Some panels have varying temperature coefficients which means some panels may perform slightly better or slightly worse as the temperature climbs or dips below or above the standard test condition of 25C/77F.
It’s important to note that while the panels can operate in extreme climates, your true bottleneck is your solar generator. Lifepo4 batteries simply won’t allow you to charge if they reach an internal temperature below 32F or above 104F. This means you pretty much are only running the panels when the conditions are right anyways.
The standard test condition of the panel is specifically rated at 77F/25C and 1000 W/m² of solar “power”. However in the peak of summer, you can exceed 1000 W/m² during solar noon, which means a “rated” 350 panel may actually produce around 400 watts of solar, an increase of 12.5%.
The maximum theoretical power a panel can be produced can be calculated by finding its Area×Irradiance×Cell Efficiency. Keep in mind it won’t actually convert 100% into “usable” energy to the generator itself. So take my Bluetti PV350 panel. It has an area of 2.172m². The cell efficiency is “up to” 23.4%. So I take 2.172 X 1000 X 0.234 and I get 508 watts. You won’t get 100%. Say my panel loses 5% from the hot sun. It loses another 15% from internal resistance/heat dissipation and another 3% from the wiring/, this would be a total loss of 23%. This means I’m getting around 77%. What’s 77% of 508 watts? 391 watts, which explains exactly why I’m getting 390 ish watts during the peak summer months at solar noon.
The reason why you want to know the OCV of your panel and the effects that temperature plays on voltage when its colder/warmer is specifically if want to combine solar panels in series. The solar panels will operate at slightly less power while under a load (i.e. a solar panel connected to it), but this does not matter. What matters is the initial voltage surge when you first connect it.
For smaller units like the Bluetti EB3A/EB70S with a low VDC (12-28V), I find that most optimal setup is to run two 200 watt panels in parallel. The reason why is since you are limited to 28V and 8.5A, you want to run in parallel to combine the amperage. If I’m not mistaken the EB3A won’t even start charging until it has reached atleast 18W of input, so if one panel is running at only 15W, you will see zero/“Low voltage” error. During overcast days the amperage is very low, so combining them is the most beneficial. Here’s a video I made showcasing this benefit on my EB70S: Running Two Solar Panels in Parallel on EB70S
Assuming the operating voltage was 18.5V the amperage would have been around 1.08A, meaning that when I ran in parallel i am now getting 18.5V X 2.16A or 40W as indicated on the generator. The maximum watts I have ever seen on my EB70S was around 165 watts. In the video above, earlier in the day when the clouds were not as thick I was getting around 65 watts for each panel, which means since I was able to take advantage of the combined low ampearge, I was able to double my capacity to 130 watts, which is 78% of its max solar charging capacity on a CLOUDY day. To give you an example, say you have a solar panel flat mounted on the roof of your vehicle and its sunny out. No need to whip out an additional panel because your EB70S will be getting enough power likely. However, if its day where its overcast, or it may be a mix of sun and clouds, you could whip out a portable solar panel and tilt it toward the Sun. The amperage of the two panels will combine to increase your input, but in the event the sun ever does peak out, your tilted panel will take full advantage and you will max out the input on your EB70S, creating an optimal configuration. The MPPT controller will simply reject any amperage above 8.5A which is the most the EB70S will allow in. So if its sunny out and each panel is producing 6A, it won’t double to 12, it will see 8.5A and reject the remaining 3.5.
The way I look at it is the Elite 200 is basically 2 AC 180s together. 12-60VOC and 10 amps plus 12-60VOC and 10 amps, for a total of 12-60VOC + 20 amps. Given you can realistically only series 2 panels together, I’m thinking 2 in series/2 in parallel.
Pretend a single 200 watt panel is 21.6V/9.1A.
