need configuration info..

wie69

hello.
i am jon from indonesia, medan city. i am new to this forum and want to ask some question about solar power.

my roof installed 16pcs pv with specs
rated max power : 150Wp
rated voltage : 35.8V
rated current : 4.2A
Open circuit voltage : 42.9V
Short circuit current : 4.56A

outback solar charge controller FM80 with 150vdc pv input

48 volt 400Amp battery bank

at this point what is the best suggestion for any series or parallel combination to connect FM80 to charge 48volt battery bank ?

fyi: i have combiner box with 8 fuses installed for each strings, each fuse is 10A , is this fuse enought ?

last sorry for my bad english, coz i am still learn.

regards

JON

solarix

Re: need configuration info..

The 150V input limit on the controller restricts you to 3 or less panels in series. Because you have an even number of 16 panels, you will have to go with 8 series strings of just 2 panels which will take fairly large wire from the combiner to the FM80. On the other hand this has benefit of running the FM80 at a lower voltage (about 70V) where it will be most efficient.

BB.

Re: need configuration info..

Welcome to the forum. Your English is better than my any another language (and you may be better than my English with a bit more practice ).

With typical solar charge controllers, generally there is a minimum array voltage. For:

12 volt battery bank is it roughly 17.5 volts minimum Vmp-array
24 volt battery bank is ~35 volts
48 volt battery bank is ~70 volts

This is because Vmp fall as the panels get hot in full sun/hot weather. And batteries need ~15 volts to fully/quickly charge (battery charging voltage requirements fall a bit as the batteries themselves get hot).

The maximum array voltage is based on the Voc-cold rating (Voltage open circuit--As array gets cold, winter, early morning, etc.), the Voc-cold rises... For a typical MPPT controller with a Vmax input of ~140 to 150 VAC, the maximum Vmp-array (rated voltage at STC--standard test conditions) is around Vmp-array=~100 VDC. If you run higher than that, in cold climates, the Voc-cold could exceed the ~140-150 VDC input limit. If you live in a warm climate, you can run Vmp-array a bit higher.

And that is why many controller manufacturers make automated web page (String Sizing Tool) where you fill out the planned system details (size, temperature, controller model, etc.) and it will tell you the optimum array configuration.

http://www.outbackpower.com/outback-resources/string-sizing-tool

Typically, Vmp-array about 2x the battery bank voltage is "optimum" controller efficiency (as the Vmp-array rises, most controllers become slightly less efficient).

If you have a longer wire run from the Array to the controller/battery shed, you typically want to run towards a higher Vmp-array... This allows you do use smaller diameter (less expensive) wire from the array to the charge controller.

-Bill

wie69

Re: need configuration info..

many thanks for reply..

so 2 series pv and 8 parallel is safety, but only get minimum pv voltage.
if i change the battery bank from 48v to 24v. its waste energy ? or to much pv voltage or else ?

jon

BB.

Re: need configuration info..

You probably want to stay with a 48 volt battery bank if you keep the same storage (400 AH @ 48 volts). At 10% rate of charge, that is ~40 amps from the FM 80 + array.

If you drop to 24 volts, then you are looking at an 800 AH 24 volt battery bank, 10% rate of charge is 80 amps and leaves you no headroom to grow the array later.

A 2,400 Watt solar array is a bit small for a 400 AH @ 48 volt battery bank:

• 2,400 Watt * 0.77 panel+controller derate * 1/59 volts charging = 31 Amp charging current
• 31 amps charging / 400 AH bank = 0.0775 = 7.8% rate of charge

That is an "OK" charging rate--For lightly loaded/weekend use, a 5% rate of charge can be OK. For daily use/heavy loaded system used 9+ months of the year, many times, you really should be looking at 10%+ rate of charge. Part of the question is do you have "optional loads" and how much daily power management do you want to do (more panels can make the system "easier/less work" to manage day to day).

A 13% rate of charge, 400 AH @ 48 AH battery bank:

• 400 AH * 59 volts charging * 1/0.77 rate of charge * 0.13 rate of charge = 3,984 Watt array (very nice sized array for batter bank).

You did not say anything about your loads--In the end, that is why you have your solar power system--To power the loads you need to run.

