Don B. Cilly
Energetic energy padawan
Right, but "rated watts" does not necessarily equal "good charge", does it? :·)
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Hi, first post. Can anyone recommend a budget 3kw inverter/charger to run 2 fridges. Petrol $4.50 per lt. Generator is now to expensive to run for 8hr
- Thread starter Nroprb
- Start date
Thanks Michael and Hedges. Have decided on a 24v system run during the day and ice bottles in the fridge at night.
Epever 2000w U Power
4 x 400w Hyundai S400VG 38.6V 10.38A
2 X 100 AH Fullriver to start with. See if they will suffice or have to get 2 more at $1100.
Have a couple more questions please.
If I do have to add 2 more batteries can I add different brands with the same AH ?
Cable size from my 2 x 100 ah batteries to my 2000w inverter, the size of the circuit breaker between them and whether I need to install a fuse also on the + lead close to the battery?
Epever 2000w U Power
4 x 400w Hyundai S400VG 38.6V 10.38A
2 X 100 AH Fullriver to start with. See if they will suffice or have to get 2 more at $1100.
Have a couple more questions please.
If I do have to add 2 more batteries can I add different brands with the same AH ?
Cable size from my 2 x 100 ah batteries to my 2000w inverter, the size of the circuit breaker between them and whether I need to install a fuse also on the + lead close to the battery?
Also could you confirm as my PV output is 10.36A that a 15A circuit breaker between the panels and 2000w U power will suffice?
And as the PV panels are going to mounted on a skillion roof will it matter if the roof slops away from the sun by 7 degrees, as it will be hard to mount them inclined because they will be in a 2 x 2 pattern.
And as the PV panels are going to mounted on a skillion roof will it matter if the roof slops away from the sun by 7 degrees, as it will be hard to mount them inclined because they will be in a 2 x 2 pattern.
MichaelK
Solar Wizard
A lot of people confuse daylight with sunhours. A sunhour is somewhat of an abstraction to describe the relative amount of power you are getting, related to latitude and season. When Hedges mentions "5 effective hours sunshine might be average, and 2 hours in winter", I believe he is referring to sunhours. It's just a kind of shorthand to quickly determine what you are likely to make in kWh in a day.
In your case, with getting ~50% or panel rating for 8 hours, thats saying you are getting ~4 sunhours.
Hedges
I See Electromagnetic Fields!
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PV panels can produce more than Isc under some illumination conditions. OCP between PV panels and SCC should be at least 1.56x Isc. (That's 1.25 x 1.25)
OCP between SCC and battery should be at least 1.25x SCC max output current.
That's assuming thermal OCP, like fuse or thermal/magnetic breaker. If thermal/hydraulic, some claim they can be operated continuously at 100% not just 80% of rating, so one fewer 1.25x factor could be used.
But the whole point of OCP is to never blow/trip unless there is a short.
Single series string (implied by the current figures you quote) doesn't actually require PV breaker. Nor does two parallel. But convenient for disconnect. I would prefer 2-pole breaker isolating both PV+ and PV- before working on wires.
Sloped 7 degrees away from South would be OK middle of the summer. Don't plan on much yield in winter. Optimal tilt for maximum year-round yield is same as your latitude. If your needs are more in summer or more in winter, then a different tilt helps.
Four panels - what array configuration? 4p? 4s? 2s2p?
If 4p or 2s2p, you could tilt up two panels to catch more sun when lower in the sky.
Fullriver - AGM? All should be same age, and identical. If not all fully charged, they degrade. If one lower voltage than other (e.g. due to chemistry), it drags down others.
(Lithium, apparently OK to add more later. Different batteries may supply different percentage of current.)
www.upsbatterycenter.com
2000W / 20V / 90% x 1.12 x 1.25 = 156A minimum fuse recommended
20V low battery
90% inverter efficiency
12% ripple factor (RMS vs. mean current drawn from battery for sine wave inverter)
25% margin to avoid nuisance blowing.
2/0 cable is usually good to use. Can never be too heavy, unless it doesn't fit in terminals.
Otherwise, look up ampacity charges for whatever fuse you use (e.g. 150A, 200A.)
OCP between SCC and battery should be at least 1.25x SCC max output current.
That's assuming thermal OCP, like fuse or thermal/magnetic breaker. If thermal/hydraulic, some claim they can be operated continuously at 100% not just 80% of rating, so one fewer 1.25x factor could be used.
