New Member from India! (UPS/Solar System Questions)

ksbalajiksbalaji Registered Users Posts: 7
I live in Chennai India (which place is almost straight down the floor and through the globe for most of you people living in US). I am facinated by Solar electric energy prospects (though per watt cost seems very prohibitive in this part of the world). Cost per watt of conventional electricity for homes is about $0.05 here! Is it not cheap? However, power shut downs are regular here (about a few hours daily!) . When I wanted to try building my own solar power system as a fall-back, I naturally sought help from internet and as a pleasant surprise found this nice set of people sharing information. Can someone guide me regarding building my own solar power system? A modest 1k Watt output is my dream. I do need information on reliable, economical solar cell suppliers who could deliver and service at Chennai, India. I feel all other materials like cables, panel frame, inverter, batteries, can be purchased/made locally. I seek help from you please!

Comments

  • BB.BB. Super Moderators, Administrators Posts: 30,483 admin
    Re: New Member from India!

    ksbalaji, welcome to the forum!

    Regarding your system supplier questions--obviously, we do not have a lot of members from India--but hopefully, the couple that we have can help you identify possible suppliers for you.

    Regarding the system design itself--first you need to identify your power needs. Basically peak power (maximum power in Watts or kilo-Watts) and how much power you use/need per day (or power failure period) in kWattHours.

    What you mentioned was peak power--1kW or 1,000 watts. That is a reasonable amount of power -- not a very large inverter (I assume you are looking for ~230 VAC at 50 Hz?) is required for that.

    However, you need to know the "peak" and average peak power. Motors may require 5x as much power to start as to run--for example.

    Next, there are several major classes of inverter... One is the Modified Sine/Square Wave type inverter (MSW). In general--this inverter works OK for many people--but some equipment (typically small electronics/wall mount transformers and some motors like in refrigerators) can overheat and fail (in minutes to weeks/months).

    That leads to the next type of inverter--True Sine Wave (TSW) inverter. This type if inverter output pretty near the normal sine wave that you will find from your utility power. Highly recommended you use a TSW inverter to run your home/shop equipment.

    However, a TSW inverter is many times more expensive than a MSW inverter (in the US, you can get a 300 watt MSW inverter for $20-$30; a similar TSW inverter may cost your $200+).

    The next question is how much power do you use over time.

    While a 1 kW inverter "sounds small"--it depends on your average power usage as to sizing the rest of your system... 1 kW for 10 minutes per day to pump water is:

    1,000 watts * 10min/60min per hour = 167 Watt*Hours or 0.167 kWatt*hours

    Or, 1,000 watts 24 hours per day (say some computer servers):

    1,000 watts * 24 hours per day = 24,000 Watt*Hours or 24kWhrs per day.

    The first system may need a 60 watt solar panel to supply your needs and the second system would need over 8,000 watts of solar panels to run your computers 24 hours per day.

    And, of course, the number/size of battery bank to run these loads will similarly be affected too (very small bank or very large bank).

    Next--your power needs are really a few hours per day when your utility power has failed.

    In many parts of the world (including member here), they essentially build their systems like a large UPS device (Uninterruptable Power Supply). Because utility power is so cheap and available the other 20 hours per day (normally)--they build a battery/inverter system with an AC charger instead of solar panels. Meets their needs (backup power for utility failure) and charging with cheap power from the utility.

    You can build the "whole house UPS" system as above--and always add solar panels+solar charge controller later as your finances allow.

    The few issues with the above UPS system... Power tends not to be cheap from these systems--very roughly in the US, parts and replacement batteries (every 3-10 years, assume 20 year life for rest of components) will run the costs around ~$0.45 per kWhr (not even including the $0.05 per kWhr cost of utility power)--but it is better than the $1.00-$2.00 per kWhr (in the US) that a solar based Off-Grid system would cost you.

    So those prices typically lead you to conservation. Almost always, any money/time you spend in reducing your power needs (energy efficient devices like better refrigerators, laptop vs desk top computer, CFL lights vs filament lamps, fans instead of Air Conditioning, etc.) will cost less than making a larger UPS/solar system would.