Panel 1a 21.6/9.1A
Panel 1b 21.6/9.1A
Series 1 = 43.2/9.1A
Panel 2a 21.6/9.1A
Panel 2b 21.6/9.1A
Series 2 = 43.2/9.1A
Create parallel connection between Series 1 and Series 2 = 43.2V/18.2A (in parallel the amperage doubles but volts stay the same)
43.2X18.2 = 786 watts out of 800 watts worth of panels
Sounds abour right. Connecting two pairs in series would mean that each pair have 45V 11.11A. If you now connect both pairs in parallel, the voltage stay at 45V and the current will add up from 11.11A to 22.22A.
As you say, the MPPT will cut all above 20A.
greetings
Erik
PS: When the unit is under a certain voltage, it cant use the full 20A. At 45V, you should be easily over this
Hi, I have a AC200P and would like to charge it using a Renogy 200w flexible solar panel. When I plug the solar panel in the Bluetti reads 25 volts input but no watts, so therefore not charging. It would appear they are not compatible, is there anything I can do? or can someone suggest a flexible solar panel that is compatible?
@Fitzy You are outside the VOC range. In other words your panel voltage is too LOW. The AC200P has a VOC of 35-150V which means it needs a minimum of 35V to start charging the generator. Any less then that and you won’t start charging the generator.
I would like to connect my Bluetti AC180 to this solar panel
Is this possible?
Has anyone already gained experience with this solar panel?
I would really appreciate your opinion.
Thanks in advance!
JA Solar n-Type Bifacial double glass All Black 445Wp Solar Panel
The JAM54D41-430N-LB-BK has a power of 435 watt peak and is equipped with 108-BF-NT cells. Thanks to the innovative half-cut cell technology, this panel performs better due to a lower temperature coefficient.
This bi-facial solar panel with black frame has dimensions of 1762 × 1134 × 30 mm. The manufacturer’s warranty is 25 years on the product and the capital guarantee guarantees 87.4% of the original capital after 30 years.
Dimensions 445W Solar Panel (H x W x D) in mm: 1762 x 1134 x 30 mm.
Weight in kg: 22.0 kg.
Cell type: PERC Monocrystalline Full Black
Max. power (Pmax): 445W
Max. voltage: 32.65 V
Max. current (Imax): 13.63 A
Open voltage: 39.10 V
Short-circuit current: 14.40 A
Possible, yes, but would be heavily under utilized due to AC180’s 10A limit on MPPT controller. In other words, since the max the AC180 can accept in current (amps) is 10A, it will reject anything past that meaning, you will max out at 32.65X10 or just 326.5 watts. Further more, if the voltage dips below 32V, it caps the amps at just 8.5, meaning your likely real world output is more so around 275 watts. Realistically the best you will be able to do in the real world for the AC180 is around 400 watts, due to open circuit voltage limit of combining two panels in series, along with the 60V VOC limit and 10A bottleneck on the AC180. Most panels above 300W will simply have an optimal current well above 10A to make up the wattage of the panel. In other words, you will likely see a a 400W panel that is 32V + 12.5A, not 40V and 10A. Every value after 10 is just wasted power. The Renogy 250 watt for example, two of them makes 500 watts, but since they operate at 19.52V and 12.81A, this means the most you will get is 19.52X2 (39.04V) plus 10 amps or 390 watts, around 400 watts as i stated before.
welcome to the bluetti community forum and thanks for your question!
The AC180 have a PV input of max. 60V. Your Panel have a max voltage of 39.10V and is within the range of 60V.
You can use it
The only thing you need to be aware of is, that AC180 have a 10A limit. Means you cant use more than 10A for charging. Instead of 32.65V and 13.63A (which will be 445W) you are only able to charge at 32.65V and 10A which will be 326W.
So you dont damage anything, but also cant use the full power.
For reference the highest I have ever gotten my AC180 from purely solar charging is around 450 watts.
I ran two PV350s in parallel which gave me around 38V and 10A during peak solar (380 watts)
The remaining 70 watts I got by was tethering an AC cable to an EB3A and charging the AC180 (in silent mode) from AC input.
So 450 watts… 380 (PV) and 70 (AC).