But the whole point of OCP is to never blow/trip unless there is a short.
Single series string (implied by the current figures you quote) doesn't actually require PV breaker. Nor does two parallel. But convenient for disconnect. I would prefer 2-pole breaker isolating both PV+ and PV- before working on wires.
Sloped 7 degrees away from South would be OK middle of the summer. Don't plan on much yield in winter. Optimal tilt for maximum year-round yield is same as your latitude. If your needs are more in summer or more in winter, then a different tilt helps.
Four panels - what array configuration? 4p? 4s? 2s2p?
If 4p or 2s2p, you could tilt up two panels to catch more sun when lower in the sky.
Fullriver - AGM? All should be same age, and identical. If not all fully charged, they degrade. If one lower voltage than other (e.g. due to chemistry), it drags down others.
(Lithium, apparently OK to add more later. Different batteries may supply different percentage of current.)
FULLRIVER HGL100-12B 12V 100Ah Battery with M8 - Insert Terminals
FULLRIVER HGL100-12B 12V 100Ah Battery. High quality fresh new replacement for the FULLRIVER HGL100-12B 12V 100Ah battery. 1 Year Warranty included!
2000W / 20V / 90% x 1.12 x 1.25 = 156A minimum fuse recommended
20V low battery
90% inverter efficiency
12% ripple factor (RMS vs. mean current drawn from battery for sine wave inverter)
25% margin to avoid nuisance blowing.
2/0 cable is usually good to use. Can never be too heavy, unless it doesn't fit in terminals.
Otherwise, look up ampacity charges for whatever fuse you use (e.g. 150A, 200A.)
Don B. Cilly
Energetic energy padawan
I would say I get (on a sunny day) 40% for half an hour, 50-60 for an hour, 80-85% for 5 hours, 100% never (of rated power, eh) and then again 50-60 and 40, tapering to zero. By 12-1PM the batteries are usually full anyway.
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MichaelK
Solar Wizard
The really best way to determine this empirically is to just count up the total number of kWh of power you made that day, and divide by the total number of watts of panels.
The problem is that once the battery is full, you stop making watts. The last time I was able to do this was when I was commissioning my new workshop battery bank, when I only had one 1000W array online. So, the new battery was sucking up every watt available. With a rotating 1000W array optimally angled to the sun, I found I made 5.1kWh of power on Feb 8th, by rotating the frame East to West over the course of the day.
So, I could say that I had 5.1 sunhours (sh) on Feb 8th because of solar tracking. I would guestimate that it would have been closer to 3sh if I had just left the array facing south.
Another way you could accomplish this is to turn on a load just slightly larger than your array, and determine the watts coming in at 8am, 9am, 10am, ect. over the course of the day. Then just add up all the hourly watt reading over the course of the day to approximate your total production. Won't be 100% accurate, but I think you can get a number with 5-10% of the real sh.
Don B. Cilly
Energetic energy padawan
Yeah well, but I don't care, and why should I? :·)
I don't really need to determine anything. I have a (big, analog) ammeter, a digital voltmeter and a kill-a-watt staring me in the face all day.
I stare back quite a bit, I like it. I know what the panels and batteries are doing. I don't try to squeeze every possible amp out of the PV, because I have plenty. My batteries are tip-top (LFP), my panels are really quite good (a motley ragamuffin crew of mongrels, but good ones), I don't bother with series because I sort of vaguely dislike high voltages.
Once the batteries are full, I stop making watts, sure. As Miles Davis would say... ;·)
Actually, once they're full is when I start the washing machine, breadmaker, etc.
Advantages of low-draw, plenty-of-power off-grid mode :·)
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I don't really need to determine anything. I have a (big, analog) ammeter, a digital voltmeter and a kill-a-watt staring me in the face all day.
I stare back quite a bit, I like it. I know what the panels and batteries are doing. I don't try to squeeze every possible amp out of the PV, because I have plenty. My batteries are tip-top (LFP), my panels are really quite good (a motley ragamuffin crew of mongrels, but good ones), I don't bother with series because I sort of vaguely dislike high voltages.
Once the batteries are full, I stop making watts, sure. As Miles Davis would say... ;·)
Actually, once they're full is when I start the washing machine, breadmaker, etc.
Advantages of low-draw, plenty-of-power off-grid mode :·)
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Don B. Cilly
Energetic energy padawan
Still, I can't quite get my head around this:
According to Mother G., current petrol prices in NZ are around $2.8 (NZ) per litre - roughly $2 US.