Questions like, what is the peak loads (starting a well pump, running a microwave) and long term average powers (running a microwave for 20 minutes a day is not a "big deal"--Running a water pump 8 hours a day for irrigation, or even one or two refrigerator/freezers, computer server, etc. can draw low peak power, but use lots of energy--kWatt*Hours per day).

-Bill

wie69

Re: need configuration info..

thx bill for reply.

ok now i am not ready to make a choice,
i have 2 inverter that i need to make sure which one to use, so i have some of part.

1. 48volt 6000watt sinewave + built in charger 80A
2. 24volt 3000watt sineware + built in charger 60A + built in solar charge controller 40A with 55volt max pv input. this hybrid inv
this 2 type inverter i need to make sure which one is best for me.

i have 8 pcs 12volt 200A battery that i can make 48v or 24v

peak load is no more 3000 watt, daily i use average 4500 to 5500 KWH base on my grid meter.

for your information my grid is 16amp 220volt ac it meet 3500watt, but never use more than 3000watt.

so many thank for advice the best choice for me.

jon

BB.

Re: need configuration info..

wie69 wrote: »

1. 48volt 6000watt sinewave + built in charger 80A
2. 24volt 3000watt sineware + built in charger 60A + built in solar charge controller 40A with 55volt max pv input. this hybrid inv
this 2 type inverter i need to make sure which one is best for me.

#2 -- An "all in one" inverter/AC charger/Solar Charger--Not my favorite to use an All-in-one. The solar charge controller side is usually quite limited in function/programability. Also, it limits you to a Vmp-array of ~35 volts. That means very heavy copper cables from the array to the charge controller--Very expensive if you have more than a few meters from the array to the battery shed.

If you run the FM 80 with Vmp-array >~70 volts (especially on a 48 volt battery bank)--The cabling can be much thinner/array mounted father away with the Outback MPPT type charge controller.

2,400 Watt to around 3,000 Watt would be about the maximum size AC inverter I would suggest on a 24 volt battery bank.

With a 400 AH @ 48 volt battery bank, about 4kWatt is the maximum power I would suggest drawing (continuous, 8kW surge maximum).

Larger than needed AC inverters can use more power (idle losses) than smaller AC inverters... Check the "tare" or idling losses for your 6kWatt @ 48 volt inverter and make sure that it does not "waste" too much power for your needs.

i have 8 pcs 12volt 200A battery that i can make 48v or 24v

Are these "true" deep cycle batteries (flooded cell, or other type?)--Or are these truck or UPS batteries?

peak load is no more 3000 watt, daily i use average 4500 to 5500 KWH base on my grid meter.

That is still a fair amount of power... If you assume 2 days of storage and 50% maximum discharge:

5,500 WH * 1/0.85 AC inverter eff * 1/48 volt battery bank * 2 days of storage * 1/0.50 max discharge = 539 AH @ 48 volt battery bank "recommended"/Nominal

The 400 AH battery bank is a bit less--But if you use a fair amount of power during the day, and can cut on power usage during bad weather (i.e., residence vs a business), it could work OK for you.

for your information my grid is 16amp 220volt ac it meet 3500watt, but never use more than 3000watt.

You will want to make sure you are using efficient appliances and don't run heavy loads at the same time (i.e., microwave and well pump at the same time). If you can conserve/reduce your power needs, it can help you save on your off grid system costs.

Using the Solar Electric Handbook for Medan Indonesia, array near flat (~4 degrees from horizontal):

Medan
Average Solar Insolation figures

Measured in kWh/m²/day onto a solar panel set at a 86° angle:
(For best year-round performance)

Jan
Feb
Mar
Apr
May
Jun


4.73
5.09
4.89
4.74
4.78
4.80


Jul
Aug
Sep
Oct
Nov
Dec


4.60
4.45
4.09
4.28
4.23
4.37


To generate ~5,500 WH per day with a minimum of 4 hours of sun per day:

5,500 WH * 1/0.52 system eff * 1/4 hours of sun per day = 2,644 Watt array minimum

This all making sense to you?

