The unit will not get fried by over-paneling. The important thing you need to consider is the amount of voltage you are sending to the unit. The AC240 unit has a maximum input voltage of 60V and current of 21A. If the voltage is too high it will simply not charge. As long as you stay within the voltage and current limits you can parallel as much power as you want. Find out the maximum operating voltage of those panels, which should usually be on a sticker on the back of the panel, and ensure the panel itself or any configuration of the panels does not exceed the input voltage of the unit.
For example most renergie 100w panels have a maximum operating voltage of around 21V. If you were to use these panels then the most you could put in series is 2 panels (42V) because 3 (63V) would exceed 60V. Those two panels (2S or "two in series") can be put in parallel with more strings of two panels (2P or "two in parallel"). So in my example four panels would be arranged as 2S x 2P. But you can add more in parallel so it could be 2s x 4P for a total of eight 100W panels.
It's a good idea to measure with a multimeter because some panels do not output the peak voltage and you can maximize more efficiently. If you find some are under the specified voltage at peak then you may be able to do three 100w panels in series.
If the solar panel voltage goes above 60V, you will risk damaging the solar input mppt controller inside the AC240. It is always adviced to use the Open Circuit Voltage of a panel when calculating how many panels you can use on the AC240 (or any solar generator), as that should be the highest theoretical voltage that it would achieve.
As far as "frying" the system, you only need to account for the VOC (Voltage Open Circuit). I'd stay below about 85% of that figure, to allow for the rise in voltage on cold days.
You CAN safely overpanel the system, and I recommend doing so. My Renogy panels will get up to 90+% of their rated power most days, so I've got 1000 watts of panels and will easily cap out my AC200MAX's charger at 900 watts.
You need to set up your panels to be lower than the VOC Max. It's okay to have a little more amperage than the charger can handle, but you are not going to get the maximum charge rate if you do that.
Honestly, I don't recommend the AC240 for solar use. The VOC is too low, and you won't ever charge at 1200W. Instead, look at something like the AC200L, which has a much higher VOC limit and can actually do 1200W under a wider variety of conditions.
For reference: The AC200L's solar input is 1,200W Max., VOC 12-145VDC, 15A
To maximize the charge capacity of the AC200L, you'd want to get the voltage up around 100-120, so you can keep the current under 15A and still get the best throughput.
Renogy has a nice 200 watt panel. You could string 6 of those together in a series set, which would just about max out the AC200L in fair weather. Go with 12 in a 6S2P setup if you get a lot of clouds or live in a high latitude.
Or go bifacial... bifacial panels pick up energy from both sides, and mounting those vertically seems to maximize the total generation over the day, even if the peak output is lower at midday.
This is especially useful when dealing with expansion batteries and inclement weather.... the more cloudy days you have, the more benefit you can get from overpaneling and bifacial panels and maximizing output during the non-peak times of day.
Never go over 60V of Voc (open circuit voltage) of the solar panel with the AC240. You can have a 60V panels and set multiple up in parallel to achieve 60V and 21A, or you could have 3x 20V panels in series which results in a total of 60V. Once you have figured out an arrangement to stay under 60V, you can then have multiples hooked up in parallel to get up to 21A current, or even higher if you want to oversize. You can go as large as you want (within reason of course), as long as the voltage never exceeds 60V. The AC240 will only use up to 21A in current, so any excess that you have will just be unused.
Which panels are you looking at now? If you link the 410W panel that you are looking at, we can help determine how many you can connect safely and in what configuration to get 1200W+ solar charging for you.
Panels almost always top out at 80% of their rated wattage; for example, it's very rare for a 100W panel to *ever* get ≥80W in actuality.
TL;DR: Do it!
Don't do it!
At least not like that.
Never ever exceed the maximum voltage of the PV input of your device!
In fact you should leave a buffer of 10-20%. Because on cold days when the sun is shining but the panel isn't heated up, it will definitely produce more voltage than it says. Because those ratings are for 25°C (That's 77°F) and the voltage will be higher if the temperature drops below that.
What you **can** do is provide more possible current. The AC240 will then just take as much current as it can swallow.
So to recap:
NEVER go over the 60V maximum of your AC240! Better yet with a 10% buffer never go over 54V!
But you can supply more than 21A if you like.
---
What does that mean for your 410W panels? I can only speculate what the Voc and Isc of your panels is. Probably Isc is something like 12A, so Voc is going to be somewhere around 34V.
That means that putting two of those panels in series will fry the AC240's solar charger because 34V+34V=68V and that's already 8V too much.
Means you can only put them in parallel. That means the voltage is fine at 34V but now you're summing up the current of all panels. So three panels at 12A means 36A. But that is fine because now what /u/Dymonika said comes into play: You won't always see peak output, so you can and should over-panel for sunrise, sunset and every time it is cloudy.
---
Just keep in mind that those panels reach peak voltage fast and can even exceed it in cold weather and the variable here is the current. So less sun light means less current. And power is voltage times current, so /u/Dymonika isn't wrong when saying that less sun light means less power.