    And lastly, what type of "fail over" power glitch can you "withstand"... For example, a typical UPS failover (AC power fails, the UPS turns on in 1/2 cycle later)--will, in my experience cause the typical desktop computer to "reboot" every ~1 out of 10 power failures. But the typical TV, radio, lighting, laptop PC with internal battery will never notice the power switch over.

    Anyway--there are quite a few inverters (TSW) that include internal AC battery chargers and failover switches internally--or you can build your own system with an external battery charger and relay (for a simple backup system)...

    Anyway, I will stop here before I hit the 5,000 character limit on this forum. ;)

    Your thoughts?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • BB.BB. Super Moderators, Administrators Posts: 30,483 admin
    Re: New Member from India!

    I should add that most of us here (including the other Moderator Niel) are volunteers and not connected with NAWS or any other solar RE businesses.

    There are a few people here that are "in the business" such as WindSun (from NAWS--our host business and forum Admin in Arizona, US). And some others here that work at (typically) US equipment mfg/suppliers--perhaps they can help.

    But, as a starting point--You can look at the Outback line of TSW Inverter / Chargers so you can understand the setup.

    And you can get an idea of their US pricing here (our forum host). Unless you happen to be visiting Arizona--shipping/handling/insurance may make finding a local Outback supplier a better deal for your (including warranty support).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: New Member from India!

    ksbalaji,
    it seems to me that your priority needs might be a home backups. this would be a system with a battery bank, inverter, and utility charger. some inverters here do have the utility charger built into it and works automatically ro charge the batteries from the utility power and when that utility power goes off the inverter automatically takes over sending its power to those particular selected loads. the nice part of this type of system is that you may add solar to it later and it need not be all at once.

    solar is not cheap anywhere and in the meantime you can back up your power as i had mentioned. when you can afford some solar then you can add this to help charge the battery bank. your loads and how long you will need to power things will determine how large of a system is truly needed.

    as to who may carry items in your country and which are good we cannot say as we do not know. you can research the website i'm giving the link for so that if you don't see anything you like in your country that there may be another country you do see items you will like.
    http://www.solarbuzz.com/
    you may also read in this forum many aspects of solar power so that when you are ready to buy that you will know just what you are looking for to fulfill your needs.
  • ksbalajiksbalaji Registered Users Posts: 7
    Re: New Member from India!

    Thanks BB/Bill and Neil!

    Those three replies are stunning fast, crisp but elaborate enough and very informative feedbacks I ever received from anybody all through my life (50 years).

    I shall go by your suggestions.

    First, I have decided to go for a moderate UPS device with about 1kva output with TSW inverter, necessary batteries to take care of our utility failure for 6hours of 600watts average power consumption with a peak power consumption of about 1000 watts. ( enough to power two fans and some CFLs/TV during night power-outs I suppose?) I feel that such TSWs are quite cheap here costing about US$ 150 (could be of not so robust quality). I agree that charging the batteries through AC charger is really cheaper than using Solar panels at present. Since the failover switch is not so critical in my case, I would also try to find a suitable TSW inverter with built in AC charger.

    My fascination for Solar Power still exists notwithstanding what you have truly pointed out regarding price equations. Sooner conventional electricity might cost more and Solar cells would cost less to let me go for Solar Panels.

    I am curious to know a thing - As of now, do people having access to utility power install solar panels only for fun?

    I thank you again for your more than prompt response and expect some guidance on Solar cells from you!
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: New Member from India!

    i see you are somewhat familiar with what we refer to and that's a great plus for you. as to why people do it, now that is as variable as it can get.
    here's a few reasons i have heard of why some do this;
    1 unreliable power from a utility (like yourself)
    2 the home is too remote to the utility lines and would cost too much to hookup
    3 to get away from fossil fuels and help global warming
    4 hobby or fascinated by it (like yourself)
    5 emergency power availability
    i may have forgotten a few or even combined a few, but i think this would be the majority of reasons that i have listed. i believe i have also heard a few say they are 'sticking it to the man' and don't ask for the explanation.:confused::D
  • BB.BB. Super Moderators, Administrators Posts: 30,483 admin
    Re: New Member from India!

    ksbalaji,

    You are very welcome :D.