-Bill

wie69

Re: need configuration info..

hi Bill

my batteries is Luminous Sealed Maintenance Free Batteries LUM 12V 200Ah @20Hr
is design for inverter use.
i make sure not use the load at same time.
both inverter have saving mode, so how much do use it can adjust the power out so not waste energy from batteries

i more like use @2 24volt 3000watt inverter, i can set to hybrid mode, at night if the batteries voltage reach to 21volt,
then its switch over to grid (using grid as backup).
is true that built in solar charge controller is quite limited in function, but i dont use it.
i use outback FM80 to charge the batteries. so when the batteries reach 27volt its back to invert mode (using batteries).

back to question.
if i use 24volt battery bank, i get 800amp right (i can add more 400amp which total 1200amp if needed).
so if using 2 series 8 parallel pv to outback FM80 to charge 800amp batteries is to less or to much or waste energy at pv side?

if using 48volt 6000watt inverter, its to much because when i use at full load at night is only 48% of power use it,even using saving mode.
but the batteries i can use 400amp only (i can add more 200amp which total 600amp if needed).

i have no idea about Average Solar Insolation figures base on Solar Electric Handbook for Medan city, Indonesia Country.
at my place only have 2 season ( summer and rainy season).
at summer season, 5 or 6 hours of sun per day can be reach.
at rainy, minimum 4 hours of sun per day can be reach but not all days in 6 months

if base on you calculation,

5500 WH * 1/052 system eff * 1/5 hours of sun per day = 2115 Watt array minimum

what do you think ?

fyi:
from pv array to combiner it 8 meters long wire, that i use 6mm of each strings to combiners,
and from combiners to SCC is only 1 meter using 16mm wire
from FM80 SCC to Batteries Bus Bar is only 2 meters using 16mm, and from inverter to batteries is 1.2 meter using 35mm wire.

here we use meter for length, and use mm for cable thicker.

Jon

wie69

Re: need configuration info..

Hi Bill
i have an idea,
16 panels 150wp installed at my roof devide into 2 part.
1 part is 2 series 6 parallel is connect to Outback FM80 so total panel is 12 panels, then the rest is 4 panels i made in parallel to connect built in solar charge controller in inverter side.

so 2 source charger to charge the battery bank 24volt 800amp, what do you think Bill ? is safety using 2 source charger ?

JON

BB.

Re: need configuration info..

Hi Jon,

wie69 wrote: »

i more like use @2 24volt 3000watt inverter, i can set to hybrid mode, at night if the batteries voltage reach to 21volt,
then its switch over to grid (using grid as backup).

21 volts (resting) is a "dead" battery bank... You generally do not want to take your batteries that low (lead acid batteries do not last long if deep cycled that far). You generally do not want to go much below 50% state of charge for longer battery life.

Estimating battery capacity by measuring the bank voltage is not accurate--But if you want a starting point, setting your minimum voltage to somewhere around ~23 volts minimum would be better. (typically 23 to 24 volts minimum--depending on loads, temperature, your needs).

is true that built in solar charge controller is quite limited in function, but i dont use it.
i use outback FM80 to charge the batteries. so when the batteries reach 27volt its back to invert mode (using batteries).

That should work.

back to question.
if i use 24volt battery bank, i get 800amp right (i can add more 400amp which total 1200amp if needed).
so if using 2 series 8 parallel pv to outback FM80 to charge 800amp batteries is to less or to much or waste energy at pv side?

If you want to add more solar panels, you will need 2x FM 80 charge controllers (10% of an 800 AH battery bank is ~80 amps charging). It certainly can be done and lets you add fewer batteries at 24 volts to increase capacity (2x 12 volt batteries per 24 volt string vs 4x 12 volt batteries per 48 volt string).

1,200 AH is getting towards the maximum size battery bank I would suggest. Wire gets very large diameter to manage that much current. Expensive and difficult to work with.

if using 48volt 6000watt inverter, its to much because when i use at full load at night is only 48% of power use it,even using saving mode.
but the batteries i can use 400amp only (i can add more 200amp which total 600amp if needed).

In general, I would be suggesting the 48 volt battery bank as being easier/cheaper to wire up. There is an issue with 48 volt battery banks. It can be more difficult to get 60+ volt rated circuit breakers, fuses, switches. If you have difficulty getting 60-150 VDC rated components, that may be a very good reason to stay at 24 volts for the battery bank.

i have no idea about Average Solar Insolation figures base on Solar Electric Handbook for Medan city, Indonesia Country.
at my place only have 2 season ( summer and rainy season).
at summer season, 5 or 6 hours of sun per day can be reach.
at rainy, minimum 4 hours of sun per day can be reach but not all days in 6 months

The solar power numbers I gave you are based (usually) on a long term average (10-20 years or more). And, you are correct, in that if you have 6 days of rain, you will get next to no solar power (need grid/backup generator for power).

