Miss matched solar panel's

[molly 2]

Solar charging a bluetti 180 p I have 2 Solar panels
1 a ,200 W folding panel made for power stations puts in 150 W

2 b ,100 W standard glass ppanel puts in 50 W

3 C Connect both Panels in parallel output puts in 158 W

I know miss matched panels are bad idea but an increase 8 W shows how bad it can be . readings taken from Bluetti .mppt controler
Output 200 21.4 vmp18.2
Output 100 21.6 vmp17.5

 

[wildebus]

Solar charging a bluetti 180 p I have 2 Solar panels
1 a ,200 W folding panel made for power stations puts in 150 W

2 b ,100 W standard glass ppanel puts in 50 W

3 C Connect both Panels in parallel output puts in 158 W

I know miss matched panels are bad idea but an increase 8 W shows how bad it can be . readings taken from Bluetti ..

you can actually end up by a REDUCTION in power if you really go to town with badly mismatching panels.

But .... there is no reason why you cannot mix and match different PV panels on the same controller IF you are careful in your selection.
Take this installation here on this Malibu I did a year ago ....

There are five different sized panels on this roof out of the 6 fitted and they all go to the same single controller and work together as they need to.

Just mentioning this as a a statement saying "miss matched panels are bad idea" is a bit too strong and unclear.

 

[Fisherman]

I have four panels on my roof two

120w and two 45w.
Although their max rated output is only 330w I have achieved up to 360w whilst down south and in the north of Scotland this year I have managed 295w.
And the two larger panels are mono crystalline, whilst the two smaller ones are poly crystalline.

 

[molly 2]

you can actually end up by a REDUCTION in power if you really go to town with badly mismatching panels.

But .... there is no reason why you cannot mix and match different PV panels on the same controller IF you are careful in your selection.
Take this installation here on this Malibu I did a year ago ....

There are five different sized panels on this roof out of the 6 fitted and they all go to the same single controller and work together as they need to.

Just mentioning this as a a statement saying "miss matched panels are bad idea" is a bit too strong and unclear.

You are correct I should chosen different wording

 

[yeoblade]

I mis matched mine on purpose, to reduce the Vmax input to MPPT to 24vdc. so can be useful sometimes!

 

[wildebus]

I mis matched mine on purpose, to reduce the Vmax input to MPPT to 24vdc. so can be useful sometimes!

would you have a CTEK D250 Charger by any chance?

 

[yeoblade]

Nope, fitted a Renogy 30DC/DC/MPT and it only takes 24v. Was baffled for a while why it kept stopping as the solar got stronger, then realised the panel was giving 28v. Fitted another,100w, panel 24vmax in series as the simplest solution for my setup. I see they have ungraded the product it to take 50v now

 

[wildebus]

Nope, fitted a Renogy 30DC/DC/MPT and it only takes 24v. Was baffled for a while why it kept stopping as the solar got stronger, then realised the panel was giving 28v. Fitted another,100w, panel 24vmax in series as the simplest solution for my setup. I see they have ungraded the product it to take 50v now

Lucky only effect was stopping! some of these Combi Chargers will blow up if the Solar voltage limit is exceeded

 

[yeoblade]

Lucky only effect was stopping! some of these Combi Chargers will blow up if the Solar voltage limit is exceeded

Luckily I didn't have to test out their warranty procedure then!

 

[merl]

Solar charging a bluetti 180 p I have 2 Solar panels
1 a ,200 W folding panel made for power stations puts in 150 W

2 b ,100 W standard glass ppanel puts in 50 W

3 C Connect both Panels in parallel output puts in 158 W

I know miss matched panels are bad idea but an increase 8 W shows how bad it can be . readings taken from Bluetti .mppt controler
Output 200 21.4 vmp18.2
Output 100 21.6 vmp17.5

I know things need to need to be perfect to get 100% efficiency and there's usually some loss when paralleling but additional 5w doesn't seem right??? This sort of testing needs to be carried out on a very clear day because changing conditions can lead to inconsistent measurements and inaccurate conclusions.
Assuming parallel connection then for maximum efficiency the voltages of the panels should be as close as possible at their maximum power point and not open circuit voltage as often quoted.

 

[molly 2]

I have decided the miss match could be the problem . the 200w power station panel is semi flexible etfe light weight panel the 100w is glass panel

 

[wildebus]

I have decided the miss match could be the problem . the 200w power station panel is semi flexible etfe light weight panel the 100w is glass panel

have you got the specifications of the two panels? Need the voltages and current info to work out what you can expect as a maximum and the best way to connect the pair.
There is some simple maths that can be used to work this out.
One being EFTE and one being glass is not the critical factor.

 

[molly 2]

have you got the specifications of the two panels? Need the voltages and current info to work out what you can expect as a maximum and the best way to connect the pair.
There is some simple maths that can be used to work this out.
One being EFTE and one being glass is not the critical factor.

Details on early post 4 up from here

 

[wildebus]

Details on early post 4 up from here

Ah. Added to edited post later on. Didn't see you added info.

Those specs suggest the panels are fairly well matched on Voltage. What is the CURRENT info on each of the panel specs? How are you connecting the panels?

 

[molly 2]

Took some reading today from bluetti app

100 w panel 65 w , 14.9 v 4,3 amps
200 w panel 146 w 14.4 v 10.1 amps
Both Panels in parallel 153 w 19.3 v 7.9 amps

 

[merl]

That looks like an issue with the solar controller either not being MPPT type, 14.4v/14.9v looks more like PWM type. Alternatively the controller may not being able to handle the potential increase in current that MPPT operation would bring and so staying in PWM mode, maybe your battery be close to fully charged?
If not I suspect you'd see a significant gain by using a decent 20A MPPT controller.

 

[molly 2]

That looks like an issue with the solar controller either not being MPPT type, 14.4v/14.9v looks more like PWM type. Alternatively the controller may not being able to handle the potential increase in current that MPPT operation would bring and so staying in PWM mode, maybe your battery be close to fully charged?
If not I suspect you'd see a significant gain by using a decent 20A MPPT controller.

It is a power station built in 500 w mppt Controller.

 

[merl]

It is a power station built in 500 w mppt Controller.

Yeh, I get that BUT the figures you posted don't concur.
It could simply be that the battery is nearly full but could also be inaccurate reporting by the charge controller or something more sinister like the controller not actually being as advertised. IF you're bothered (I would be personally) then first I'd ensure the battery isn't anywhere close to full and repeat the process and take actual voltage measurements at the panel input terminals. Ideally you'd check the current with a DC clamp meter too. (Did I ever mention that everyone should own one?)

 

[yeoblade]

Took some reading today from bluetti app

100 w panel 65 w , 14.9 v 4,3 amps
200 w panel 146 w 14.4 v 10.1 amps
Both Panels in parallel 153 w 19.3 v 7.9 amps

I have a similar situation, using different make panels in parallel the actually output doesn't agree with the theoretical output at all.

 

[molly 2]

Yeh, I get that BUT the figures you posted don't concur.
It could simply be that the battery is nearly full but could also be inaccurate reporting by the charge controller or something more sinister like the controller not actually being as advertised. IF you're bothered (I would be personally) then first I'd ensure the battery isn't anywhere close to full and repeat the process and take actual voltage measurements at the panel input terminals. Ideally you'd check the current with a DC clamp meter too. (Did I ever mention that everyone should own one?)

The input puts in max watts irrelevant of state of charge, the bms shuts down the charge when battery reaches 100 p full .

Is that how standard lithium batterys charge ?