planning a hybrid off grid system can use some help which parts

sunspot
sunspot Registered Users Posts: 6 ✭
in Solar Beginners Corner #1
I am grateful for this site. And all the people sharing and helping with renewable energy projects. I wish to ask for help and I wrote my questions here:

1. please help me verify accuracy of my calculations and to choose parts such as inverter, charge controller, batteries. Like do I need a 500 watt inverter or how do I choose?

2. By the way... how do you wire up the panels? Do you do this at night so they don't get juice, or do you cover them with black fabric? Do you know why I am asking - to avoid shock. I feel I solved this issue for the turbine. It will be raised already installed on the pole. it is not a grid tie system so just the live current from the panels is my concern. Also do I wire the batteries first or the panels?

my loads daily
fridge 1.4 kw per day. i used kilowatt meter to find out.
washer used once weekly-i can unplug the fridge during washing, yes?
led lights, negligible
vacuum 0.2 once weekly
computer 0.5

so really i just need the fridge and computer to running same time. the washer can run alone by me unplugging the fridge for 25 minutes

that means my total need is 1.4 fridge + 0.5 computer = 1.9 kw daily i require.

3. planning parts to produce 1.9 kw
(400 watt solar x 5 hours sun x .85 efficiency) / 1000 = 1.7 kw probable production
400 watt wind gen x ? wind = minimum .2 kw day but most likely 2 kw.

4. Can I wire the wind gen and solar array to same inverter, yes? or do they need to be separate?

5. is it true what i heard that a 400 watt wind turbine produces 400 watts in ideal wind per hour/ so if the wind is 12 mph for 1 hour then i am getting 400 watts that hour/ that is incredible? does wind or solar goive more juice per hour for cost comparison? which is more relibale? i figure a hybrid system is good to hedge bets and get sun and wind power. do turbines break often? would be shame if it did at $700 it is expensive

6. the solar system should cost < can anyone confirm my estimated costs please:
400 watts x $2.50 = $1000
inverter = ?? $120??
charge controller = $60
do it yourself solar racks and wires= $310
turbine 400 watt $700
pole and guyed wires $100
batteries how many and what type and brand?? = 2 x $50 = $100
gas generator - how many watts? = $300
total 2690
7. what watts gas generator should i get? and what about these quiet ones i read in magazine article, can i say the magazine reference? for example, to run fridge and computer 1.4 + 0.5 = 1.9 kw day, how much gas will my generator use/ cost me per day? like if the sun is not out and if the wind is not blowing, do i run the fridge every couple hours for 20 minutes?

8. what exactly does a small 20 gallon water heater use to start up? what about the really small ones like 7 gallons? what about tankless, how much power is needed and do people use them on solar systems or are they power hogs? also the water pressure has to be high so i dont know if this is fixable with an adaptor.i wish tio find out what is the water heater i can get that uses the elast amount fo electricty, anyone know about it? i imgaine this si the biggest item for off grid homeowners. what do people do? which water heater uses the least? there is a 2 gallon water heater - hahaha. I know, but having a QUICK hot shower is better than, NOT. hehe

9. which batteries and how many and which type? I want to be powered during snow storms and cloudy days, so should i plan for 2 days of battery power and have a gas generator as back up? If batteries are expensive then cant I just use batteries for overnight use for fridge and computer but then i can use gas generator in case of cloudy days or non windy days - is this feasible? if not why not? the reason i sued 5 hours sun is to account for winter sun. most likely the sun will be 7 hours but i am trying to be accurate and error on the safe side.

10. please help me choose inverter like how many watts or amps i dont know how to choose it. if fridge is my largest load then the start up load of the fridge should be my factor in choosing the inverter right? so maybe 3 kw for the fridge to start its motor? can i use any brand as long as it supplies the correct watt service?
11. also, in case i am able to afford to increase my system in couple years, i want to use panels and batteries that i can just add on to? my system leaves out the water heater since i feel they are hogs and i cant support it right now. some people heat water on wood stove for bathing and that is ok. i will build a summer spring solar passive water hose system but that is not good for winter. i may try a do it yourtself winter water soloar heater but maybe next year. i will have to find DIY instructions on how to do it.

