I recently purchased 4 540 watt panels and would like to wire them in series and purchase a 6KW 120/240volt hybrid all in one mppt charge controller. Large loads will be mr cool 130vac mini split and blomberg 240vac apartment sized washer and dryer set. My question is will the open circuit current rating on these allow for a 48V system? I am worried 49.6 wont allow a full charge on batteries? Specs on the panels posted. Novice here any advice appreciated.
2200watts should i go 48volt?
- Thread starter zachdc13
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Yes it will provided you place 2 panels in series to create ~100 volts. I would make 2 sets like this and parallel those sets. Like you said if you just parallel the panels you wont have a high enough voltage.
Won't that yield only 24volts though?
if you put the cells in series it will double the volts . I did misread and quote the open circuit voltage not the operating voltage of around 42 so in series you will have 84 volts from each set and then in parallel you will double the amps.
So I am confused could I yield a 48volt system then? Or just 24volt?
Hedges
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Read the specs of the hybrid inverter you're considering. It should list an MPPT voltage range, and absolute maximum Voc (panels will deliver higher voltage in freezing conditions.)
Typically Voc limit may be 100V, 150, 250, 450, 600V depending on model.
You may be able to connect all four panels in series "4s", or just two "2s2p", depending on the voltage limit.
You could certainly get by with lower voltage e.g. 24V if only 2200W, but 48V is how most large home systems are done, and allows more expansion.
Select and price out battery as well.
Typically Voc limit may be 100V, 150, 250, 450, 600V depending on model.
You may be able to connect all four panels in series "4s", or just two "2s2p", depending on the voltage limit.
You could certainly get by with lower voltage e.g. 24V if only 2200W, but 48V is how most large home systems are done, and allows more expansion.
Select and price out battery as well.
rodrick
Free energy enthusiast
Take each panels voltage (voc) and add them together when hooked in series when hooked up in parallel you add the amps of each panel
If I go 24volt hybrid mppt could I just bypass it for 240volt and only run the dryer on shore or generator? I bought a house electric panel with two 30amp breaker for each phase, problem is the 120/240 comes out the controller before going to the breaker box? I am very new to this I just need someone to explain whether those panels will work with a 48volt hybrid mppt and battery bank or not?
rodrick
Free energy enthusiast
Short answer is yes wired correctly
Tomthumb62
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Yes you can create a 48v system, if you wire two panels (or more) in series.
Depending upon your MPPT specs, you may be able to wire more than 2 in series. But you must NOT exceed the input volts for the MPPT. For example, if your MPPT can accept 300V input, you cannot wire panels in series that would exceed or get too close to that. If you do, poof, the magic smoke comes out of your MPPT and you must replace it.
In that example, if you intend to input more than about 250V, you will want to use a temperature calculator to make sure that cold weather wouldn't cause you to exceed 300V. Cold temps will cause solar panels to produce higher voltage.
Use the open circuit voltage (Voc) in your calculations for voltage.
Since you have four panels, you could do one of these two configurations:
1) 2s2p: Two panels wired in series, then another two wired together in series. Then wire the two sets in parallel. This will give you about 100v and 26A. Actual output would be more like 84v and 26A, but use the 100v as a safety measure to not exceed your MPPT input.
2) 4s: Wire all four panels in series. This will give you about 200v and 13A. Actual output would be about 168v and 13A, again use the 200v number as a safety margain to not exceed your MPPT input.
The first option would require thicker cabling, due to the higher amps. Each has it's pros and cons. 4s would be fine if you don't have any shading issues. In ideal conditions, both configurations will produce about the same amount of power.
Tomthumb62
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Not sure if this is part of what's confusing to you, but something that took me awhile to wrap my head around was how can the MPPT take higher voltage but output the (correct) voltage for your system. Such as, how can you put 200v into an MPPT and get 48v out of it?? And how come you can't put 36v into the MPPT and not get 48v out of it. Short answer is MPPT's can "convert" excess voltage into more amps, but if it doesn't have enough voltage to begin with for the given system voltage (system voltage typically 12v, 24, 48v), it can't convert amps into more volts. Hope that makes sense.
What are the specs of the MPPT you are looking at?
What are the specs of the MPPT you are looking at?
Hedges
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Don't think that a "24V" PV panel is only for 24V systems and won't work for 48V system.
That used to be the approach with PWM charge controllers, which simply connect PV panel to battery for charging, disconnect when battery voltage gets too high. MPPT charge controllers operate with higher voltage PV, and multiple PV panels in series deliver higher voltage.
