true we used to have a lot of power failures previously but that is not the motivation anymore as the power is relatively better.

The scheduled shutdowns are like rarely straight 8 hours during day time that happens ONCE in two months
Unexpected shutdowns are like 1-2 hour per week but it is certainly much better than 6/hours a day that we had to deal with in past.

What I am trying to achieve here is
1. cut my power bills  (1000 KVH per Month & I am paying close to 110$ per month )
2. safeguard my important equipment from power failure & high voltages that DO happen at times.
3. Convenience (during those rare power shutdowns)

My load information is here:
https://docs.google.com/spreadsheets/d/1fjNop7NapHV6u2GSAYuymdftvIbZjNszNlRIU5uUiec/edit?usp=sharing

Important loads: 875 & Optional loads : 1150.watts

Optional Loads I am trying to get them into the inverter mostly to give them time to power off gracefully or to utlize the day time sun powering the loads directly. 

There are voltage spikes rarely on the grid I do not want them to kill all my electronics so having an Inverter cuts the grid when the voltage reaches a high limit.

I am trying to go with a PCU which includes MPPT charger / Inverter/ Charger in ONE box 

http://www.amazon.in/FlinInfini-2kW-24V-Smart-Hybrid-Inverter/dp/B01N6YQRDH/ref=sr_1_1?ie=UTF8&qid=1495909534&sr=8-1&keywords=ongrid+battery+backup
& there is a 5KW version with dual MPPT chargers.

These inverters do allow grid feeding which I can do as well if my local utiliy allows & allows using the solar power for the day time usage when battery is full.

Here is the specs: http://www.flinenergy.com/flininfinilite-specifications.html

Still divided on which one to choose.,

5KW 48V inverter costs me about 1550 USD &
2KW 24V costs about 850 USD.( if I only plan to use system for "Required Loads" )

I like to setup the systems so the inverter only performs at half the advertised values so there is no risk of damage & longer life.
I know they arent Schnieder but since I buy these Chinese rebranded inverters in India I get about 2 years warranty  & 3 years parts service after that.

Using a 6048 with 2x MPPT from Schnider Electric will set me back easily 3 times as the above due to their pricing in India.

Regarding the Panels I am planning to go with 250Watt (60 cells 37VOC) panels in 3 x 3 setup to begin with & add another 3 x 3 later on or another 2 parallel x 3 in series panels to add more power later on.

Regards to batteries ( we always use 12v ones )

An example: http://www.amazon.in/Exide-SOLAR-C10-TUBULAR-Battery/dp/B0190X28LQ/ref=sr_1_1?ie=UTF8&qid=1495910569&sr=8-1&keywords=c10+batteries

If I go with a 48V system, I am planning to use 8 x 150AH batteries that are rated c10 for solar usage ( is it important ? they seem to be touch costlier but have more warranty (5 yrs vs 2 or 3) in general ) , I would LOVE to go with 4 x 200 or 220AH but BB once told me about the ripple efforts.

If I go with a 24V system: I will use 4x 150 AH again the c10/solar batteries unless you advise against it.


Regards to wires: 

We plan to use the UV Rated 4Sq.MM cables for all panel connections & use 6 SQ.MM for connecting from the combiner box that parallels the strings to the inverter with a fuse.
Are 6 or 16Sq.MM Wires required for these high voltages? I know I used to use them with my old PWM setup with lower voltages.

Is there anything else I should think about?

If I end up going with the 24V system to ONLY power up my required loads, then how do I protect the optional loads , should I go for a whole home stabilizer or should I just use a power surge protector for TV/Projector/etc ? or add a cheap UPS ( under 200$ ) and Is there any issues If I use both the inverter + the power surge projector I heard that was a bad idea

Sorry again for all the tons of questions and any help is appreciated. I just forgot about all the solar & battery stuff for like 2 years and I got rusty with the details so ask me if there is any questions or if i missed any dteail.
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Comments

  • NilaNila Solar Expert Posts: 173 ✭✭
    I have an option to buy GEL batteries and generally is it better to get GEL or Flooded for solar projects?
  • BB.BB. Super Moderators, Administrators Posts: 32,005 admin
    edited May 2017 #3
    Fixed Typo Below (1,000 kWH). Thank you MVAS.

    Check the specifications... In the US, GEL batteries typically have a 5% (C/20) maximum rate of charge. If you charge faster than that, bubbles can form in the GEL and reduce battery capacity (the bubbles from gassing do not go away over time).

    Europe has (some?) GEL batteries that are rated for higher charging current. Yes, both GEL and AGM batteries can take pretty high charging current when discharged (say less than ~80% state of charge), but neither does well when hit with high charging currents when nearly full. They both gas (GEL can form the bubbles in the electrolyte), and both can overheat the catalyst (for those batteries with catalysts used to recombine the hydrogen+oxygen gasses back to water), and cause the batteries to vent--Losing electrolyte.

    Flooded cell tend to be more forgiving--Assuming you keep the water levels up (with distilled water--do not over fill) keep the tops/cables clean of electrolyte (monthly maintenance).

    Also, there are batteries designed for deep cycling (such as off grid solar power), and those batteries designed for float service (emergency backup power for UPS, telecom systems, and such). GEL tend to be designed for float service... AGM and flooded cell can be designed for either.

    In general, a full time off grid home will do very nicely (Lead Acid) batteries with a 10% to 13% rate of charge (from solar).

    You do not have a good match between the size of the AC inverter and the Battery bank... For a 48 vdc battery bank, the largest inverter you would want is 1,000 Watt per 100 AH @ 48 volt battery bank. If you have a 5kWatt inverter, you want a minimum of 500 AH @ 48 volts (if you wish to run the inverter near rated power). And similar for solar array--Around a maximum of 1,000 Watt array per 100 AH @ 48 volt battery bank works well.