12. It always struck me as funny that for those that don't mind conserving, then why not just unplug the fridge when you want to run other items since they are just running for short times like washer machine. This is satisfy the system plan for a homeowner that can only built an inexpensive system for bare minimum powering. dont get me wrong, i want reliable energy so i want to be sure my system will produce "enough' but i dont have lots of money,... due to thieves and other family and lawyers and low level beings that steal and are criminals..

if anyone has 'good' family, the treasure them. mine are criminals, thieves and terror war mongers.. pray for peace. peace is upon us.
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  • audredger
    audredger Solar Expert Posts: 272 ✭✭
    #2
    Re: planning a hybrid off grid system can use some help which parts

    OK, lest start one thing at a time.... Inverter size should be 1 1/2 X the maximum load.
    To size the inverter at you max load leaves no room for expansion and works the inverter too hard! The inverter should be a full sine wave type, modified sine wave is too hard on motors and electronics.

    You say your loads are 1.9Kwh but your panels are only going to give 1.4Kwh? How are you going to make up the difference?
    do turbines break often? would be shame if it did at $700 it is expensive
    Answer is YES! Small scale wind is generaly unreliable, there are exceptions but few.
    pole and guyed wires $100
    Too little money!
    batteries how many and what type and brand?? = 2 x $50 = $100
    Way to little money!!! $50 batteries won't cut it!! more like $350 batteries X ?
    gas generator - how many watts? = $300
    A Honda eu3000i is just short of $1,000


    If money is tight then you need to know OFF GRID POWER IS EXPENSIVE! Not just to purchace but to run.... a reasonable figure is $1.00 / Kwh.
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  • sunspot
    sunspot Registered Users Posts: 6 ✭
    #3
    Re: planning a hybrid off grid system can use some help which parts

    hi! thanks for writing me. i am a humble solar sunspot wanna be.

    ok so max load is fridge at 1.4 kw per day with 2.4 kw start up load. should i 1.5 x the regular load or the start up load?

    so if it is 1.5 x 2.4 = 3.6 kw what will the inverter say on the box, how to relate the inverter to 3.6? what words are used?

    ok i will get a sine wave inverter.
    audredger wrote: »
    OK, lest start one thing at a time.... Inverter size should be 1 1/2 X the maximum load.
    To size the inverter at you max load leaves no room for expansion and works the inverter too hard! The inverter should be a full sine wave type, modified sine wave is too hard on motors and electronics.

    You say your loads are 1.9Kwh but your panels are only going to give 1.4Kwh? How are you going to make up the difference?

    wind turbine 400 watts costs $700. pole is metal plumbing pipes and 4 guyed wires are wire of strong guage, or strong rope, i dont know yet. ok so i should allow for more than $100 for this, thanks.

    Answer is YES! Small scale wind is generaly unreliable, there are exceptions but few.
    Too little money!
    Way to little money!!! $50 batteries won't cut it!! more like $350 batteries X ?

    well i didnt know much about batteries. some solar arrays are using $50 batteries from sams club, golf cart type. when you say $350 is that battery larger or has more capacity? may i ask details i am ready to purchase and am trying to nail down items and design my system

    A Honda eu3000i is just short of $1,000
    well that is a super quiet one i am reading about it now. like is it really quiet or just not like a jackhammer in your face? like can hear yourself humming softly near it?

    If money is tight then you need to know OFF GRID POWER IS EXPENSIVE! Not just to purchace but to run.... a reasonable figure is $1.00 / Kwh.

    what does $1.00 per kwh mean, i am sorry i cannot seem to understand this.
    here is video about a 600 watt solar array and 400 watt wind turbine. it costs $3900 and produces 3 kw per day. well if am wrong pls correct me. i hope you can watch the video and tell me if it seems ontrack or if not which detail is wrong?

    i wish i can just get the specs on a system i an afford and install. long sigh it is like a year trek into mysetryville but i have learned alot due to people sharing like you.

    what does it cost to run your generator, was it you that wrote you use it for 80 hours per year? how many hours per day do you use it when there is no sun or to very little winter sun? is winter a tough time for lack of sun or do you get 5 hours full sun to charge your system? so you have 320 amp hours, how many baterries is this? how do apply 320 amp hours to relate this to a 700 watt system?