So I just wonder how they get away with $4.50 in the small town nearby. :·)
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According to Mother G., current petrol prices in NZ are around $2.8 (NZ) per litre - roughly $2 US.
So I just wonder how they get away with $4.50 in the small town nearby. :·)
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2000W / 20V / 90% x 1.12 x 1.25 = 156A minimum fuse recommended
Thanks again Michael ?. Could you please advise whether I should put a 200 amp or 300 amp breaker between the batteries and inverter?
Also the 20V mentioned above, where does that come from as I will have a 24V system?
As this breaker is what I will be turning off when I am not there do I also have to isolate the negative lead also?
Thanks again Michael ?. Could you please advise whether I should put a 200 amp or 300 amp breaker between the batteries and inverter?
Also the 20V mentioned above, where does that come from as I will have a 24V system?
As this breaker is what I will be turning off when I am not there do I also have to isolate the negative lead also?
MichaelK
Solar Wizard
I believe that Hedges is referring to the fact that as the battery is drained, the voltage drops, then the inverter starts drawing more amps to compensate. This creates a runaway feedback loop that could result in dangerous amp draws if there was not a built-in low-voltage cuttoff.
In my case, I purchased a brand-specific power center to integrate my inverter/controller, which had a 250A breaker specifically for the XW+. I did the same thing for my 24V workshop system(also 250A). With my SW4024 inverter, I bought this power center, which already incorporates the breakers.
ressupply.com
Keep in my though that these products only get made for the tier-1 components. You might not find the corresponding panel designed for economy inverters, though you are likely to juryrig something. It just won't look pretty.
For both my systems, I've only breakered the positive leads, never also the negatives.
In my case, I purchased a brand-specific power center to integrate my inverter/controller, which had a 250A breaker specifically for the XW+. I did the same thing for my 24V workshop system(also 250A). With my SW4024 inverter, I bought this power center, which already incorporates the breakers.
Schneider Electric 865-1016 Conext SW DC Breaker Panel - RES Supply
Free Shipping! Schneider Electric 865-1016 Conext SW DC Breaker Panel, Includes 250A Breaker, RNW8651016
ressupply.com
For both my systems, I've only breakered the positive leads, never also the negatives.
Hedges
I See Electromagnetic Fields!
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I'm not the archangel. Maybe the "other" one.
You said, "100 AH Fullriver" which appears to be an AGM battery. Under load, a 12V nominal battery reaches about 10V (so inverter has to pull more current to maintain power output.) For someone using LiFePO4 it looks like 12V is about minimum per 12V battery.
electronics.stackexchange.com
By my calculation, 156A is sufficient, so 200A fuse would be preferable over 300A.
It is normal to just interrupt positive side of battery. For 24V, I don't think there is even a code requirement to ground negative side (would be at higher voltages.)
For PV, which in my case is 480Voc, I like to interrupt both positive and negative before working on it.
You said, "100 AH Fullriver" which appears to be an AGM battery. Under load, a 12V nominal battery reaches about 10V (so inverter has to pull more current to maintain power output.) For someone using LiFePO4 it looks like 12V is about minimum per 12V battery.
Designing a battery capacity monitoring system for AGM lead acid battery
I would like to design a battery capacity system for my AGM lead acid battery (12v, 40Ah). My idea is that I have values of the battery voltage and its corresponding capacity, which I will use to p...
electronics.stackexchange.com
By my calculation, 156A is sufficient, so 200A fuse would be preferable over 300A.
It is normal to just interrupt positive side of battery. For 24V, I don't think there is even a code requirement to ground negative side (would be at higher voltages.)
For PV, which in my case is 480Voc, I like to interrupt both positive and negative before working on it.
timselectric
If I can do it, you can do it.
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Also
NEC requires all DC ungrounded conductors in a circuit, be opened by a common handle in the disconnect.
NEC requires all DC ungrounded conductors in a circuit, be opened by a common handle in the disconnect.
Thanks again Michael and Hedges. Could you please explain how you would set up my solar panels ( 4 x 400w, Maximum Power Voltage 38.6V and Maximum power Current 10.36A )
I have 2 options
In series-parallel I will be getting 77.2V and 20.72A
If I run in Parallel I will be getting 38.7V and 41.44A
My Upower2000 has a max 30A charger and a Max PV open circuit voltage of 100V (at minimum operating temperature) and 92V (at 25 degrees environment temperature)
The PV has an open circiut voltage of 46.4V so please correct me if I am wrong, in series-parallel that would make 92.8V which is just over the maximum PV open circuit voltage at 25 degrees.