    Remember that Power = Voltage * Current.... So a high voltage array has lower current for the same wattage (20 volts * 100 amps = 2,000 Watts; or 100 Volts * 20 amps = 2,000 Watts). For higher voltage systems, you want "better" insulation. In general, most "house type" AC wiring is rated a minimum of 600 VAC (in US) and possibly 1,000 VAC in other parts of the world (?).

    If you use "car or boat" wiring, the insulation may be rated 100 VAC or less.

    Your energy costs are pretty low ($110 USD per 1,000 kWH is only $0.11 per kWH--My electric service is 2-4x higher). You will not really save money on energy usage going with solar... Figure out how much energy you will use and divide it by the costs for batteries+solar+electronics (and replacement batteries every 5 years) for a 10 year system life... In general, it works out to something like $1,00 per kWH or more--Although, if you are really careful about costs and optimum power generation, perhaps you can get down towards $0.50 per kWH (of course--That is US pricing).

    So--Back to the old question of what you want to power... An 8 hour power outage and protect your computer/office equipment.... Making your own UPS system (AC mains -> AC Battery Charger -> Battery bank big enough for 8 hours of loads to 50% discharge -> AC inverter -> protected loads) will get you started. You can always add solar panels + solar charge controllers later. And you are protected against AC high/low voltage issues. AC Battery charger and/or Solar Power (as needed) to recharge the batteray bank and run your loads.

    You can also have an automatic transfer switch to bypass the "continuous conversion UPS" above and supply the AC power to the house when the power is up (this is more efficient vs going through an AC to DC to AC power conversion--But will switch some of your home circuits to the UPS output from AC mains when the power fails.

    You are getting ahead of yourself again... You need to focus on your loads first (and conservation) and then design a system that supports those loads/needs. For example, an 875 Watt load running 8 hours per day is a lot of energy (design for "worst case" 8 hour outage, primarily using battery bank as backup power system):
    • 875 Watts * 8 hours = 11,092 Watt*Hours per day ~ 11 kWH per day or 330 kWH per month
    • Battery: 11,092 WH per day * 1/0.85 AC inverter eff * 1/48 volt battery bank * 1 day of storage * 1/0.50 max discharge (longer battery life) = 544 AH @ 48 volt battery bank
    • AC Battery charger (5%-20% rate of charge typical, 10% rate of charge or more for full time off grid): 544 AH * 59 volts charging * 0.10 rate of charge = ~3,210 Watt AC battery charger output
    • AC Battery charger: (0.10 rate of charge * 544 AH battery bank) + (875 Watt AC load * 1/0.85 ac inverter eff * 1/52 volts float) = 75 Amp rated AC battery charger
    Then there is the solar charging system... First based on battery bank size + 24 hour per day load (i.e., charging+running loads at the same time). Assume 10% rate of charge but 5% to 13% rate of charge can be justified with grid connected charger (or even no solar):
    • Solar based on battery charging: 544 AH * 59 volts charging * 1/0.77 panel+controller deratings * 0.10 rate of charge = 4,168 Watt array (assuming full time off grid minimum)
    • Solar based on running load while charging: 875 Watt AC continuous load * 1/0.77 panel+solar charger derate * 1/0.85 AC inverter eff = 1,337 Watt array to run loads while charging
    • Total solar array based on battery bank size+full time load: 4,168 Watt (10% battery charging) + 1,337 Watt to run loads while charging = 5,505 nominal full time off grid array
    And then there is based on your amount of sun... Say Mumbai India (forgot if that is correct):
    http://www.solarelectricityhandbook.com/solar-irradiance.htm

    Mumbai
    Average Solar Insolation figures

    Measured in kWh/m2/day onto a solar panel set at a 71° angle from vertical:
    (For best year-round performance)
    Jan Feb Mar Apr May Jun
    6.54
     
    7.17
     
    7.42
     
    7.14
     
    6.69
     
    5.63
     
    Jul Aug Sep Oct Nov Dec
    4.94
     
    4.85
     
    5.69
     
    6.29
     
    6.46
     
    5.98
     
    Since this is a grid supplied system, no need for "over designing" the array for multi-day/week outages:
    • 875 Watt * 24 hours per day * 1/0.52 off grid system eff * 1/4.85 hours of sun per day (Aug "break even") = 8,327 Watt array for "full time" off grid power
    So--We have a problem here--If you only want to power your UPS during a maximum of 8 hour power failure--You have a small(er) battery bank (and array to run it).

    However, you wanted to run your 875 Watts full time (365 days a year) from solar, then you would need a "huge" array and and a 2-3x larger battery bank (because now, you have to supply the ~12 hours a night when "no sun" if you want full time off grid).
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • BB.BB. Super Moderators, Administrators Posts: 32,005 admin
    The above is probably a bit confusing--However that is because you kind of want to do two different things (emergency backup power vs full time off grid). That you have a Hybrid AC Inverter (both GT and Off Grid capable) can help (possibly) you save money by back driving the meter when the sun is up, and only run for 8 hours (maximum) during random power outages.

    Neither of my suggested designs are "optimized" in any way... Just some rules of thumbs to give you some ideas.

    For example, if your outages are 1-2 hours daily and 8 hours a couple times a year.. You could design the loads to take 75% of battery capacity during 8 hour discharge--You will plan on having the AC power back in time to recharge the battery bank immediately via the AC battery charger--That will keep the deep cycle batteries "happy" (don't have to wait for the sun the next day and clear weather).