We use "5 hours of sun" to mean 5 hours of "noon time" equivalent sun at ~1,000 Watts per square meter. You may get 8-12 hours of sun light per day--But for a fixed array, based on average weather and sun location in the sky, you only average 4-5 hours of 1,000 W/sqmtr worth of sun per day (lots of clouds, hazy days it sounds like).

if base on you calculation,

5500 WH * 1/052 system eff * 1/5 hours of sun per day = 2115 Watt array minimum

what do you think ?

You only get ~5.09 hours of sun per day in February... On average, I would use 4 hours of sun as this will be a better minimum number and closer to "real life".

You have grid power, and if, on average, your power is reasonably stable, you could use a smaller array and simply feed from the grid/backup generator/or simply cut power use when needed.

But, remember that you also want to keep the batteries "happy" with a minimum rate of charge... In general, you want 5% to 13% rate of charge with 10% or more for charging deep cycled/daily use off grid battery bank. 5% rate of charge is the absolute minimum (you can go upwards of 20-25% rate of charge--But that is usually not needed for solar panels--Sometimes people will go with ~20=25% maximum for their backup AC battery chargers).

It really depends on how much you want to use your solar array--And how much you want to "manage" your power usage.

With batteries, it only takes one mistake (such as draining to 21 volts) to kill your battery bank (or cut years off its service life). In general, a good sized array will help you keep the battery bank well charged.

from pv array to combiner it 8 meters long wire, that i use 6mm of each strings to combiners,
and from combiners to SCC is only 1 meter using 16mm wire
from FM80 SCC to Batteries Bus Bar is only 2 meters using 16mm, and from inverter to batteries is 1.2 meter using 35mm wire.

here we use meter for length, and use mm for cable thicker.

Do you use mm (cable diameter) or mm² (cable area) for cable sizing?



American Wire Gauge
(AWG)
Diameter
(inches)
Diameter
(mm)
Cross Sectional Area
(mm²)


0000
0.46
11.68
107.16


000
0.4096
10.40
84.97


00
0.3648
9.27
67.40


0
0.3249
8.25
53.46


1
0.2893
7.35
42.39


2
0.2576
6.54
33.61


3
0.2294
5.83
26.65


4
0.2043
5.19
21.14


5
0.1819
4.62
16.76


6
0.162
4.11
13.29



16 mm cable is not very heavy (we would use it for around 80 amps for home/business wiring). 16 mm² is very heavy cable.

• 3,000 Watt inverter * 1/0.85 inverter efficiency * 1/21 volts minimum battery = 168 Amps maximum current (2x that for surge)

In the US, we would further derate that by x1.25 for sizing fuses/breakers/wiring:

• 168 amps * 1.25 National Electric Code derating = 210 Amps breaker/wiring/branch circuit rating

The absolute maximum current (much less conservative than NEC tables):

http://www.powerstream.com/Wire_Size.htm



WG gauge
Conductor
Diameter Inches
Conductor
Diameter mm
Ohms per 1000 ft.
Ohms per km
Maximum amps for chassis wiring
Maximum amps for
power transmission
Maximum frequency for
100% skin depth for solid conductor copper
Breaking force Soft Annealed Cu 37000 PSI


OOOO
0.46
11.684
0.049
0.16072
380
302
125 Hz
6120 lbs


OOO
0.4096
10.40384
0.0618
0.202704
328
239
160 Hz
4860 lbs


OO
0.3648
9.26592
0.0779
0.255512
283
190
200 Hz
3860 lbs


0
0.3249
8.25246
0.0983
0.322424
245
150
250 Hz
3060 lbs


1
0.2893
7.34822
0.1239
0.406392
211
119
325 Hz
2430 lbs


2
0.2576
6.54304
0.1563
0.512664
181
94
410 Hz
1930 lbs



-Bill

BB.