Will that be ok as I doubt that I will be getting 100% efficiency.
Could you please let me know should I wire up in series-parallel or just Parallel and why.
Last piece of my puzzle
Kind regards
I have 2 options
In series-parallel I will be getting 77.2V and 20.72A
If I run in Parallel I will be getting 38.7V and 41.44A
My Upower2000 has a max 30A charger and a Max PV open circuit voltage of 100V (at minimum operating temperature) and 92V (at 25 degrees environment temperature)
The PV has an open circiut voltage of 46.4V so please correct me if I am wrong, in series-parallel that would make 92.8V which is just over the maximum PV open circuit voltage at 25 degrees.
Will that be ok as I doubt that I will be getting 100% efficiency.
Could you please let me know should I wire up in series-parallel or just Parallel and why.
Last piece of my puzzle
Kind regards
Hedges
I See Electromagnetic Fields!
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Some equipment has these two specs, max voltage at minimum temperature and max voltage at 25 degrees. I'm not sure the electronics actually has a reduced voltage at ambient as compared to cold; they may be trying to guide you to not going over-voltage under cold conditions.
1) What is the historical coldest temperature on record for your location?
2) From PV panel data sheet, what is temperature coefficient of Voc?
From those, we can calculate whether panels wired 2s would exceed 100V.
30A probably refers to boosted output current to battery, not input current from PV. (unless that was PV spec max input current)
What is your battery voltage, 12V or 24V?
4 x 400W / 24V = 67A
That is significantly over-paneled. Look for a max Isc spec on inverter, see if you exceed it.
By orienting two panels towards AM sun and two towards PM sun (SE and SW for those of us in Northern hemisphere), peak power can be reduced to about 0.7 as much, 47A current. Still considerably over-paneled.
I like wiring 2s2p for smaller gauge wire and less IR drop, although 4p (which should have a fuse per panel) looks like still high enough voltage for battery.
Assuming your battery can accept the current, adding a second SCC might make use of all the PV.
Hi Hedges, coldest temperature in the last 10 years is 15 degrees C. Also the PV charge is 30A as well as the utility charge of 30A.
I just don't understand whether it is better for me to go parallel or series-parallel. I know I am close to max voc but what is best as explained the new epever upower can power the inverter aswell as charge the battery. This hybrid does not even need a battery. So my question is if it was you bach how would you power it and am I to clos to max voc. The upower does have an overload for max voc. I want to use series-parallel and monitor it then can try parallel. But was hoping you could explain what would be best and why.
Thanks
Does the inverter take amps or voltage
I just don't understand whether it is better for me to go parallel or series-parallel. I know I am close to max voc but what is best as explained the new epever upower can power the inverter aswell as charge the battery. This hybrid does not even need a battery. So my question is if it was you bach how would you power it and am I to clos to max voc. The upower does have an overload for max voc. I want to use series-parallel and monitor it then can try parallel. But was hoping you could explain what would be best and why.
Thanks
Does the inverter take amps or voltage
Hedges
I See Electromagnetic Fields!
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Still need temperature coefficient of Voc from PV panel data sheet, to determine max voltage.
Oh, right. AGM.
Do you have info on desired charge rate?
My model of AGM wants 0.2C, so 200A x 0.2 = 40A.
Excessive charge rate would cause loss of electrolyte and ruined battery.
Should probably be able to take much higher current for a short time (e.g. automotive starting applications with brief high current recharging from alternator.)
If your inverter will charge no more than 30A, even if both PV and utility available, that is probably good. If it can reach 30A + 30A = 60A (not likely), it may or may not be OK, see battery spec.
Over-paneled with SCC limiting charge current to 30A should be good for a steady charge until full.
However, any loads on the inverter will take some of that.
Make sure battery will always get fully charged and sit at absorption voltage for a couple hours every day. By not over-discharging and by fully recharging they will last longer.
Series PV rather than parallel can avoid requirement of fuses (needed if more than 2 PV panels in parallel) and reduce IR loss in wire. You have so much excess power that loss doesn't matter. Just need to stay above minimum MPPT voltage and below max voltage.