    Your AC battery charger, you have AC mains 16-24 hours per day... With solar, you only have the sun around 6-9 hours per day--So it is more difficult to quickly recharge the battery bank (lead acid batteries really need ~8-12 hours of constant power to recharge from a deep cycle--So for off grid solar, we design a larger battery bank to keep the batteries from "deep cycling" every day).

    Anyway--I will stop here--Solar is totally optional at this point if you are designing for 2-8 hour outages--I would look at your AC Battery charger => battery bank => AC inverter design first--Then add solar+solar charger if you want to reduce some power costs.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • NilaNila Solar Expert Posts: 173 ✭✭
    Hi BB,

    Thank you immensely for all the time, Hugely appreciate the insights here. Hoping I am not making this painful for you by being a complete noob.

    I am from Madurai, India, Surprised these numbers are lower than Mumbai may be i am calculating it wrong, I used panels facing south, 
    Mumbai has a long monsoon season & Madurai is alway sunny & we dont have as much as rainfall or winter as mumbai.

    Madurai
    Average Solar Insolation figures

    Measured in kWh/m2/day onto a solar panel set at a 80° angle:
    JanFebMarAprMayJun
    5.21
     
    5.85
     
    6.11
     
    5.20
     
    5.55
     
    5.13
     
    JulAugSepOctNovDec
    4.89
     
    4.91
     
    5.09
     
    4.70
     
    4.45
     
    4.69

    I do not want to go for off-grid as I am always connected to the grid and I am happy to use the AC charging anytime. May be I was not clear in the earlier post. 

    My outages are like 1-2 hours weekly ( not even daily ) and worst case would be 2 hours daily if the power situation goes back to crap like 2 years ago - unlikely.
    8 Hours like four times a year.

    My Load is not "875Watts all the time" during the power outage, Here the long power outages only happen during day time as they called 'scheduled outages'  and during this time NONE of my lights will be on at all so I would be only using like 550 Watts.

    Always assume my battery bank will be full or at least more than 70% at any point in time & I would never have more than 8-10 hours grid power outage at max

    When I meant I want to save money I wanted to use the grid-feed feature available in the PCU / inverter to use the daytime solar panel wattage that would otherwise be unused. The power savings I would have by using 500 KWH vs 1000 KWH in my local GRID IS SO SIGNIFICANT that I can keep buying a battery every 3 months as I would get into a lower bracket tariff. 

    I also understand the solar is completely optional at this point I just wanted to utilize the Grid feed to reverse the meter ideally.

    So based on this information where I ONLY need this system to be my emergency backup + protect the loads + grid feed optionally does this change the battery bank requirements/etc?

    So my question to you would be.,

    " For a 48 vdc battery bank, the largest inverter you would want is 1,000 Watt per 100 AH @ 48 volt battery bank. If you have a 5kWatt inverter, you want a minimum of 500 AH @ 48 volts (if you wish to run the inverter near rated power). And similar for solar array--Around a maximum of 1,000 Watt array per 100 AH @ 48 volt battery bank works well."

    1. Do these rules change for off grid vs hybrid setup like mine? as I am almost certain I would never have to use the full or 50 percent of the battery except for 3-4 days a year?

    This all-in-one box has MPPT + AC Charger + Inverter all combined
    http://www.flinenergy.com/flininfinilite-specifications.html

    If I go with the 2KW inverter, I may have to setup my computers/projector to use another UPS that has a smaller battery just to shutdown gracefully.

    If I go with the 4KW+  I can connect all my critical devices to it, I do not plan to use my computers or TV or projector for 8 hours during the power outage, so the extra wattage available on this inverter/charge controller is ONLY to help with adding more panels in future 

    the only reason I was even talking about the 5KW version was that it had 2 MPPT charge controllers instead of 1,
    I am not sure how much of an Array it is possible with 1 MPPT operating at 60-115VDC (at 80 AMP )

    Not trusting the 80A number, assuming it does 60A how much of an array it is possible with 3 in the series setup? if its safe to do 4 strings then I may go with the 4KW one.

    2. What do you think is the best bet, 

    i.e the 2KW Inverter + 2KW Panels + 4 x 150 AH Batteries ( that gives 300 AH @ 24V) ?
    Then protect my other senitive loads with a seperate computer UPS

    or 

    4KW inverter + 2 or 3KW Panels + 4 x 200 AH Batteries ( that is 200 AH @ 48V) ?
    (assuming the total connected loads on entirety is only 2000 and we will shut down the computers/TV/Projectors as soon as there is a power cut ).
    I know the larger bank will surely help but I am reculant to buy 8 batteries as it adds to the cost significantly.

    3. Maximum battery charging from AC I can get is 60A on all these versions of PCU , Does this look alright or should I buy a seperate charger & use it?

    4. Regarding the GEL battery, it seems they sell a c10 solar gel battery here.
    http://www.amazon.in/Exide-Solatron-150AH-inverter-Maintenance/dp/B011Z1I97S/ref=sr_1_2?ie=UTF8&qid=1495998426&sr=8-2&keywords=gel+c10

    Should I go for it or should I go for the Tall Tubular batteries? which here people prefer & brand for all Solar applications. 







  • EstragonEstragon Registered Users Posts: 4,495 ✭✭✭✭✭
    The inverter/battery ratio depends somewhat on the nature of the loads. I have 7kw of inverter on [email protected] 48v battery, but that's really just to give me headroom in the unlikely event all my pumps try to start at once while I'm making toast. The load would't last long. Having a sustained load anywhere near capacity would be a bad idea.

    60a charging should be plenty for the size of bank you're considering.