    Regarding $150 (USD?) TSW inverters--Even though I know nothing about inverters in India--I would pretty much be sure those are MSW inverters... The wave form is a Modified Square Wave--but most manufacturers call it a MSW or Modified Sine Wave to sound good...

    It is not.

    TSW inverters cost much more because there is much more in the way of internal electronics and (usually) copper than what makes up a MSW inverter. But--if the MSW works well for you--then why not use it.

    Lastly, why do we use solar here?

    For off grid power (more than a 1km from local power lines)---Off-Grid solar power (with generator backup) can almost be cost competitive--before government rebates and tax credits (which currently range from ~30% to 50%+).

    For me--I did it, originally, because I do not trust California's regulatory climate. We have a tiered rate structure here... The more power you use, the higher the $$ rate is.

    Imagine you walk into a corner store and buy a pint of milk for $0.50 but you go down to the local "Mega Mart" (Costco, Walmart, etc. in the USA) and buy 2 gallons of milk at a rate of $2.00 per pint)... Buy larger volumes, pay more.

    In California--our basic power rate is $0.12 per kWhr but if you have A/C or other heavy power loads--it can get up to near $0.40 per kWhr.

    In my case, using Time of Use metering, my off peak can be down to $0.09 per kWhr and my worst case summer time peak (noon-6pm Monday thru Friday) will be $0.58 per kWhr (>900 kWhrs per month usage).

    With Grid Tied solar, my power costs are currently $0.14 per kWhr (assume 25 year life, after tax rebates and credits)... So if I purchased an electric car--my Grid Tied solar system (no batteries--so no emergency backup power) is much cheaper than my utility power...

    To a degree, the pricing mess is the result of government playing around in the free market... If everyone when with GT solar--the power companies would go broke--as it is--If I recall correctly, only a maximum of 1% (or 5%) of their customers will be allowed to go Net Metered / Grid Tied... What happens if this occurs? Who knows--but I am sure there will be more laws and regulations to "fix" the problem.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • n3qikn3qik Solar Expert Posts: 741 ✭✭
    Re: New Member from India!
    niel wrote: »
    4 hobby or fascinated by it (like yourself)
    5 emergency power availability

    I did it for 4 and 5.

    Going the UPS way is best for now. Like you said electric will go up. If you use a UPS with a battery voltage of 24 or 48 DC, it will make adding solar later very simple.
  • ksbalajiksbalaji Registered Users Posts: 7
    Re: New Member from India!
    BB. wrote: »
    ksbalaji,

    You are very welcome :D.

    Regarding $150 (USD?) TSW inverters--Even though I know nothing about inverters in India--I would pretty much be sure those are MSW inverters... The wave form is a Modified Square Wave--but most manufacturers call it a MSW or Modified Sine Wave to sound good...

    It is not.
    =====edited========
    TSW inverters cost much more because there is much more in the way of internal electronics and (usually) copper than what makes up a MSW inverter. But--if the MSW works well for you--then why not use it.
    With Grid Tied solar, my power costs are currently $0.14 per kWhr (assume 25 year life, after tax rebates and credits)... So if I purchased an electric car--my Grid Tied solar system (no batteries--so no emergency backup power) is much cheaper than my utility power...

    -Bill

    Excuse me.... do you mean that your solar system gets cheaper when you purchase an electric car?
  • ksbalajiksbalaji Registered Users Posts: 7
    Re: New Member from India!
    n3qik wrote: »
    I did it for 4 and 5.

    Going the UPS way is best for now. Like you said electric will go up. If you use a UPS with a battery voltage of 24 or 48 DC, it will make adding solar later very simple.