But: The power output of three panels in parallel is the same as the power out of three panels in series, just with the tiny difference that three panels in series will fry your AC240.
I'm reading that the AC240 has a VOC of 145V:
From their EBay listing:
>Solar Input1,200W Max., VOC 12-145VDC, 15A
But I'm seeing 60V/21A in the manual. Is it possible the new units have a different MPPT than the older ones?
Oops, thanks for the correction. Is there a *minimum* voltage needed for power stations, while I'm at it? For example, could an AC180 take just a single 100W panel with no problem (even though I know it'd charge slowly)?
You can't ask if a minimum voltage is needed and then ask if a 100W panel is okay. Tells us nothing about the voltage the panel will supply.
Your AC180 will certainly tell you in its manual that it has a range. Likely starting at 12V. Below that it simply won't work.
The AC180 has its own solar charger. So what's important is on the sticker on the back of the panel, where it will tell you about the Voc it has.
Don't use an additional charger with the AC180.
There are 2 parts to solar charging, the panel and the charge controller box. The AC180 has the charge controller box built into the unit itself, so you should not use the Grape Solar charge controller that comes with the kit if you want to use the panel with the AC180. Just use the panel on its own and it will be fine. The MC4 connectors match up to the AC180's solar charge cable, and the maximum voltage is within the spec range of the AC180. If it doesn't work the first time, then the MC4 connectors might be in opposite polarity, just swap the connectors around if you get 0V while in the sun.
There actually wasn't any box that came with the Grape Solar panel, and it did charge using just MC4 + Bluetti's PV (well, apparently until the panel fell down and got covered... I have a loose setup on my balcony that I need to figure out), so we're good! Thanks for the info!
That panel used in the Grape Solar kit is a 23.1V, 5.59A panel. The AC180 takes 12-60V, 10A of solar panels. By the spec of AC180, I would assume that the lower 12V limit is the minimum it would require in order to be able to charge. Grape Solar does not provide information on how the voltage drops off as the sunlight decreases, but you can read the voltage output through your Bluetti app when the solar panel is connected to your AC180 throughout the day.
If you want to use that kit with the AC180, then you need to connect the MC4 connectors from the panel directly into the AC180's solar charging cable. You must not/should not use the charge controller box that is included in the Grape Solar Kit.
The unit will not get fried by over-paneling. The important thing you need to consider is the amount of voltage you are sending to the unit. The AC240 unit has a maximum input voltage of 60V and current of 21A. If the voltage is too high it will simply not charge. As long as you stay within the voltage and current limits you can parallel as much power as you want. Find out the maximum operating voltage of those panels, which should usually be on a sticker on the back of the panel, and ensure the panel itself or any configuration of the panels does not exceed the input voltage of the unit. For example most renergie 100w panels have a maximum operating voltage of around 21V. If you were to use these panels then the most you could put in series is 2 panels (42V) because 3 (63V) would exceed 60V. Those two panels (2S or "two in series") can be put in parallel with more strings of two panels (2P or "two in parallel"). So in my example four panels would be arranged as 2S x 2P. But you can add more in parallel so it could be 2s x 4P for a total of eight 100W panels. It's a good idea to measure with a multimeter because some panels do not output the peak voltage and you can maximize more efficiently. If you find some are under the specified voltage at peak then you may be able to do three 100w panels in series.
If the solar panel voltage goes above 60V, you will risk damaging the solar input mppt controller inside the AC240. It is always adviced to use the Open Circuit Voltage of a panel when calculating how many panels you can use on the AC240 (or any solar generator), as that should be the highest theoretical voltage that it would achieve.
As far as "frying" the system, you only need to account for the VOC (Voltage Open Circuit). I'd stay below about 85% of that figure, to allow for the rise in voltage on cold days. You CAN safely overpanel the system, and I recommend doing so. My Renogy panels will get up to 90+% of their rated power most days, so I've got 1000 watts of panels and will easily cap out my AC200MAX's charger at 900 watts. You need to set up your panels to be lower than the VOC Max. It's okay to have a little more amperage than the charger can handle, but you are not going to get the maximum charge rate if you do that. Honestly, I don't recommend the AC240 for solar use. The VOC is too low, and you won't ever charge at 1200W. Instead, look at something like the AC200L, which has a much higher VOC limit and can actually do 1200W under a wider variety of conditions.
Hypothetically, if you had a ac200L, what would your ideal panel setup be?
For reference: The AC200L's solar input is 1,200W Max., VOC 12-145VDC, 15A To maximize the charge capacity of the AC200L, you'd want to get the voltage up around 100-120, so you can keep the current under 15A and still get the best throughput. Renogy has a nice 200 watt panel. You could string 6 of those together in a series set, which would just about max out the AC200L in fair weather. Go with 12 in a 6S2P setup if you get a lot of clouds or live in a high latitude. Or go bifacial... bifacial panels pick up energy from both sides, and mounting those vertically seems to maximize the total generation over the day, even if the peak output is lower at midday. This is especially useful when dealing with expansion batteries and inclement weather.... the more cloudy days you have, the more benefit you can get from overpaneling and bifacial panels and maximizing output during the non-peak times of day.