    I wouldn't buy a gel or agm battery for this unless there was a compelling reason to. Flooded tend to be cheaper, and a bit more fixable is the charging regime isn't quite right.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • NilaNila Solar Expert Posts: 173 ✭✭
    @Estragon
    Got it, thank you for that,

    Gel vs tubular is decided. I will get Tubular.

    so all that's left for me to understand here is If  I should use the 2KW or 4KW setup & how much is the practical amount of panels I can add if i choose 4KW setup.
  • EstragonEstragon Registered Users Posts: 4,495 ✭✭✭✭✭
    I don't know anything about your computer setup, but my inclination would be to do a separate UPS for them, and size UPS batteries to cover some proportion of expected blackouts. The numbers would change based on application and how critical uptime was. The UPS and computers should be able to initiate a graceful shutdown automatically IMHO.

    Adding more panel if space and cost aren't issues isn't ever bad. The panels won't produce more than loads will take.

    Your situation is complicated by the grid-tie. You can calculate cost/benefits and IRR down to the penny all day long, but only on the basis of current grid costs and tie terms. For all I know, utilities could make a successful claim a few years from now that grid ties are causing outages and have them banned outright. Personally, I would size for loads to cover outages, and forget the grid tie part in costing. If you can sell some back for a while, bonus.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • solarkingsolarking Registered Users Posts: 67 ✭✭
    edited May 2017 #9
    Nila said:
    Hi All,

    I was very actively designing & setting up systems 2 years ago but then due to other business stopped doing that.
    Thank you BB especially for patiently helping me learn a lot of things.

    Please help see if this system for my new home I am trying to put together is worthy and see if I am missing anything obvious.

    It is true we used to have a lot of power failures previously but that is not the motivation anymore as the power is relatively better.

    The scheduled shutdowns are like rarely straight 8 hours during day time that happens ONCE in two months
    Unexpected shutdowns are like 1-2 hour per week but it is certainly much better than 6/hours a day that we had to deal with in past.

    What I am trying to achieve here is
    1. cut my power bills  (1000 KVH per Month & I am paying close to 110$ per month )
    2. safeguard my important equipment from power failure & high voltages that DO happen at times.
    3. Convenience (during those rare power shutdowns)

    My load information is here:
    https://docs.google.com/spreadsheets/d/1fjNop7NapHV6u2GSAYuymdftvIbZjNszNlRIU5uUiec/edit?usp=sharing

    Important loads: 875 & Optional loads : 1150.watts

    Optional Loads I am trying to get them into the inverter mostly to give them time to power off gracefully or to utlize the day time sun powering the loads directly. 

    There are voltage spikes rarely on the grid I do not want them to kill all my electronics so having an Inverter cuts the grid when the voltage reaches a high limit.

    I am trying to go with a PCU which includes MPPT charger / Inverter/ Charger in ONE box 

    http://www.amazon.in/FlinInfini-2kW-24V-Smart-Hybrid-Inverter/dp/B01N6YQRDH/ref=sr_1_1?ie=UTF8&qid=1495909534&sr=8-1&keywords=ongrid+battery+backup
    & there is a 5KW version with dual MPPT chargers.

    These inverters do allow grid feeding which I can do as well if my local utiliy allows & allows using the solar power for the day time usage when battery is full.

    Here is the specs: http://www.flinenergy.com/flininfinilite-specifications.html

    Still divided on which one to choose.,

    5KW 48V inverter costs me about 1550 USD &
    2KW 24V costs about 850 USD.( if I only plan to use system for "Required Loads" )

    I like to setup the systems so the inverter only performs at half the advertised values so there is no risk of damage & longer life.
    I know they arent Schnieder but since I buy these Chinese rebranded inverters in India I get about 2 years warranty  & 3 years parts service after that.

    Using a 6048 with 2x MPPT from Schnider Electric will set me back easily 3 times as the above due to their pricing in India.

    Regarding the Panels I am planning to go with 250Watt (60 cells 37VOC) panels in 3 x 3 setup to begin with & add another 3 x 3 later on or another 2 parallel x 3 in series panels to add more power later on.

    Regards to batteries ( we always use 12v ones )

    An example: http://www.amazon.in/Exide-SOLAR-C10-TUBULAR-Battery/dp/B0190X28LQ/ref=sr_1_1?ie=UTF8&qid=1495910569&sr=8-1&keywords=c10+batteries

    If I go with a 48V system, I am planning to use 8 x 150AH batteries that are rated c10 for solar usage ( is it important ? they seem to be touch costlier but have more warranty (5 yrs vs 2 or 3) in general ) , I would LOVE to go with 4 x 200 or 220AH but BB once told me about the ripple efforts.

    If I go with a 24V system: I will use 4x 150 AH again the c10/solar batteries unless you advise against it.


    Regards to wires: 

    We plan to use the UV Rated 4Sq.MM cables for all panel connections & use 6 SQ.MM for connecting from the combiner box that parallels the strings to the inverter with a fuse.
    Are 6 or 16Sq.MM Wires required for these high voltages? I know I used to use them with my old PWM setup with lower voltages.

    Is there anything else I should think about?

    If I end up going with the 24V system to ONLY power up my required loads, then how do I protect the optional loads , should I go for a whole home stabilizer or should I just use a power surge protector for TV/Projector/etc ? or add a cheap UPS ( under 200$ ) and Is there any issues If I use both the inverter + the power surge projector I heard that was a bad idea

    Sorry again for all the tons of questions and any help is appreciated. I just forgot about all the solar & battery stuff for like 2 years and I got rusty with the details so ask me if there is any questions or if i missed any dteail.
    If you want an economical option with limited features you can use any economial MPPT,  programmable timer and   regular inverter charger. I don't see any advantage in buying a hybrid inverter for $1550. Instead of spending too much on hybrid inverter you can add  an extra battery bank or more panels and you can go totally offgrid if you increase your battery bank.