Re: need configuration info..

wie69 wrote: »

16 panels 150wp installed at my roof divided into 2 part.
1 part is 2 series 6 parallel is connect to Outback FM80 so total panel is 12 panels, then the rest is 4 panels i made in parallel to connect built in solar charge controller in inverter side.

so 2 source charger to charge the battery bank 24volt 800amp, what do you think Bill ? is safety using 2 source charger ?

Yes, it can be done safely. You can have parallel charging sources. Just connect them each to your main battery connection. Do not "share" the wires from the battery bank to the various chargers/inverter (each device should have its own wires+fuse/breaker back to the common battery bus--Generally we only put one breaker/fuse in the + lead from the battery bus).

-Bill

wie69

Re: need configuration info..

Hi Bill

base on you chart. i use mm2
from inverter to battery using 2 AWG
from FM80 to Battery Bus Bar using 5 AWG
from PV to combiner box (each string) using 9 AWG (coz here 8 AWG not available).

i use 160amp circuit breaker ABB
250amp flat fuses
500amp dc shunt
other than above is very difficult to get.

my roof cannot be add more solar panels, no more space. its fix 16panels 150wp and 4panels 100wp.

24 volt 3000watt inverter have 3 option to choose for battery priority setting

1. Low trip to bypass 22v and High trip to bypass 28v
2. Low trip to bypass 21v and High trip to bypass 27v
3. Low trip to bypass 20v and High trip to bypass 26v

so i cannot switch to 23volts minimum. 22volts is okay ?

i use outback string sizing tool.
for 24 volt battery bank, i better use 2 series and 6 parallel and array wattage 1804 or 3 series 4 parallel with same array wattage.
for 48 volt battery bank, i better use 2 series and 8 parallel and array wattage 2405 or 3 series 5 parallel (1 panel is not use)

4 panels 100wp i install because have little space. first time i thougth is use for built in scc inverter 3000watt. but is not enough watt to charge 800amp battery.

so what you suggestion Bill ?

using 6000watt inverter or 3000watt inverter for best result that i have 16panels 150wp + FM80 + 8pcs 12volt 200A deep cycle battery.

many thanks for advice

Jon

BB.

Re: need configuration info..

Having fun yet Jon?

wie69 wrote: »

base on you chart. i use mm2
from inverter to battery using 2 AWG
from FM80 to Battery Bus Bar using 5 AWG
from PV to combiner box (each string) using 9 AWG (coz here 8 AWG not available).

i use 160amp circuit breaker ABB
250amp flat fuses
500amp dc shunt
other than above is very difficult to get.

Looks reasonable.

my roof cannot be add more solar panels, no more space. its fix 16panels 150wp and 4panels 100wp.

Do they get "good sun"? Any shading (trees, vent pipes on roof, vents, etc.) of solar panels pretty much kills that panel's (or string's) output.

24 volt 3000watt inverter have 3 option to choose for battery priority setting

1. Low trip to bypass 22v and High trip to bypass 28v
2. Low trip to bypass 21v and High trip to bypass 27v
3. Low trip to bypass 20v and High trip to bypass 26v

so i cannot switch to 23volts minimum. 22volts is okay ?

You have what you have--22 volts is better than the others... I would monitor the battery bank, or even setup a little alarm/red light that turns on when the bank approaches ~23 to 24 volts minimum (usually with a 1-5 minute delay--You do not want the starting of a refrigerator or water pump to give you false alarms).

i use outback string sizing tool.
for 24 volt battery bank, i better use 2 series and 6 parallel and array wattage 1804 or 3 series 4 parallel with same array wattage.
for 48 volt battery bank, i better use 2 series and 8 parallel and array wattage 2405 or 3 series 5 parallel (1 panel is not use)

Use the Outback sizing tool (I do not work for Outback, or any solar business, so I am giving you general guidance regarding the basics--You should do your own calculations/research on your products to ensure that they are correct. It is not my system and I am not there).

As long as the Vmp-array is >~35 volts for 24 volt battery bank and >~70 volts for 48 volt battery bank (using the panel Vmp specifications) you are fine.

If your Vmp-array is >~100 VDC Vmp, then you need to be very careful and use the Outback array sizing tool to make sure that it will safely/reliably work with your weather (you probably do not get sub freezing temperatures in your area--not very cold).

4 panels 100wp i install because have little space. first time i thought is use for built in scc inverter 3000watt. but is not enough watt to charge 800amp battery.

so what you suggestion Bill ?

