Will this PV input voltage ok for Infini 3kw plus?


#1

Salam, hope everyone is doing ok. I am planning to upgrade my solar system in coming months so I need some suggestions from you guys. My current system is:
6*295w solarworld panels, connected as 2 parallel arrays of 3 panels in series.
3kva axpert inverter with 48v battery bank of 4 AGS 200 Amp Hour batteries.

So my future plan is to buy infini 3kw plus model and add 4 or 6 more panels of 350watts Solarworld as I cannot find the 295watt panels now in the market. The short circuit current of these new panels (350watts) is the same as the old 295watt panels I have, so I believe I can wire them both in series.

So here is my plan:
Buying 4 or 6 of the 350watt panels and make two arrays in parallel. Each array will be 3295watts panels plus 2 or 3 350watt panels in series.

The spec sheets of both type of panels is as following. Kindly advise me should I go for 4 of the new 350watt panels or 6 of them.

Rated max power 295w 350w
Open Circuit Voltage (VOC) 40.0V 47.3V
Rated Voltage(Vmpp) 31.5V 37.8V
Short Circuit Current (Isc) 10.10Amp 9.82Amp
Rated Current (Impp) 9.45Amp 9.29Amp

Any response in this matter will be highly appreciated.


#2

preferably keep same panels on one mppt.
i personally will not combine panels having 6 volts difference per panel(Vmpp 295W vs 350W). over a string of 6 panels that will be 36 volts difference.

you can look into infni V series(green body). 5KVA version has 2 separate mppts(low volt dc input). can do hybrid(sync with utility and use solar first) and feed-in also.
though not as efficient as infini original.


#3

Thank you very much for the response. That’s what I was thinking now. If I go for infini 5kw v series, I can have more capacity to run the loads compared to infini 3kw plus (3kw vs 5kw) and not put pressure on the charge controller as well, as if I have two parallel arrays of the solarworld panels, the input current will exceed 18amps during peak sun hours. I am thinking about moving the panels I have to one mppt input of infini v series and since the input voltage is onlt 145 VDC, I dont think I can use 3 panels of 350watts in series as the input voltage might be too much for the second charge controller.

So keeping this in mind, I think I can use panels of lower wattage than 350w (probably 250w to 270w) of any other good brand. This way I will be able to save money on panels and can use it for batteries in future. Do you have experience with Jinko solar panels? Or maybe any other good brand panels which you could recommend to me?


#4

How much is the difference in efficiency of infinisolar plus and infinisolar v series inverters? Plz elaborate if I have 3400watts of panels, what will be the peak output of both.


#5

With mismatched panels, the best way to go is to get Infini V 5KW. It has dual MPPT and you can wire two separate strings.

With 3KW infini plus you can have the following configuration, as long as the voltages match on both strings or there is very little voltage difference between the two strings.

String 1: 6 x 295W panels wired in series = 1770W VOC 283.8V
String 2: 6 x 350W panels wired in series = 2100W VOC 283.8V (since you are saying VOC is same as 295W panel). Parallel both strings together. Now your short circuit current will be 9.82amp of string 1 + short circuit current of string 2, which is probably going to exceed the maximum current rating of 3KW infini plus which is 18amp.

But you need to keep in mind that solar panels generate voltage. Under no load, current is zero even though voltage might be 240V. Current is pulled by the inverter using the load that is connected. You cannot exceed the maximum current of the charge controller, since it will limit it to the maximum 18amp.

You can stay within the lower limit, by limiting your load. So calculate how much current inverter is going to pull at maximum load. On a sunny day when voltage is high lets say for eg 240V if you have a load of 3000W and all the load is powered by PV then the current you are pulling is 3000/240= 12.5Amp which is much below the MPPT limit.

The problem is when voltage is low. Lets say your load is 3000W but suddenly there is cloud cover and voltage from panels drops from 240V to 140V while load remains the same. Now you are pulling 3000/140 = 21.4Amps which exceeds the MPPT limit. What will happen? As per design, Infini should offload some load to grid and never exceed 18Amp. But in the unlikely event that it can’t react fast enough then most likely MPPT will trip, Inverter will give an error code 11 (Over current on PV input is detected). But it is unlikely it will break the inverter. To be on the safe side you can limit the maximum load on the inverter. You can also put a 15Amp fuse on the PV input to break the circuit before it reaches the 18amp limit.


#6

I think you misread my post, rated current of both kind of panels is almost the same, 9.29 and 9.45, VOC is very different (40V for 295w and 47.3V for 350w). I am more inclined to go for infini v 5kw now. I think very large panels like 300watt and plus are not very compatible with infini 3kw plus model as two strings will generate more than 18 amps of current.


#7

I have 2 strings wired in parallel each string has 6 panels. Short circuit current of each string is 9.05A. So total short circuit current is 18.1A, which is slightly more than Infini 3KW Plus can handle. But my load is less about 2000W max. Current is determined by your load, you cannot pull more current than what the load wants.


#8

You are very right when you say that only current needed for the load is used by the inverter. Maybe you know this or someone else can give input on this that what is the maximum load that infini 3kw plus can take if it is set on SUB (Solar Utility Battery) mode.


#9

Are you asking about surge current or continuous load? For continuous load, of course theoretical maximum is 3000W. But everyone I talk to has a different opinion about how much continuous load to put on the inverter. Personally, I wouldn’t be comfortable with more than 75%.

If you are talking about surge current, then I have seen my inverter take a surges up to 5200W mainly due to 2 non-inverter fridge that are running at the same time along with a 1 ton AC. The surge happens when the compressors kick in at the same time. On another forum someone who has an Infini 3KW + claimed that he has seen his inverter handling surges exceeding 7000W.