    You can cut down your energy consumption by using  gorilla fan instead of 65 watt fan. Use LED tube instead of  fluroscent tube.
    go with a 48v system. The key to cut down the bill lies in the tarifif slab and picking the right sized array.

    Unless the grid power is erratic stabilizer is not required stabilizer wastes energy when used for whole house.

    Use exide c10 solar battery  or tall tubular battery. If you want your battery to last longer increase the size of your battery bank  and will last for more than 10 years if you don't discharge it below 80%. Gel battery sucks.

    I read your last post and  it seems you already own a  Schneider XW6048E why would you want to downgrade to some cheap chinese inverter.


  • NilaNila Solar Expert Posts: 173 ✭✭
    Hi SolarKing,

    4KW inverter is 1000$ and I don't own a Schnieder XW6048 but I was looking into buying one. I may well buy one for my office but not for the home.

    Every charge controller/Inverter imported from overseas are very expensive here so I would pay 130%+ the shipping / customs compared to costs in USA.

    All my lights are LED and I bought couple Philips hue ceiling leds which still consumes 40W at full brightness. I actually over-reported the load wattage in use so there is some leeway for me to over-provision the system and not under provision.

    I mean we may not really use all 7 65 watt fans at same time, more like 4 or 5 at sametime.
    I will look into the gorilla fan, first-time I heard it.

    Thanks for your advice on the whole house stabilizer., I am skipping it now that I have this 4KW inverter taking care of cutoff if the voltage goes over 280V

    Assuming I use just 4x 150AH battery for a total of 150AH @ 48V.
    Does this sound okay to use with this inverter ASSUMING

    Weekly we may discharge the battery up to 1-2 hours of 'upto' 1100Watt discharge (so like 2 KVH)
    Rare once in two months discharge of 8 hours (during day time when sun is there as backup ) of upto 5KVH discharge .

    This inverter allows setting the battery to shut down at 50% use so If it happens so be it , we are happy to have no power until the grid is back.

    Dos this sound okay or should I just in case buy 8 batteries to be on the 'safe' side? It would cost me another 1000 USD but if it is required I am okay to spend it than have 4 cooked batteries in 6months time.

    This inverter has this MPPT controller that operates in range from 60-115 (not sure what happens above 115) and its advertised Amperage is 80A, so please suggest how I can add panels assuming they are 250W or 300W each. 

    Since Solar is only optional I do not want to use the charge controller to its maximum effort and would like to keep it comfortable.

  • EstragonEstragon Registered Users Posts: 4,495 ✭✭✭✭✭
    Above 115v there's a decent chance the controller fails (and the high voltage is logged so your warranty dies too). That's a fairly low threshold, so you will need to be careful with panel voltages and temperature coefficient.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • solarkingsolarking Registered Users Posts: 67 ✭✭
    edited May 2017 #12
    Nila said:
    Hi SolarKing,

    4KW inverter is 1000$ and I don't own a Schnieder XW6048 but I was looking into buying one. I may well buy one for my office but not for the home.

    Every charge controller/Inverter imported from overseas are very expensive here so I would pay 130%+ the shipping / customs compared to costs in USA.

    All my lights are LED and I bought couple Philips hue ceiling leds which still consumes 40W at full brightness. I actually over-reported the load wattage in use so there is some leeway for me to over-provision the system and not under provision.

    I mean we may not really use all 7 65 watt fans at same time, more like 4 or 5 at sametime.
    I will look into the gorilla fan, first-time I heard it.

    Thanks for your advice on the whole house stabilizer., I am skipping it now that I have this 4KW inverter taking care of cutoff if the voltage goes over 280V

    Assuming I use just 4x 150AH battery for a total of 150AH @ 48V.
    Does this sound okay to use with this inverter ASSUMING

    Weekly we may discharge the battery up to 1-2 hours of 'upto' 1100Watt discharge (so like 2 KVH)
    Rare once in two months discharge of 8 hours (during day time when sun is there as backup ) of upto 5KVH discharge .

    This inverter allows setting the battery to shut down at 50% use so If it happens so be it , we are happy to have no power until the grid is back.

    Dos this sound okay or should I just in case buy 8 batteries to be on the 'safe' side? It would cost me another 1000 USD but if it is required I am okay to spend it than have 4 cooked batteries in 6months time.

    This inverter has this MPPT controller that operates in range from 60-115 (not sure what happens above 115) and its advertised Amperage is 80A, so please suggest how I can add panels assuming they are 250W or 300W each. 

    Since Solar is only optional I do not want to use the charge controller to its maximum effort and would like to keep it comfortable.

    If you have a 24v or 48v inverter  you can use systellar mppt with powersaver box. Unlike other Indian made mppt this has some user configurable options. You can equalize the battery and set float, bulk and absorption voltage. All inverters have the deep discharge protection inbuilt or configurable even your 4 kw inverter will have this feature. The only advantage I see in using the hybrid inverter is during overload scenario(It will  transfer the load to the grid ) and the other one is monitoring it via pc.

    4x150ah is more than enough if you don't intend to go offgrid and if there is no frequent grid failure . Your array must be large enough to run your load during day and keep your batteries full incase of grid failure during night. Theoretically you will be using your battery only during grid failure at night so 48v 150ah is ok. If you add another 4 batteries the depth of discharge will be  low and the batteries will last for more than 10 years. Exide solar is rated 5000 cycles at 80% DOD.

    What is you priority ? device protection and uninterupted power or utilizing solar or reducing electricity bill.