I then charged the EB3A using a PV200. So the only source of input power was originating from solar. Highly inefficient to charge it this way, but just for demonstration purposes. Assuming the EB3A was 50% efficient at discharging AC at 70 watts means I’m actually consuming 1.5X that OR 105 watts, meaning as long as my PV200 is giving me 105 watts of solar I’m maintaining a net charge. Any less then that, and the EB3A is LOSING power, despite it containing to charge the AC180 over the AC input port.
There is a benefit from “over clocking” solar input many do not realise. NOTE - I refer to Amps exceeding input limit NOT Volts.
The MPPT controller will absorb or block those extra Amps when the panel/s are in full sun. However, the benefit will occur earlier and later in the day, when solar output is not as high.
Simple analogy - If output = 12A and is limited to 10A charge, when output drops to 10A you still get max input. If the panel output is at 10A max, it has nothing to spare when output drops below maximum.
So, you get more power for longer. I do not know the theoretical maximum of the Bluetti MPPT, but from my experience, exceeding output by 10-20% should cause no harm. Which in real terms @ 10A limit is only 1-2A.
I won’t mention brand etc, but my RV power supply MPPT has a 50V Voc at 20A charge. It has a nominal 600W limit, but the manufacturer states it will Accept 800W without damage.
The problem is that it’s all new to me, and therefore difficult in terms of making a choice. I’ve watched so many videos about the Bluetti AC180 and solar panels that I’m completely confused and don’t know what exactly I should buy. I can’t see the forest for the trees anymore. I was first thinking of a portable solar panel, but on second thought I think they are quite expensive and more intended for an off-grid holiday, also not very convenient to use. Such a panel is something for later. For me, the Bluetti AC180 is therefore more intended for home in the backyard and in the event of a power outage of the public network.
I think a fixed connection with one or 2 solar panels is therefore the most suitable. I would therefore prefer to mount 1 or 2 panels on my garden shed. The roof is made of bitumen shingles measuring 280 cm x 190 cm. I prefer the Input of the cable on the back-side. See attached photo
I live in the Netherlands, where not just everything is available. I can only order something through Amaz**.nl and Bol.***
Maybe someone can help me further with the purchase of fixed solar panels for the Bluetti AC180 and possibly. Installation advice for this:
Should I buy 1 or 2 solar panels? E.g. 1x 400 Watt or 2x 200 Watt?
Which brands of solar panels and with which technical specifications are most suitable for this?
Because of the current limited budget, am I looking for the best price-quality ratio?
Very well said @Mandp . A pair of PV350 panels pairs nicely with my AC180. I mostly just lay them flat on the ground and use a parallel DC7909 Y splitter cable to connect the two panels together (this way I’m not having to muck with the MC4 connectors). Setting up and tilting panels is a pain, so I’d rather just buy two and lay them flat on the ground. On a sunny day I get the maximum 400 watts or so no problem, but I reek the benefits of doubling the amperage draw on cloudy days, since flat panels capture light better when its diffused (i.e. its overcast). On a horribly overcast day I can still pull in around 75-90 watts on 1 panel, which means in parallel I can get 150-175 watts, allowing me to completely recharge (just about) the AC180 in just 1 day. I really only ever struggle if it is about to rain, because the panels can’t be used in the rain, but its a moot point because you will be lucky to get 15W from the panel in the rain anyways.
@Bluemoon For a pitched roof you are likely going to want to go with a monocrystalline panel to maximize space and long term durability, since it will be out in the elements all the time. A pitched roof system works best if you are oriented in the best direction. In the southern hemisphere that would be north-facing. If its south-facing the Sun is going to go behind that tree and ruin your day. Along with that you will need some type of railed system to prevent water intrusion so the water can drain out properly and not ruin your roof. You also want ventilation for your panels as well.
The problem with the AC180 is you are capped at 1kWh of power and after the battery is topped off, any more energy from the Sun is wasted potential. The AC180 is simply not the correct application for a roof mounted solar setup. Generally you want to invest into more house batteries so you can take advantage of the Sun providing you more storage potential throughout the week. So the Bluetti ecosystem that supports the expansion batteries. Once your AC180 gets 1kWh full of power, that’s it. No more. But if you could have the Sun soaking up power from the panel ALL DAY for 5 days, topping off your expansion batteries, you now have say 10kWh of reserve power, vs just a measly 1kW.