For AC, transformers change voltage. Old inverters, for instance, used transistors to switch 12VDC battery voltage to 12VAC square wave and put it through a transformer to produce 120VAC square wave. High frequency transformerless inverters create pulsed DC which is put through an inductor to make 120/240V sine wave AC. Operating at several kHz instead of 60 Hz, the magnetic components are smaller, lighter, less expensive.
Most charge controllers today are MPPT (Maximum Power Point Tracking), which use transistors to switch higher voltage DC (e.g. 50V to 600V) PV into AC or pulsed DC, and put it through a transformer or inductor to convert it to 24V or 48V DC at higher current.
As Tom said, (most) MPPT can only drop high voltage from PV panels to low voltage for battery. There are some hybrids (charge controller & inverter) which might also boost voltage. But usually PV array is designed with several panels in series such that even on a hot day, maybe with shade on some panels, Vmp remains above highest battery voltage.
That used to be the approach with PWM charge controllers, which simply connect PV panel to battery for charging, disconnect when battery voltage gets too high. MPPT charge controllers operate with higher voltage PV, and multiple PV panels in series deliver higher voltage.
For AC, transformers change voltage. Old inverters, for instance, used transistors to switch 12VDC battery voltage to 12VAC square wave and put it through a transformer to produce 120VAC square wave. High frequency transformerless inverters create pulsed DC which is put through an inductor to make 120/240V sine wave AC. Operating at several kHz instead of 60 Hz, the magnetic components are smaller, lighter, less expensive.
Most charge controllers today are MPPT (Maximum Power Point Tracking), which use transistors to switch higher voltage DC (e.g. 50V to 600V) PV into AC or pulsed DC, and put it through a transformer or inductor to convert it to 24V or 48V DC at higher current.
As Tom said, (most) MPPT can only drop high voltage from PV panels to low voltage for battery. There are some hybrids (charge controller & inverter) which might also boost voltage. But usually PV array is designed with several panels in series such that even on a hot day, maybe with shade on some panels, Vmp remains above highest battery voltage.
If you are looking at a 6kW inverter that is actually what controls the voltage selection for the battery. They will all be 48V, and likely need at least 15kWh of battery to operate properly. Then, as others have stated, you need to wire the PV array to meet the inverter's minimum and maximum Voc limit.
The back side of the math though is if you are using 15kWh/day (or a more reasonable limit of 10-12kWh), you are going to need a minimum of 5 hours of full sun to fully recharge the pack each day, which isn't going to happen in the winter in Canada; 4kWh is more likely.
The back side of the math though is if you are using 15kWh/day (or a more reasonable limit of 10-12kWh), you are going to need a minimum of 5 hours of full sun to fully recharge the pack each day, which isn't going to happen in the winter in Canada; 4kWh is more likely.
Looking at this 6kw mpp all in one 120/240
The next comment mentions I would need 15kwh of battery. I plan on having 4 bms protected lifepo around 270AH each not sure how to convert that to KWh
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Tomthumb62
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That’s about 3.4kWh of battery, at 48v. So that’s four 3.4kWh 12v batteries wired in series to get your 48v.
Assuming 4 sets of 16s 270Ah batteries it is 270x48x4 = 52kWh
That would be too much battery for your PV.
Bluedog225
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It’s good you are here asking questions.
You will be way ahead if you develop a better understanding of the above stuff before you buy the inverter, battery, or even the panels.
At the end of the day, you are probably going to want a few 48 volt “rack” batteries and an all in one inverter. If you go down the individual 12 volt batteries wired together path, it‘s harder.
Go look at some Will Prowse videos. He has several on building a complete system like you want. Grid connected or not. Read some reviews of Signature Solar. And then have a look at Currentconnected.com. Both have ”systems” that will show you good examples of how this stuff comes together.
You will be way ahead if you develop a better understanding of the above stuff before you buy the inverter, battery, or even the panels.
At the end of the day, you are probably going to want a few 48 volt “rack” batteries and an all in one inverter. If you go down the individual 12 volt batteries wired together path, it‘s harder.
Go look at some Will Prowse videos. He has several on building a complete system like you want. Grid connected or not. Read some reviews of Signature Solar. And then have a look at Currentconnected.com. Both have ”systems” that will show you good examples of how this stuff comes together.
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Tomthumb62
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I was assuming he was starting with 12v batteries, but you're correct assuming 48v.
I was thinking 4 12volt wires in series but the 48 v rack batteries seem like a better option, do you think a Powerwall is even better? So 100ah 48volt batteries is equivalent to how many AH in a 12V battery?