    But some say that UPS with a battery voltage of 12 (standard) allows easy adding of solar later. The argument is that the solar cells supply a very low voltage current. Do you have a better explanation please?
  • BB.BB. Super Moderators, Administrators Posts: 30,483 admin
    Re: New Member from India!

    Basically, my "minimum" rate tier is good to about 300 kwhrs per month--higher than that, my rates double and triple.

    I use around 180-250 kWhrs per month for my home (temperate weather, no air conditioning, natural gas for heating and hot water). Plus--we are "cheap" (don't leave stuff on, did a remodel to save energy with new appliances, heater, skylights--light and ventilation, insulation, us a laptop PC for most basic computing, leave laser printer off except when printing, CFL lights even though we hate their color, etc.)...

    If I got an electric car--a doubling in our use of power would triple our energy bill...

    Now with my solar GT system and net metering--I should be able to stay in the first tier (cheap rates). Also, because I have time of use + Net Metering (power changes price between afternoon and other times, and we just turn the meter backwards--so buying and selling power is the same cost)--I can avoid afternoon loads and get paid $0.27 per kWhr and use house power + charge an electric vehicle at night at $0.09 per kWhr (not exactly--but it should work out to that plan pretty closely).

    The voltage of the battery bank is much more flexible today--Any decient (large > ~400 watt/30 amps) MPPT Solar Charge Controller can charge any battery bank between 12 and 48 VDC just fine--program the controller and away it goes.

    The advantage with 48 Volt systems is P=I*V... If you make the voltage 4x higher, the current is 1/4 as much... Lighter wire guage (less copper, less costs), smaller fuse/circuit breakers, and the ability to send 48 VDC farther with less issues of voltage drop (12 volt system at 10 volts is dead... 48 volt system at 46 volts is just fine).

    And--because large MPPT Solar Charge Controllers are rated for maximum output current (typically 60-80 amps)--the solar charge controller can handle 4x as many solar panels at 48 volts vs 12 volts. Example for charging a battery bank:

    15 volts * 60 amps = 900 watts of solar panels @ 12 battery bank.

    Run the same charge controller to a 48 VDC battery bank:

    60 volts * 60 amps = 3,600 watts of solar panels @ 48 VDC battery bank.

    Also--with the larger inverters, they can be no more expensive at 48 volts vs lower voltages (not to say they are cheap).

    Certainly, a MSW 2000 watt inverter on a 12 volt battery bank is going to be a whole bunch cheaper than a 2,600 watt 48 vdc input TSW inverter... Nothing can be done about that problem. :cry:

    -Bill

    PS: For Grid Tied solar systems--the run from ~200 to 600 VDC. My own system runs around 300-320 VDC... So just placing solar panels in series easily gets to higher voltages (Vmp for larger panels used on grid tied systems is around 24-32 volts per panel or so--put 10 in series and you got 320 volts--mine has to 10x 175 watt panel strings for a total of 20 panels @ 3,500 watts)...
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • ksbalajiksbalaji Registered Users Posts: 7
    Re: New Member from India!

    That is interesting! Is there a trade off? Something like charging from solar at higher volts and using the inverter at only 12 volts? Do I mean anything?

    I thank you for the superb links you have provided. I also note to check the forum regularly for information and also update information regarding developments in this part of the world.
  • BB.BB. Super Moderators, Administrators Posts: 30,483 admin
    Re: New Member from India!

    There are several major classes of Solar Charge controllers...

    The, typically smaller and older controllers (<400 watt / <15 amp) are PWM type units (Pulse Width Modulation)... Basically, imagine a switch that turns on and off many times a second... If the switch is on most of the time -- maximum charging current into batteries. If the switch is off most of the time, little average current into the batteries. (Duty Cycle control).

    The newer/larger charge controllers (>15 amp, >400 watt), tend to be MPPT (Maximum Power Point Tracking) type controllers...

    Really, what is called a Buck Mode Switching Power Supply... Through the use of Inductors, diodes, FETs (transistors) and computer control--the controller has the ability to behave very much like a DC version of a variable transformer.