If 400 watts will do you just fine and the AC180 is sufficient, I would recommend 2 200 watt in series because if one panel breaks the replacement cost is less. Say 1 400 watt panel costs you $800, but you can get a 200 watt panel for $400. You are only out $400 instead of $800. Just be advised the cost of mounting on your roof will NOT be cost effective to implement this type of system. Generally you are utilizing a roof mounted system to capture MORE solar potential through a larger battery bank, and not just to fill up a small 1Kwh AC180.
Here’s two PV350s in parallel on an overcast day and my output. You generally get around 25% of your power on an overcast day. 350+350=700, so since I’m getting 175 watts, 175/700 is 25%.
Here are some real world results as I am currently out bush, this is my set up. The 2 panels in the foreground are each 150W solar matts and there is a 160W panel on the roof of the caravan. There are 2 x 100Ah LFP house batteries in parallel for a 200Ah total.
It is around 11am, clear skies, mid Autumn and battery temp is 20 deg C.
This first meter reading shows a solar input of 17A @ 13.9V = 236W. The actual charge is 15.5A, which means the caravan is using 1.5A of the 17A input.
The second readout shows what happens when I plug the AC180 into the caravan system for a slow charge. It’s still showing a 17A solar input, but only 6.4A going to the caravan house batteries.
This last pic shows what is going into the AC180 = 97W and roughly 1.5 hours to charge. The 11% use was last nights frozen meal cooked in the caravan microwave powered by the AC180.
This shows that even with good conditions I am only getting 236W of solar from a total parallel string of 460W. As the on roof panel is horizontal I would not expect more than 110W from it especially at this time of year. I’m happy with 236W from an expected 400W max.
I’ve been where I am for a couple of weeks, I expect to see the AC180 fully recharged and my RV house batteries at between 95-100% by the time solar stops producing. This shows that if you recharge a power bank just from a 12V source, every day you don’t need fast charging. It also highlights a reserve use of 5-6 days without charging for my type of use.
Forgot to mention - I have had this setup operating at the height of Summer, where I see a solar input current of 25-26A at the same voltage = 361W of the total 410W expectation = 88%.
The above Autumn result works out to approx 58%.
These results show what angled orientation improves and even on a sunny day in Autumn how much loss can occur.
Can I improve what I have? Absolutely - I could double the solar array size, but the questions I need to answer are; where do I put the additional equipment and can I carry the extra weight? My answer is No. So, when I get several days of bad weather, I fire up the small 800W petrol genny, which is just large enough to charge/top up my RV house batteries if needed. It weighs 10kg, a 200W panel weighs more and is still subject to weather conditions.
As mentioned, I’ve been out for 2 weeks, the genny has had 1.5 hours on one day of use.
It’s now 3pm - AC180 is fully charged, Caravan house batteries are at 96%. The display for the caravan still shows 8A of solar input and 4.5A still charging the batteries.
Tree shade will unfortunately stop solar in around 1/2 an hour.
The caravan fridge is a 110lt 12V compressor type, plus I’m running the laptop and 2 mobile phones.
Nice. I do the same thing except with an ALP Propane Generator that outputs 800W which I can siphon from one the two 10lbs propane tanks on my Moonlander. My biggest power source is my 12V fridge. I have an EB70S and AC180 as house batteries dedicated to just the fridge and reserve power. Ultimately, you have to orient yourself to favor sunny conditions because you won’t maintain a net charge for very long, even with a large battery bank. And even then, sunny locations can let you down, so backup source is crucial. DC-to-DC charging from your starter battery/alternator with Bluetti Charger 1, an LP/gas generator, and solar. I have been able to depend on solar maybe 75% of the time, with the remaining 25% being me needing to top off from the truck on a small road trip, or use of the ALP generator.