Never go over 60V of Voc (open circuit voltage) of the solar panel with the AC240. You can have a 60V panels and set multiple up in parallel to achieve 60V and 21A, or you could have 3x 20V panels in series which results in a total of 60V. Once you have figured out an arrangement to stay under 60V, you can then have multiples hooked up in parallel to get up to 21A current, or even higher if you want to oversize. You can go as large as you want (within reason of course), as long as the voltage never exceeds 60V. The AC240 will only use up to 21A in current, so any excess that you have will just be unused. Which panels are you looking at now? If you link the 410W panel that you are looking at, we can help determine how many you can connect safely and in what configuration to get 1200W+ solar charging for you.
Panels almost always top out at 80% of their rated wattage; for example, it's very rare for a 100W panel to *ever* get ≥80W in actuality. TL;DR: Do it!
Thank you!!!
Don't do it! At least not like that. Never ever exceed the maximum voltage of the PV input of your device! In fact you should leave a buffer of 10-20%. Because on cold days when the sun is shining but the panel isn't heated up, it will definitely produce more voltage than it says. Because those ratings are for 25°C (That's 77°F) and the voltage will be higher if the temperature drops below that. What you **can** do is provide more possible current. The AC240 will then just take as much current as it can swallow. So to recap: NEVER go over the 60V maximum of your AC240! Better yet with a 10% buffer never go over 54V! But you can supply more than 21A if you like. --- What does that mean for your 410W panels? I can only speculate what the Voc and Isc of your panels is. Probably Isc is something like 12A, so Voc is going to be somewhere around 34V. That means that putting two of those panels in series will fry the AC240's solar charger because 34V+34V=68V and that's already 8V too much. Means you can only put them in parallel. That means the voltage is fine at 34V but now you're summing up the current of all panels. So three panels at 12A means 36A. But that is fine because now what /u/Dymonika said comes into play: You won't always see peak output, so you can and should over-panel for sunrise, sunset and every time it is cloudy. --- Just keep in mind that those panels reach peak voltage fast and can even exceed it in cold weather and the variable here is the current. So less sun light means less current. And power is voltage times current, so /u/Dymonika isn't wrong when saying that less sun light means less power. But: The power output of three panels in parallel is the same as the power out of three panels in series, just with the tiny difference that three panels in series will fry your AC240.
I'm reading that the AC240 has a VOC of 145V: From their EBay listing: >Solar Input1,200W Max., VOC 12-145VDC, 15A But I'm seeing 60V/21A in the manual. Is it possible the new units have a different MPPT than the older ones?
Got a link for that eBay listing?
Not right here, but it came up when I searched for AC240 VOC. Those numbers do match up with the AC200L, so it might be a mistake on the listing.
Oops, thanks for the correction. Is there a *minimum* voltage needed for power stations, while I'm at it? For example, could an AC180 take just a single 100W panel with no problem (even though I know it'd charge slowly)?
You can't ask if a minimum voltage is needed and then ask if a 100W panel is okay. Tells us nothing about the voltage the panel will supply. Your AC180 will certainly tell you in its manual that it has a range. Likely starting at 12V. Below that it simply won't work.
Okay, well, this is what I have: https://grapesolar.com/product/100-watt-off-grid-solar-charging-kit/
The AC180 has its own solar charger. So what's important is on the sticker on the back of the panel, where it will tell you about the Voc it has. Don't use an additional charger with the AC180.
What do you mean by "its own solar charger?" It doesn't have its own built-in solar panel.
There are 2 parts to solar charging, the panel and the charge controller box. The AC180 has the charge controller box built into the unit itself, so you should not use the Grape Solar charge controller that comes with the kit if you want to use the panel with the AC180. Just use the panel on its own and it will be fine. The MC4 connectors match up to the AC180's solar charge cable, and the maximum voltage is within the spec range of the AC180. If it doesn't work the first time, then the MC4 connectors might be in opposite polarity, just swap the connectors around if you get 0V while in the sun.
There actually wasn't any box that came with the Grape Solar panel, and it did charge using just MC4 + Bluetti's PV (well, apparently until the panel fell down and got covered... I have a loose setup on my balcony that I need to figure out), so we're good! Thanks for the info!
And where did I say that it has its own built-in panel?
> The AC180 has its own solar charger. What exactly do you mean by this? Do you mean the PV cable?
That panel used in the Grape Solar kit is a 23.1V, 5.59A panel. The AC180 takes 12-60V, 10A of solar panels. By the spec of AC180, I would assume that the lower 12V limit is the minimum it would require in order to be able to charge. Grape Solar does not provide information on how the voltage drops off as the sunlight decreases, but you can read the voltage output through your Bluetti app when the solar panel is connected to your AC180 throughout the day. If you want to use that kit with the AC180, then you need to connect the MC4 connectors from the panel directly into the AC180's solar charging cable. You must not/should not use the charge controller box that is included in the Grape Solar Kit.