    700 watts = 320 than what / 50%? or mult by 50 for half battery use?

    are batteries only meant to be discharged half way over night or for back up?

    i want to know how much is used over night from fridge and computer? computer wil use 0.5 kw so how to relate this to battery use?


    http://www.youtube.com/watch?v=6P2RuuA-GqM
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  • audredger
    audredger Solar Expert Posts: 272 ✭✭
    #4
    Re: planning a hybrid off grid system can use some help which parts
    ok so max load is fridge at 1.4 kw per day with 2.4 kw start up load. should i 1.5 x the regular load or the start up load?
    so if it is 1.5 x 2.4 = 3.6 kw what will the inverter say on the box, how to relate the inverter to 3.6? what words are used

    Somethig is not right with your numbers .... "frige at 1.4 kw per day" .... 1400 watts = 12.7 amps @ 110 but for how long? Do you mean 1.4 Kwh? (Killowatt Hours)

    2.4 Kw start up is 21.8 amps @ 110 volt ... That ought to trip most 15amp breakers.

    Yes 1.5 x "2.4" or 1.5 x "max total load" Total load: frige + computer + lights + ? + ?
    3.6? what words are used?
    3.6 = 3600watt
    wind turbine 400 watts costs $700. pole is metal plumbing pipes and 4 guyed wires are wire of strong guage, or strong rope, i dont know yet. ok so i should allow for more than $100 for this, thanks.

    Plumbing pipes = too weak ... rope = too much give A turbine on top of a 30 or 50' mast in a 12mph wind exerts one Heck of a lot of force!
    well i didnt know much about batteries. some solar arrays are using $50 batteries from sams club, golf cart type. when you say $350 is that battery larger or has more capacity? may i ask details i am ready to purchase and am trying to nail down items and design my system

    Marine type batteries do not last.. I'm talking about a 420ah 6volt deep cycle battery
    what does $1.00 per kwh mean, i am sorry i cannot seem to understand this.

    Elictricity is sold by the Kwh (Killowatt Hour) My friends pay ~ 14 cent a killowatt hour .. off grid costs about 1 dollar a killowatt hour
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,623 admin
    #5
    Re: planning a hybrid off grid system can use some help which parts

    ok so max load is fridge at 1.4 kw per day with 2.4 kw start up load. should i 1.5 x the regular load or the start up load?
    First, we need to clarify the difference between Watts and Watt*Hours...

    Watts is a rate (like miles per hour or gallons per hour) and Watts*Time (Hours in our case) is an amount (like miles driven or total gallons pumped)...

    And the "k" means Kilo--Or 1,000. So 1,000 Watts = 1 kWatt.

    A good quality Energy Star Rated ~15 cuft refrigerator (no ice maker) may use around 120 watts running, may use over 600 watts (5x) starting, and may use another 500 watts to run the defrost/deicing heaters (frost free model).

    That all works out to needing, roughly a 1,500 watt inverter just to "power the fridge" and perhaps a few CFL (compact florescent lamps).

    But, that is only part of the equation--How many hours do these things run... The motor may run 6-8 hours a day (even more in hot weather). The defrost heaters probably only a few minutes per day)... All told, that may add up to 1,000 WH per day (or 1kWH per day).
    so if it is 1.5 x 2.4 = 3.6 kw what will the inverter say on the box, how to relate the inverter to 3.6? what words are used?
    So, what we are looking for in an inverter is one that can sustain the peak loads (Watts) that you expect for your system. Realizing that motors (for example) can take 5x their nameplate power/amp rating while starting and that inverters (unlike generators) do not have much surge capacity over their "nameplate" rating.

    It is a tough road to follow--Guessing at how much surge current you will need vs getting too large of inverter for your needs (large inverters can waste a lot of power).

    Telling somebody else about your needs / equipment and see who has a similar setup can confirm if yours would work.
    ok i will get a sine wave inverter.
    True or Pure Sine wave inverters are much closer to utility power in the quality of their output.

    MSW inverters can run ~80% of the equipment (AC electric drills, many lights and appliances). And on ~10% of the appliances, an MSW inverter can cause the appliances to over heat and shorten their lives and sometimes kill them in minutes or a few hours.

    Small wall mount transforms/power supplies, many refrigerators, some computers/electronics, and items with heavily loaded motors (deep well pumps)... The problem is you do not know up front, may times, which items will work OK and which will fail.

    And TSW inverters are way more expensive vs MSW inverters.
    audredger wrote: »
    OK, lest start one thing at a time.... Inverter size should be 1 1/2 X the maximum load.
    To size the inverter at you max load leaves no room for expansion and works the inverter too hard! The inverter should be a full sine wave type, modified sine wave is too hard on motors and electronics.