If your Vmp for the smaller panels is ~17.5 volts--Then you can put two in parallel to match your Vmp for the 150 watt panels of ~35.8 volts (i.e., if you decide on 2* 35.8 panel for 71.6 Vmp-array, then 4x 17.5 volt panels in series = 70 VDC Vmp--Perfectly OK to parallel (with smaller protection fuse) with the other panels).

3x 35.8 panels in series is Vmp-array = 107.4 volts and 3x 42.9 volts = 128.7 volts Voc-array at ~25C... If you have some cold/clear days (near 0C) it could be an issue (maximum FM 80 input voltage is around 140-150 VDC). But that may not be a problem for you.

If you choose the 24 volt battery bank, then the "optimum" choice is probably 2x 35.8 volt panels in series. The maximum array I would suggest would be:

80 amps * 29 volts charging * 1/0.77 panel+controller derating = ~3,013 Watt "cost effective" maximum array

Which is larger than the array you can fit on your roof--So, no reason to worry about more panels later.

using 6000watt inverter or 3000watt inverter for best result that i have 16panels 150wp + FM80 + 8pcs 12volt 200A deep cycle battery.

If you are happy with the 3,000 Watt AC inverter at 24 volts--I would probably just stick with that.

I would look seriously at your energy consumption and see if you can reduce it some--That will help a lot too. Newer appliances (at least in the US) are much more energy efficient.

If you can get a Kill-a-Watt type meter to measure your energy usage per appliance, that will help you understand where to start conserving.

Laptop computers use (in general) a lot less power than older desktop computers. New refrigerators can use 1/2 or less power vs older refrigerators, etc.

A lot of times, it is the old computer left on 24 hours per day that uses more power than the microwave or electric hot plate in the kitchen.

Also, very popular is the "cooking thermos" with Asian immigrants in the US:

http://www.amazon.com/Zojirushi-SN-XAE60XA-Stainless-Thermal-2-Gallon/dp/B004P45ZB6

You quickly boil the food in the metal pot, then drop the pot into the thermos and let it "cook" for 2-4 hours. Can save lots of energy and keep your kitchen cooler.

-Bill

wie69

Re: need configuration info..

hi Bill

many thanks for your advice..

my solar panels directly face to south with 85degree to sun (5degree is for water slide down when rain).
and no shading.

my small 100wp panels specs
vmp : 19.33V
Imp : 5.18A
Voc : 22.91V
Isc : 5.61A

vmp voltage cannot match to 150wp panels even in series.

i think to buy 20A MPPT SCC for charge my backup generator Battery.

i decide to use 3000watt 24volt inverter first.
with your advice using 2x 35.8 volt panels in series.

i will follow outback string sizing tool.
24volt battery bank use 2 series and 6 parallel for outback SCC FM80
and for built in scc i will use 4 parallel

for battery configure to 24volt 800amp

using option 1 on inverter
1. Low trip to bypass 22v and High trip to bypass 28v

if 3000watt not enough, i can swicth to 48volt 6000watt inverter.
with change battery configuration only and 4 panels 150wp add to existing 2 series 6 paralel panels.
little change only..

80 amps * 29 volts charging * 1/0.77 panel+controller derating = ~3,013 Watt "cost effective" maximum array

i can add more panels if my neighbor house sold to me.. my roof really no space anymore..

i will follow your advice to look seriously energy consumption.

i am not lucky as you Bill, my grid company not allow me to use grid tied inverter that i can sold the excess energy.
my goverment made rule very funny, may be Indonesia the one country that electric energy ONLY can be sold to
goverment owner grid company only ( PT.PLN <Perusahaan Listrik Negara>) than goverment grid company only CAN sold to public.

private grid company CANNOT sold the energy to public, MUST sold to goverment grid company. Monopoly...

now goverment grid company in my area have defisit 200 Megawatt.
so every week have 3 or 4 times out of electricity with 4 hours long, sometime twice a day.

using generator is okay, but to noisy and goverment limit public to buy gasoline at gas station.

the rule and out of grid make me headache.. that why i switch to solar energy with grid/generator as backup.

that little story of me..



regards

Jon

BB.

Re: need configuration info..

Good Day Jon,

Government bureaucrats are the same the world over...