    If the panels are 60 cell 250watt then you can connect 3 in series and   parallel the series strings.
    If it is 72 cell connect 2 panels in series and parallel it.

  • EstragonEstragon Registered Users Posts: 4,495 ✭✭✭✭✭
    3x60cell in series is likely ok, but 115v doesn't give a ton of headroom for cold panels. 2x72 cell may not give enough voltage for mppt charging if hot.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • NilaNila Solar Expert Posts: 173 ✭✭
    solarking said:
    If you have a 24v or 48v inverter  you can use systellar mppt with powersaver box. Unlike other Indian made mppt this has some user configurable options. You can equalize the battery and set float, bulk and absorption voltage. All inverters have the deep discharge protection inbuilt or configurable even your 4 kw inverter will have this feature. The only advantage I see in using the hybrid inverter is during overload scenario(It will  transfer the load to the grid ) and the other one is monitoring it via pc.

    4x150ah is more than enough if you don't intend to go offgrid and if there is no frequent grid failure . Your array must be large enough to run your load during day and keep your batteries full incase of grid failure during night. Theoretically you will be using your battery only during grid failure at night so 48v 150ah is ok. If you add another 4 batteries the depth of discharge will be  low and the batteries will last for more than 10 years. Exide solar is rated 5000 cycles at 80% DOD.

    What is you priority ? device protection and uninterupted power or utilizing solar or reducing electricity bill.

    If the panels are 60 cell 250watt then you can connect 3 in series and   parallel the series strings.
    If it is 72 cell connect 2 panels in series and parallel it.

    Regarding my priority

    1. Device protection
    2. Uninterrupted power for the critical lighting & fans
    3. Battery's health
    4. reducing the electricity bill & utilizing the solar.

    The specs say 
    Maximum PV Array Open Circuit Voltage145 VDC
    so with 3x60 cells at typical 37.5 VOC, we won't be close to that.

    I am thinking about using 3 strings and paralleling them, to begin with then add another string later this year.

  • BB.BB. Super Moderators, Administrators Posts: 32,005 admin
    Nila,

    Have you picked the battery bank AH capacity and voltage? And the AC inverter wattage? Your AC loads (and how long to operate?). Will you have a back up genset (i.e., you run from battery for 2 hours and fire up the genset if outage goes longer than 2 hours)?

    I am a big believer in "balanced" system design. For 2 hours of backup power, you don't need a very big battery bank.

    However, a small flooded cell lead acid battery bank has a limited amount of current it can supply... I.e., a small bank with a "larger" AC inverter+loads may exceed the battery's current capacity.

    Similar for Solar Array--Too large of solar array (with small battery bank) can over voltage the battery bank and your connected DC devices.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • solarkingsolarking Registered Users Posts: 67 ✭✭
    edited May 2017 #16
    Nila said:Regarding my priority

    1. Device protection
    2. Uninterrupted power for the critical lighting & fans
    3. Battery's health
    4. reducing the electricity bill & utilizing the solar.

    The specs say 
    Maximum PV Array Open Circuit Voltage145 VDC
    so with 3x60 cells at typical 37.5 VOC, we won't be close to that.

    I am thinking about using 3 strings and paralleling them, to begin with then add another string later this year.

    If you have a kill a watt meter  note down the actual consumption during day time and night time. Take an average for 4 or 5 days and you will know what to do.

    The 3kw inverter that you have mentioned can be connected in parallel one as slave and other as master.  Even microtek has the same inverter but the information on their site is very limited.
  • NilaNila Solar Expert Posts: 173 ✭✭
    Hi BB,

    1. Battery voltage is 48V @150AH (4 12vs in series) 

    This one specifically : http://www.amazon.in/Exide-SOLAR-C10-TUBULAR-Battery/dp/B0190X28LQ/ref=sr_1_1?ie=UTF8&qid=1496142845&sr=8-1&keywords=c10+150ah+battery

    2. The inverter is 4KW ( though the MAXIMUM connected load is 2KW ) so you can consider this as a 2KW system.

    3.  The AC loads uses vary but about 600-1200 Watt  may run for 2 hours during the power failures during the night
    and during the day time the loads are even lower as we don't use the lights or computers and the sun is there as a backup.

    So my minimum usage is 0.6 KWH per hour during the day and maximum is 1.2 KWH per hour during the nights.

    I will notify my people to NOT use any high loads during the power off times and I can setup the inverter to shutdown when it reaches 50 or 40% battery level.

    battery
    qtyahv@80% efficency100 use @ 1.2KW50%100 use @ 0.8kw50%
    41501272005.764.82.47.23.6
    8150121440011.529.64.814.47.2

    This is my crappy way of quickly calculating the amount of hours backup I have, and for 4 batteries I get about 2.5 hours at night mode and 3.6 hours at day mode which is PERFECTLY fine as we never have long powerdowns during the night.

    8 batteries gives me even longer close to 5 hours at night and nearly 7 hours at day all at 50% DOD.

    Please let me know if I have any goof up on those numbers. 

    4. I do not have a backup Genset but I can buy one if needed as small ones under 3KVA doesn't cost huge but still just adding 4 more batteries may be cheaper.

    5. All my devices are AC and there is no directly connected loads to the battery , only via Inverter




  • NilaNila Solar Expert Posts: 173 ✭✭
    When they say a battery is c10 it allows both discharge & charging at the same rate? so how much wattage we should safely draw from the inverter without hurting the battery ? 
  • solarkingsolarking Registered Users Posts: 67 ✭✭
    Nila said:
    Hi BB,

    2. The inverter is 4KW ( though the MAXIMUM connected load is 2KW ) so you can consider this as a 2KW system.

    3.  The AC loads uses vary but about 600-1200 Watt  may run for 2 hours during the power failures during the night
    and during the day time the loads are even lower as we don't use the lights or computers and the sun is there as a backup.