    You say your loads are 1.9Kwh but your panels are only going to give 1.4Kwh? How are you going to make up the difference?

    wind turbine 400 watts costs $700. pole is metal plumbing pipes and 4 guyed wires are wire of strong guage, or strong rope, i dont know yet. ok so i should allow for more than $100 for this, thanks.

    For a starting system--I would plan on solar PV panels only to power my home... Later, after you have a stable setup running--You can play with wind turbines.

    But be warned, the wind turbines are the "cheap part" of the system. To get reasonable amount of power, you need to be, at least, 30 feet, and in reality 60' above the ground. And 30' feet above roofs/trees and 500' away from other major obstructions with respect to prevailing winds.

    And, the trees in your area should be "flagging" from prevailing winds to even have much hope that there is enough wind power in your area (a few areas like Florida may not have strong prevailing winds). Also, if you are are in a lightning prone region (like Florida)--Protecting against strikes is very difficult.
    Answer is YES! Small scale wind is generaly unreliable, there are exceptions but few.
    Too little money!
    Way to little money!!! $50 batteries won't cut it!! more like $350 batteries X ?

    well i didnt know much about batteries. some solar arrays are using $50 batteries from sams club, golf cart type. when you say $350 is that battery larger or has more capacity? may i ask details i am ready to purchase and am trying to nail down items and design my system
    First, we need to define how many batteries you will want to use... Normally, a good starting point is to plan for 3 days of no power and 50% maximum discharge (for longer battery life).

    A good starting point for an off-grid home is around 3.3 kWH per day (100 kWH per month)... For a 24 volt battery bank:
    • 3,300 WH * 1/24 volts * 1/0.85 inverter efficiency * 3 days * 1/0.50 max discharge = 970 Amp*Hour @ 24 volt battery bank
    That is not a small battery bank (about 20x the size of a normal automotive battery).

    About 12 of these guys would work very nicely:
    wind-sun_2125_47700482Trojan L16RE-2V 1110 AH 2-Volt Deep Cycle Battery
    Price: $330.00


    End part 1
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,623 admin
    #6
    Re: planning a hybrid off grid system can use some help which parts

    Part II

    A Honda eu3000i is just short of $1,000
    well that is a super quiet one i am reading about it now. like is it really quiet or just not like a jackhammer in your face? like can hear yourself humming softly near it?
    The eu1000i, 2000, and 3000 gensets are very quiet. You can easily hold a conversation standing right next to one... And if you are on a city street or busy park--you might not even hear it running as you walk by.
    If money is tight then you need to know OFF GRID POWER IS EXPENSIVE! Not just to purchace but to run.... a reasonable figure is $1.00 / Kwh.
    what does $1.00 per kwh mean, i am sorry i cannot seem to understand this.
    here is video about a 600 watt solar array and 400 watt wind turbine. it costs $3900 and produces 3 kw per day. well if am wrong pls correct me. i hope you can watch the video and tell me if it seems ontrack or if not which detail is wrong?


    I watched your video--And it is OK as a start... However, there are a lot more factors that you are not taking into account... A realist derating for a Off-Grid solar powered system is around 0.52--Yes, 1/2 the power you expected to get... The charge controller, battery, and inverters all have losses themselves too.

    Also, the estimate of power used in a home is quite low... I use about 7-8 kWH per day for my on-grid powered home and I probably use 1/2 or less of anyone nearby.

    A home that uses 3.3 kWH per day is severely restricting power use for most people. A refrigerator, a few lights, a laptop computer, small well pump, and perhaps an electric washing machine will use up much of that power.