In California, it is illegal to even put solar panels on my roof and charge a battery bank that can run my appliances/home. The theory is the utility took out 30 year loans (distribution, generator stations, etc.) based on my home being a customer for the next 30+ years.

If I was to take my home off the grid (or even generate some of my power locally), I would be "stranding" utility assets.

But when the government decides that solar PV systems is the next best thing since sliced bread (an English saying), then they will write a whole set of rules and force utilities to let us use GT solar + net metering and give money out to California home owners to subsidize the installation of GT power.

In general I would suggest that you start with a battery bank + AC inverter + AC battery charger connected to the grid to supply your backup power needs (if that is 4-8 hours for power outages, or if you want as much as 2 days + 50% maximum discharge--That is your choice).

Next, you can add a solar array and/or backup genset to support longer power outages. And, of course, the solar panels can help you reduce power costs.

The problem is that batteries have limited cycle life. In the US, it is difficult to use batteries + solar to save power costs. Because the money you save on power costs, will be lost to the cost of having to replace your batteries more often because the wear out from cycling.

You can make a cost model and see how it works out for you (batteries with ~2,000 cycle life--or whatever yours are rated for).

-Bill

wie69

Re: need configuration info..

hi Bill

BB. wrote: »

In general I would suggest that you start with a battery bank + AC inverter + AC battery charger connected to the grid to supply your backup power needs (if that is 4-8 hours for power outages, or if you want as much as 2 days + 50% maximum discharge--That is your choice).

Next, you can add a solar array and/or backup genset to support longer power outages. And, of course, the solar panels can help you reduce power costs.

-Bill

before i post the thread.
i start with 6000watt inverter 48volt (turn off AC charger) + 400amp battery bank + 8 panels 150wp (2series+4parallel) + FM80
running like home UPS, can be cover my Load with 8 hours if when out of grid, and the rest battery 74% (base on my inverter display).
in bright sun , my battery always full, when rainy whole day, it keep battery 92%.

now after i add 8 panels now total 16panels, i want to make it off grid with grid/genset backup.
thats why i need some advice..
for battery life cycle , yes is to short. but i cannot use grid tie inverter.

Jon

wilsonbh

Re: need configuration info..

I'm researching a grid tie system for my home. My house can only handle 12 and possibly 10 panels. I was excited to see some panels reaching 300w (SHARP).

Any adivice on what setup I'd need for these constraints? I was thinking about a Xantrex 3.3 grid tie inverter and 10 or 12 SHARP panels. I live at zip 32952.

Billy Wilson

jcheil

Re: need configuration info..

wilsonbh wrote: »

I'm researching a grid tie system for my home. My house can only handle 12 and possibly 10 panels. I was excited to see some panels reaching 300w (SHARP). Billy Wilson

Just remember that the more wattage the panel, the LARGER (physically) the panel will be. And those 300+w panels are HUGE! Like 5-6' tall and 3-4' wide.

We have not yet come to a point in engineering/science to get 300w from a panel that is PHYSICALLY the size of a 100w panel.
Mono panels are slightly more efficient (couple of percent) but that only equates to a few square inches smaller than a poly panel.

So saying your house can only handle 10-12 panels is too general of a statement unless we know the physical size of the roof. Plus with the new roof set-back requirements, you will lose available space also.

SkiDoo55

Re: need configuration info..

For panel and inverter selection need to keep in mind that hot days voltage will fall. String array will need to meet minimum voltages to keeps the inverter online. On GT inverter acceptable for most to be over paneled. More panel wattage than rated wattage of inverter. On sizing design tool for Schneider 120% is acceptable, so if you all the panel you can do is @3000 Watt the you could get buy with TX2800 etc.
as I heil stated you need to know your available area that can be used on roof and work out array size and placement my 250W panels are 39" x 64.5" and they get physically bigger in higher wattages plus heavier.

wie69

Re: need configuration info..

yes, more panel wp, more bigger in size.
i have 280wp panel installed at my shop with dimension 195cm x 99.5cm ( 78" x 39.8" )
and 240wp 164.5cm x 99.5cm ( 65.8" x 39.8" )

is GT can use battery for backup ?

Jon

BB.

Re: need configuration info..

Yes, there are inverters that can do that... More or less, they are full off grid inverters (plus battery bank+solar panels+solar battery charger) that can run off grid (back power or even full off grid), and can run in a GT mode where energy from the solar panels/battery charging-floating can be fed back to the utility grid.