    So my minimum usage is 0.6 KWH per hour during the day and maximum is 1.2 KWH per hour during the nights.

    I will notify my people to NOT use any high loads during the power off times and I can setup the inverter to shutdown when it reaches 50 or 40% battery level.

    battery







    qtyahv
    @80% efficency100 use @ 1.2KW50%100 use @ 0.8kw50%
    41501272005.764.82.47.23.6
    8150121440011.529.64.814.47.2

    This is my crappy way of quickly calculating the amount of hours backup I have, and for 4 batteries I get about 2.5 hours at night mode and 3.6 hours at day mode which is PERFECTLY fine as we never have long powerdowns during the night.

    8 batteries gives me even longer close to 5 hours at night and nearly 7 hours at day all at 50% DOD.

    Please let me know if I have any goof up on those numbers. 

    4. I do not have a backup Genset but I can buy one if needed as small ones under 3KVA doesn't cost huge but still just adding 4 more batteries may be cheaper.

    5. All my devices are AC and there is no directly connected loads to the battery , only via Inverter




    Are you using 2 x 4kw inverter right now?
    I can see you are using a 48v battery bank and 96v battery bank which means you have 2 inverters and you would like to upgrade to a hybrid inverter?

  • NilaNila Solar Expert Posts: 173 ✭✭
    This is a completely new setup and no I do not have 2 inverters.. when I meant 8 batteries it is 4 in series and 2 in parallel
  • solarkingsolarking Registered Users Posts: 67 ✭✭
    edited May 2017 #21
    Is flinslim selling inverter made by MPPsolar, Taiwan? There is a clone available and it is made in China.

    here is another hybrid inverter Bluesource Solar Inverter 5KVA/48V $705 which is cheaper than flinslim.




  • NilaNila Solar Expert Posts: 173 ✭✭
    They are seemingly buying from China , however they do provide support + the warranty ,

    705$ inverter works out to 1100 when it is in your hand if you add customs + shipping and has no real support /warranty.

    I considered buying it from AliExpress but then decided against as if I have to return ship due to any issues , the time / money lost is already more than the difference.


  • solarkingsolarking Registered Users Posts: 67 ✭✭
    edited May 2017 #23
    Nila said:
    They are seemingly buying from China , however they do provide support + the warranty ,

    705$ inverter works out to 1100 when it is in your hand if you add customs + shipping and has no real support /warranty.

    I considered buying it from AliExpress but then decided against as if I have to return ship due to any issues , the time / money lost is already more than the difference.


    $705(INR45,526.00) is not aliexpress price
    http://www.amazon.in/Solar-Inverter-5KVA-High-Frequency/dp/B072P1VL1W



  • BB.BB. Super Moderators, Administrators Posts: 32,005 admin
    Ok... a 150 AH @ 48 volts will "reliably" drive a 1,500 Watt AC load (flooded cell), and "reliably" accept a 1,500 Watt solar array input (any battery).
    • 150 AH * 48 volts * 0.50 max discharge * 0.85 ac inverter eff = ~6,120 Watt*Hours of "usable energy"
    • 6,120 WH / 1,500 Watt max continuous load = ~4.08 hours of operation (to 50% battery discharge or ~C/8 discharge rate)
    Note that your batteries (I think) are rated at C/10 discharge rate. A C/8 discharge rate is close enough for capacity estimate of bank under maximum load.

    Seems like a reasonable mix of system at the moment. Your 4 kWatt AC inverter is way larger than your battery bank can really supply (if you actually did pull upwards of 4kWatt).

    You do want to look at the Tare Load of the AC inverter (how much current/power it draws just being turned on and no loads). Large AC inverters can draw a significant amount of power (wasted power) from the battery bank because of lower efficiency at lower output power levels (upwards of 40 watts or more just to turn on the inverter?).

    If you are running the inverter 24x7 from battery bank (and AC battery charger) to protect your computer/loads against line surges--Those are more losses that you have to pay for/make up...:
    • (40 Watt ac inverter tare  + 1,200 Watt * 0.15 inverter losses + ~1,240 Watt * 0.20 battery charger/charging losses) * 24 hours per day = 11,232 WH per day just to run the "UPS" continuous conversion system (~468 Watts of "wasted power" 24 hours per day)
    • 11.2 kWH per day UPS continuous conversion losses * $0.11 USD per kWH = $1.23 per day "UPS" energy costs
    Large continuous conversion UPS setups can have significant costs/energy losses... The above is a "worst case" estimate--But does show it may save you some money if, for example, you only run your computer and router from the UPS 24x7 and only switch over lights/fan/other non-critical loads to UPS when the power actually fails (auto transfer relay).

    Also sizing your AC inverter closer to actual loads (your present battery bank design cannot supply a 4kWatt AC inverter with enough current for long term reliable operation) can save energy costs too (may be difficult to find a 1,500 Watt @ 48 volt AC inverter--You may have to go to a 24 or 12 volt battery bank--With those other issues of paralleling batteries).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • EstragonEstragon Registered Users Posts: 4,495 ✭✭✭✭✭
    FWIW, my panels are 250w in strings of 3, and voltage peaked at betwwen 110-111v the last few (cool) days here in NW Ontario Canada. That's not far off the 115v max you mentioned earlier. If you never see cool (currently ~10°C here) weather, maybe you'd be ok.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • NilaNila Solar Expert Posts: 173 ✭✭
    solarking said:
    Nila said:
    They are seemingly buying from China , however they do provide support + the warranty ,

    705$ inverter works out to 1100 when it is in your hand if you add customs + shipping and has no real support /warranty.