    Basically, an MPPT type controller can very efficiently converter high voltage / low current (of the solar panels) into low voltage / high current for a battery bank (somewhere between 90%-95% efficiency at full power).

    Modern electronics and design allow efficient "matching" of Solar Panel optimum voltage / current points (Vmp/Imp/Pmp -- maximum power point) to the optimum voltage/current required by the battery...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • ksbalajiksbalaji Registered Users Posts: 7
    Re: New Member from India!

    Bill!

    Thank you again for the information.

    Also you predicted right! Please let me elaborate....

    I thought I had hit a good bargain yesterday when a retailer nearby offered to sell a 2000HPH 1200Watts inverter with 24V battery charger for Indian Rupees.6500/- (approximately USD.130/-). On persistently being asked by me, he agreed to supply a TSW inverter from a well known national company - Numeric Power Systems Limited. I straight way ordered for it and got it delivered a few hours back.

    I eagerly and cautiously went through the user manual and found the following specifications:

    Compact Rack Tower Design,
    The system is a Micro Processor Based Design,
    It boasts of:-
    Automatic line-to-battery switchover and Auto restart on AC recovery with
    transfer time 15ms typical and 50ms maximum.
    Intelligent 2-stage charger and enhanced charger
    for efficient charging and preventing overcharging,
    High efficiency conversion = Dc-to-AC >80%, AC-to-AC >95%
    Overload, Overcharge, Discharge protection
    Selectable voltage range input - narrow 170-280V for fast switchover and wide 90-280V range.
    Charge current 10 Amp +/- 1Amp
    Other indicator and Audible alarm features with a 2 year warranty.

    But importantly also find a specification that the Output waveform is Modified Sine Wave ( to make it sound good as you alerted!) and not TSW as agreed by the retailer. I guess that the retailer does not understand the difference between TSW and MSW. He would not cheat me so bluntly. Also, the price range is within that of MSWs and not that of TSWs as rightly pointed out by you.

    I am now unable to decide whether to return the inverter complaining TSW problem or to happily retain what I have got.

    To help me decide, can you give some information on devices which cannot be used with MSW input? - CFLs? Tubelights? Fans? Desktup Computer (further isolated by another UPS)? Rotary compressor-fridge?
    Cellphone charger adapters? Mixer? Hotplate?

    Please give your valuable opinion.
  • BB.BB. Super Moderators, Administrators Posts: 30,483 admin
    Re: New Member from India!

    I don't have a lot of free time at the moment--roughly 90% of the devices will work fine and 10% will die an early death--the problem is figuring out which ones (and many will not give any warning)...

    For now, please read these two FAQ's from our host's webstore:

    All About Inverters
    Choosing an inverter for water pumping

    It should help you in your decision/formulate further questions.

    The short answer is it depends on your needs, vunerability to failures/problems, and your available funds.

    Many times, people can purchase a large/cheap MSW inverter and run the "big stuff" that works well on MSW. And purchase a smaller (less costly) TSW for the wall plugs, refrigerators, etc. that don't.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • ksbalajiksbalaji Registered Users Posts: 7
    Re: New Member from India!
    BB. wrote: »
    I don't have a lot of free time at the moment--roughly 90% of the devices will work fine and 10% will die an early death--the problem is figuring out which ones (and many will not give any warning)...
    For now, please read these two FAQ's from our host's webstore:
    All About Inverters
    Choosing an inverter for water pumping
    It should help you in your decision/formulate further questions.
    The short answer is it depends on your needs, vunerability to failures/problems, and your available funds.

    The links are very informative.
    I am unable to resist appreciating your fast response once again, though you claim unavailability of time.
    The following last part of your post got things cleared. I have decided to retain the MSW inverter. Still, I have to appraise the retailer who wrongly delivered it, regarding TSW inverters.
    BB. wrote: »

    Many times, people can purchase a large/cheap MSW inverter and run the "big stuff" that works well on MSW. And purchase a smaller (less costly) TSW for the wall plugs, refrigerators, etc. that don't.
    -Bill
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