    Also, sunlight is very location and weather dependent... For example Houston Texas, hours of "full sun" per day:
    1, 3.68
    2, 4.12
    3, 4.82
    4, 4.98
    5, 5.24
    6, 5.53
    7, 5.43
    8, 5.44
    9, 5.40
    10, 5.19
    11, 4.33
    12, 3.34
    If you want to live on 3.3 kWH per day for 9 months of the year, then you need to plan on ~4.82 hours of sun minimum.
    • 3,300 WH per day * 1/0.52 system eff * 1/4.82 hours of sun per day = 1,317 watts of solar panels minimum
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,623 admin
    #7
    Re: planning a hybrid off grid system can use some help which parts

    Part III
    i wish i can just get the specs on a system i an afford and install. long sigh it is like a year trek into mysetryville but i have learned alot due to people sharing like you.
    Ok--So there are a few specifications for you to start with:
    • 3.3 kWH or 3,300 WH per day system, 9 months of the year, Houston TX
    • 970 AH @ 24 volt battery bank
    • 1,500-2,400 watt 24 volt TSW inverter
    • 1,317 to 2,600 watts of solar panels (more panels for more daily loads)
    • 1-2 60 amp MPPT type solar charge controllers (depending on panels)
    • 45-90+ amp 24 volt AC charge controller (plug into generator)
    • ~3,000 to 6,000+ watt generator (for cloudy weather--depending on battery charger size/model chosen)
    And that will give you a fairly nice existence for an off-grid home with possibly some left over power for a washer, TV, DVD player (more panels will support more optional loads).

    The above system is "balanced" between power needs, battery bank size, solar array size, and generator size...

    Nothing is written in stone and things can be moved around some--But the farther you go from "optimum" the more issues an arise.
    what does it cost to run your generator, was it you that wrote you use it for 80 hours per year? how many hours per day do you use it when there is no sun or to very little winter sun? is winter a tough time for lack of sun or do you get 5 hours full sun to charge your system? so you have 320 amp hours, how many batteries is this? how do apply 320 amp hours to relate this to a 700 watt system?
    You can guess that one gallon of gasoline will generate around 1-5kWH of electricity. $3.00 per gallons and 3kWH generated (reasonably efficient generator operations) and you are looking at $1.00 per kWH of electricity used.
    are batteries only meant to be discharged half way over night or for back up?
    The deeper you cycle a lead acid battery bank, the shorter life they will have... However, if you double the number of batteries, the battery bank will probably only last 2.2x longer--So the actual cost of battery energy storage is about the same.

    Ideally, you want to use about 25% or less of a battery bank's capacity overnight. The 3 day / 50% rule I gave you makes for a rather large battery bank and 1/6th (~17% bank energy per night).

    You don't want to keep your battery long below 75% state of charge for days/weeks/months at a time--This causes sulfates to harden and reduces the battery bank capacity (eventually to zero AH storage capacity).
    i want to know how much is used over night from fridge and computer? computer will use 0.5 kw so how to relate this to battery use?
    Your Fridge + laptop computer will probably use closer to 1 kWH over night:
    • 1,000 watts * 1/0.85 inverter eff * 1/24 volt battery bank = 49 AH used (at 24 volts)
    For a 100 AH 24 volt battery bank , this would be about 1/2 the battery bank's capacity.

    Roughly, you can see that a generator, just in fuel costs, will easily run $1.00 per kWH. For an off-grid solar PV system, you are looking at $1-$2 per kWH (battery replacement every 3-8 years will greatly affect your costs).

    And utility power costs most people around $0.10 to $0.20 per kWH...

    Off Grid power will cost you about 10x that what Grid Power or Grid Tied solar power will cost you.

    A few links to review:

    Deep Cycle Battery FAQ
    www.batteryfaq.org

    Wind Power Links
    www.otherpower.com (good forum for DIY Wind Power)
    Small windpower a scam ? Survey says SO
    Truth About Skystream & SWWP

    And a general DIY Solar Builder site (the one you mentioned?):

    www.builditsolar.com

    Working Thread for Solar Beginner Post/FAQ

    In the end, if you are planning on going off grid--plan on replacing the wind turbine every few years, the batteries every 3-8+ years, the Inverter/Charge controllers every 10-15 years, and the solar panels every 10-25+ years... All of this depending on the quality of the products, how they are treated, and your luck with rocks, hail, wind, lightning, and electronics.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,623 admin
    #8
    Re: planning a hybrid off grid system can use some help which parts

    By the way, here is a picture o, probably, the same wind turbine model as in your Youtube presentation after a few hours of operation:

    Inside a Chinese wind turbine nacelle

    In general, wind turbines require a lot of maintenance, a high tower, attract lightning, and only produce significant power in areas/times when the wind is irritating to people.

    If you have the time, money, and energy to experiment with a cabin/home sized turbine to assist you in your power generation as a secondary source--Not a problem. But they are, in general, no less expensive than a good solar panel system for most folks these days.

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