#10

I was talking about continuous load. I am not really worried about surge current as I think my home will have a max surge of 4000W if AC and water pump are run together which is highly unlikely. I am living away from home and not everyone is very cautious about using bigger loads in the form of one at a time. So having more capacity to run the loads will benefit me as it will give me peace of mind. I think the home has around 3200W continuous load for few hours in the day time during summer. Like you said running an inverter under 75% of maximum capacity will ensure longer life of it.

That’s why I am thinking more of infini 5w. The plus version is much better but comes at a hefty price of 195K and I think if voltage of array is below 250VDC, it will not be very efficient. The V series version makes more sense to me.


#11

V series 5KW is definitely better for your scenario, since you also have the issue of mismatched panels. The only problem with V series is the low MPPT range 60 VDC ~ 115 VDC. That means you will have two solar arrays. Array 1 will have 3 strings of 2 solar world panels connected in series to get a DC open circuit voltage of around 94V and then combine the three strings in parallel for a short circuit current of 29.46 amps. Do get thicker PV wires though, 10mm2 should be more than enough.

Your second array will also have a similar configuration depending on its VOC and ISC. Also keep in mind that with three or more strings, you need to also put a fuse in each individual string.


#12

I can actually use 2 strings of 3 panels in series like I have set up for my Axpert 3KVA for more than an year now. One string has an open circuit voltage of 120VDC and operating voltage of 94.5VDC. Having 3 strings will not be wise as there will be too many wires for basically nothing. The only issue I will have , is if I go for infini V series I will be better off buying 6 more panels of 250W to 290W of any good company as 350W panels of Solarworld will be too large to wire 3 in series (VOC nearly 143 and can go higher in winter). These new panels can be connected to the second charge controller input of infini.

Anyway, I will see how it goes and will keep you posted here.


#13

60-Cell panel, 3 in series will be good for infini-V in terms of voltage. Voc <145 and mppt 60~115.
I guess, you can connect up to 3kW of panels per mppt of infini-V.
No experience of Jinko. But Jinko, JA, Solar World, Q-cell Hanwa are all respected brands, I guess any of them will be equally good.

As per spec. sheets, DC to AC efficiency is 96% of 3kw+ and 90% for infini-V (in grid-tie mode).
under battery mode infini-V is 2% better.
But these are mostly lab values and not close to real world results.

For battery based systems, in real world (high temp.) 2/3rd of installed panels output is to be expected.

Download the manual of infiniV, it has more specs on last page.

“On another forum someone who has an Infini 3KW + claimed that he has seen his inverter handling surges exceeding 7000W” <-- surely with Utility available(hybrid/sync mode), infi 3kw+ DC-bus is not rated for this, if you surge it with 7kW under battery mode, it will definitely be not happy.

with 2 mppts, if you wish, face one mppt’s panels toward west and one mppt’s south. west one will give better output in summer afternoons. (mid june-july sun is almost west in afternoon)


#14

I have the infini V and the 3kw plus manuals on the pc, will have a detailed look at them again. My current array (shown in the picture below) is facing south west and has been giving great output during this summer. It was under powered though, especially after we got 1.5 ton AC few days back. I am planning to keep the angle and tilt of solar array same going forward.

I am using 4 AGS batteries of 200 amp hour capacity. They are okay if used for a few hours back up but not full night. I plan to get 8 tubular batteries in future when the current batteries are dead and have them connected in two strings. If I happen to get a net metering license before that, my plans might change from 8 batteries to 4 batteries similar to current set up.


#15

2/3 of the installed panels is actually very good. I am planning to have new panels of 1600-1800 watts so total installed capacity will be 3400-3600 watts. 2/3 of that will be nearly 2.5KW, not bad. That will definitely give me loads of peace of mind.


#16

batteries are expensive, they waste energy(generally around 30%), they get consumed(every time you charge and discharge them). 5, 10 or 15 years life is when you keep them on float charge and use them once in a while. a reasonable size bank for the essential loads is preferable.

running an air conditioner on batteries(overnight) require a lot of battery storage.
net-metering should be first priority. heard that now they are net-metering on 3-phase only, not sure though.

i will suggest running air conditioner at full throttle during sunny-hours with solar energy. at night the room stays quite comfortable even if air conditioner is turned off.

and the 2/3rd output will be for peak hours, not whole day.


#17

I have a very good idea about expense and size of the needed battery bank as I have been a solar system user for over 4 years now. That’s why net metering is a priority for me but you know there is so many red tapes in our government systems so getting a net metering license isn’t a smooth process. I have confirmed from lots of folks in Lahore and from LESCO website as well that you need to have a three phase connection for net metering and that’s a must. The inverter can be single phase if it is not more than 5KW. For a solar system of more than 5KW installation, the inverter also needs to be three phase.

My current system has a rated capacity of 1770W and it gives about 1300W for around 4.5 hours during the peak sun hours and it has been sufficing almost 60% electricity need of the house. 2/3 of the upgraded system which I assume is around 2.5KW during the peak sun hours, is what I am looking for. Currently if we start the AC even during peak sun hours, we are almost 800W in negative. Once the room starts to cool down, the consumption of the AC drops. If I can have additional capacity for PV generation, I can cover this gap of 800W. I plan to use the inverter in SUB mode so that if grid is available batteries are not used as they are definitely more expensive than grid. A hybrid inverter isnt very useful anyway if I am going to use batteries before grid.


#18

I have been logging my system’s data online using pvoutput.org and emoncms for a while now. Here is historical data of my system using the former:

https://pvoutput.org/intraday.jsp?id=61384&sid=54649

And here is live situation:

https://www.emoncms.org/dashboard/view?id=50400