So, they are still pretty expensive (basically the price of a full off grid power system--GT systems are much less expensive, no batteries, charge controllers, etc.).

There is a SMA brand/new series that can run a small 120 (or 230) VAC outlet from the solar array only. Sun shining and a 3kW+ (guessing) array and if the utility power fails, you can turn on the ~1,000 watt maximum AC outlet and plug appliances into it.

It only works when the sun is up and pretty bright (the array has to produce >> 1,000 watts to run the outlet).

Is it a marking gimmick or an actual useful feature--I am not sure. If you need 1,000 watts of power in the middle of a sunny day when the grid has failed, then it is probably worth it for you.

-Bill

wie69

Re: need configuration info..

hi Bill

it will be nice if grid tie inverter can use battery for backup when no sun,
any recomended device ?
still need another solar charge controller ?

Jon

wie69

Re: need configuration info..

hi Bill
once again i need to make sure for charging part.

charging from FM80 and built in SCC is different Current Out, but same voltage is SAFETY ?

thanks for advice..

Jon

BB.

Re: need configuration info..

wie69 wrote: »

hi Bill

it will be nice if grid tie inverter can use battery for backup when no sun,
any recommended device ?
still need another solar charge controller ?

Jon

There are some out there... I will give US versions, but they usually have international versions too. And there are certainly many others that I am not aware of:

Magnum Energy MSH4024RE Pure Sine Wave Hybrid Inverter
Conext XW Sine Wave Inverters and Accessories
Radian Series Inverters and Accessories
SMA America Sunny Island

Generator Support is another possibility:

http://forum.solar-electric.com/showthread.php?18459-Demonstration-of-Generator-Support

-Bill

wie69

Re: need configuration info..

hi Bill

at my place always hot climate, when i measure pv voltage on pv disconnect switch is 72volt, but when i connect to FM80 and ready to charge battery bank, voltage fall down to 56-60volt and current going to 20A , it is normal ?

as always hot climate and bright sun, i hear someone said voltage will fall down, if like that, should i make pv 3 series ?

Jon

BB.

Re: need configuration info..

When the battery needs a lot of charging current (say less than 80% state of charge), the FM 80 will be in "bulk mode" charging and drawing maximum energy from the array.

The current will represent the amount of sun the panel is getting (100% of Imp-array) is ~1,000 Watts per sqmeter full sunlight.

The Vmp-array will be measure/calculated by the FM 80... The cells at ~25C will be at Vmp standard temperature conditions (i.e., Vmp from the specification sheet). When the cells become hot (as expected when a black panel sits in hot/direct sun), more or less the Vmp-array can fall by upwards of 20%. So a 70 Volt STC Vmp array (two panels in series) will be down around 56 volts on very hot/sunny days. Cooler days will have a higher Vmp.

Once the battery is over ~80-85% state of charge, the controller will go into "bulk mode" and start cutting back on charging current... And the array voltage will start to rise. Once the battery bank is fully charged and the FM 80 is no longer drawing current, the array will be at Voc (again, actual Voc will be temperature dependent).

-Bill

wie69

Re: need configuration info..

hi Bill
if like that, my solar charge is working normal,

thanks bill for explanation..

Jon

wie69

Re: need configuration info..

hi Bill

i want to setup FM80 Aux mode Low Batt Disconnect in 48volt battry bank.
what your suggestion for low voltage and delay time for disconnect trip.
and reach voltage and delay time for reconnect trip.

i want to use dc relay to controll ac grid.

Jon

BB.

Re: need configuration info..

I don't really know about the details of the Outback to give you any help here... I would be following the manual.

Perhaps somebody else can give you the details.

-Bill

Cariboocoot

Re: need configuration info..

Buy an Outback inverter and use its LVD to switch to grid power. Much simpler and more likely to work than attempting to rig a relay capable of handling the AC input and driving it off the AUX port of the FM80. For one thing the AUX port will not drive a very large relay, so you'd end up with two relays. More wire, more complexity, more power needed to run the triggers.

wie69

Re: need configuration info..

hi,

forget setting on fm80, i just want to know how much lower voltage need to charge 48volt battery bank,
to keep long life AGM type battries

JON