    I considered buying it from AliExpress but then decided against as if I have to return ship due to any issues , the time / money lost is already more than the difference.


    $705(INR45,526.00) is not aliexpress price
    http://www.amazon.in/Solar-Inverter-5KVA-High-Frequency/dp/B072P1VL1W



    Great find
    This one doesnt seem to have the grid-feed and has one MPPT whereas the one from the Flin had 2 and gridfeed.

    Not sure about warranty/support, but Flin was responsive to me over phone,etc.

    I m getting the 4KW one which has one MPPT and gridfeed.

  • NilaNila Solar Expert Posts: 173 ✭✭
    Estragon said:
    FWIW, my panels are 250w in strings of 3, and voltage peaked at betwwen 110-111v the last few (cool) days here in NW Ontario Canada. That's not far off the 115v max you mentioned earlier. If you never see cool (currently ~10°C here) weather, maybe you'd be ok.
    What if I told you I have never seen sub 20c EVER in Madurai during the day :) I wish weather gets colder here however it only gets hotter every year.
  • NilaNila Solar Expert Posts: 173 ✭✭
    edited May 2017 #28
    BB. said:
    Ok... a 150 AH @ 48 volts will "reliably" drive a 1,500 Watt AC load (flooded cell), and "reliably" accept a 1,500 Watt solar array input (any battery).
    • 150 AH * 48 volts * 0.50 max discharge * 0.85 ac inverter eff = ~6,120 Watt*Hours of "usable energy"
    • 6,120 WH / 1,500 Watt max continuous load = ~4.08 hours of operation (to 50% battery discharge or ~C/8 discharge rate)
    Note that your batteries (I think) are rated at C/10 discharge rate. A C/8 discharge rate is close enough for capacity estimate of bank under maximum load.

    Seems like a reasonable mix of system at the moment. Your 4 kWatt AC inverter is way larger than your battery bank can really supply (if you actually did pull upwards of 4kWatt).

    You do want to look at the Tare Load of the AC inverter (how much current/power it draws just being turned on and no loads). Large AC inverters can draw a significant amount of power (wasted power) from the battery bank because of lower efficiency at lower output power levels (upwards of 40 watts or more just to turn on the inverter?).

    If you are running the inverter 24x7 from battery bank (and AC battery charger) to protect your computer/loads against line surges--Those are more losses that you have to pay for/make up...:
    • (40 Watt ac inverter tare  + 1,200 Watt * 0.15 inverter losses + ~1,240 Watt * 0.20 battery charger/charging losses) * 24 hours per day = 11,232 WH per day just to run the "UPS" continuous conversion system (~468 Watts of "wasted power" 24 hours per day)
    • 11.2 kWH per day UPS continuous conversion losses * $0.11 USD per kWH = $1.23 per day "UPS" energy costs
    Large continuous conversion UPS setups can have significant costs/energy losses... The above is a "worst case" estimate--But does show it may save you some money if, for example, you only run your computer and router from the UPS 24x7 and only switch over lights/fan/other non-critical loads to UPS when the power actually fails (auto transfer relay).

    Also sizing your AC inverter closer to actual loads (your present battery bank design cannot supply a 4kWatt AC inverter with enough current for long term reliable operation) can save energy costs too (may be difficult to find a 1,500 Watt @ 48 volt AC inverter--You may have to go to a 24 or 12 volt battery bank--With those other issues of paralleling batteries).

    -Bill
    Hi Bill,

    Thank you for confirming so I would now start with 4 batteries instead of eight  and would it be a huge problem to have 3 strings (2250Watt) of solar panel? I can stick with just 1500 if thats a concern.

    I will look at the Tare load for sure when I have it with me next week probably.

    I won't be running the inverter 24/7 for any load.

    I would initially just use the inverter during the high voltage cutoff or grid failure times and may look into running the Inverter as a UPS only if the on-demand switchover causes any reboots to the computer or the Hue lighting, etc.

    I do not trust this Chinese inverter to work reliably for 24/7 operation like a Schnider electric one. so less work it does is generally better :).



  • NilaNila Solar Expert Posts: 173 ✭✭
    I m trying to have bit more panels that what I need just to utlize the grid-feed feature in the inverter but not at the expense of killing the battery.
  • NilaNila Solar Expert Posts: 173 ✭✭
    solarking said:
    Nila said:
    They are seemingly buying from China , however they do provide support + the warranty ,

    705$ inverter works out to 1100 when it is in your hand if you add customs + shipping and has no real support /warranty.

    I considered buying it from AliExpress but then decided against as if I have to return ship due to any issues , the time / money lost is already more than the difference.


    $705(INR45,526.00) is not aliexpress price
    http://www.amazon.in/Solar-Inverter-5KVA-High-Frequency/dp/B072P1VL1W



    @Solarking do you know where can I get some decent combiner box with the DC Fuse so I can parallel the strings from panel?
  • BB.BB. Super Moderators, Administrators Posts: 32,005 admin
    The maximum solar panel, to a degree, depends on how the solar charge controller behaves.

    There have been instances of where MPPT type charge controllers do a "current sweep" of the array--Dumping all of the maximum available current from the array into the battery bank during the sweep. If the battery bank is near 100% full, the bank does not have much ability to "sink" that extra current if it exceeds (roughly) 1,000 Watts per 100 AH of battery capacity @ 48 volts.

    If your MPPT controller does not do a "sweep and dump" into a full battery bank, it may be OK to have a larger array--But you will have to verify the proper operation and watch for battery bank overvoltage (Schneider has reported battery bus failure >~72 VDC with (some?) of their 48 VDC inverters with oversized arrays).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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