Connecting different wattage solar panels in parallel

[Shoney]

I have a Renogy 100w 12v suitcase panel that when I atrach it to my Anker 757 power station I am getting around 85w.
When I attach a 200w 12v Renogy eclipse solar panel I get about 170w.
When i connect them in parallel I am getting about 180 - 190w when I would expect to get 85w + 170w = 255w.
Dont know why yhis isn't so?
Any ideas.

 

[JoeHam]

You don’t give panel specs so it’s hard to say.

Read this, it should help :

Mixing solar panels – Dos and Don’ts • SOLAR POWER SECRETS

Mixing Solar Panels: Discover Now Dos and Dont's of Mixing the Same Types or Different Types of Solar Panels. Act Now to Save Your Money!

solarpanelsvenue.com

 

[Shoney]

See specs below if that helps

 

[DThames]

The watts that you "get" are the power that your load (doing work or charging battery) is. Do you have a load of more than the 255w that you have observed? Those panels should work well in parallel.

 

[Shoney]

The watts that you "get" are the power that your load (doing work or charging battery) is. Do you have a load of more than the 255w that you have observed? Those panels should work well in parallel.

No load, just straight into Anker powerstation to charge it, gives reading of input from panels

 

[DThames]

No load, just straight into Anker powerstation to charge it, gives reading of input from panels

What model powerstation? Do you have a link?

 

[TomC4306]

How full or empty is the battery?

 

[Shoney]

Heres the link to Anker site for Powerstation

What model powerstation? Do you have a link?

Anker SOLIX F1200 (PowerHouse 757) - 1229Wh | 1500W

Long-Lasting Portable Power Station With a 10-Year Lifespan: With our proprietary long-lasting technology InfiniPower™, combined with LiFePO4 batteries, ul

www.anker.com

 

[DThames]

Heres the link to Anker site for Powerstation

Anker SOLIX F1200 (PowerHouse 757) - 1229Wh | 1500W

Long-Lasting Portable Power Station With a 10-Year Lifespan: With our proprietary long-lasting technology InfiniPower™, combined with LiFePO4 batteries, ul

www.anker.com

Spec says the solar charger should do 300w. As someone asked, what is the battery state when you tested? The battery needs to be largely discharged if you want to charge at max available solar power.

 

[Shoney]

Spec says the solar charger should do 300w. As someone asked, what is the battery state when you tested? The battery needs to be largely discharged if you want to charge at max available solar power.

It was about 80% charged when I did the test, I will repeat with it down to about 10 to 20%

 

[DThames]

It was about 80% charged when I did the test, I will repeat with it down to about 10 to 20%

You will not get strong power to the battery with it at 80%. As the voltage goes up on the battery the charging current will drop right away and foil your test.

 

[JoeHam]

Please check the resource I linked.

You will find that in parallel you will be limited to the voltage of the lowest panel. Current will add but voltage is limited to weakest voltage.

Measure operating voltage of each panel operating by itself. Then put them in parallel to see the effect.

I will guess one of the panels is operating at a lower voltage and limiting the overall output.

 

[DThames]

Please check the resource I linked.

You will find that in parallel you will be limited to the voltage of the lowest panel. Current will add but voltage is limited to weakest voltage.

Measure operating voltage of each panel operating by itself. Then put them in parallel to see the effect.

I will guess one of the panels is operating at a lower voltage and limiting the overall output.

The OP posted the panel specs and the are 0.3v different at max power voltage.

 

[jonathan_winters]

Adding to what others mentioned about parallel/serial, the input on the 757 is hobbled (in my opinion). It only accepts a max of 30V and 10A of solar input.

Most panels I've found will easily put you close to (or above) the 10A limit in a single panel, so putting them in parallel doesn't gain you much. You quickly fly past the 10A limit, and so anything over 10A is not used by the 757.

Smaller panels also run anywhere from 16v to 18v, up to about 24v. So putting even the smallest (16v) panels together in series will take you past the 30v limit, triggering the over-voltage protection (which completely cuts off the solar input).

The best I have done is 2x 100w panels that put out ~5.5A at about 18v -- I'm getting 150w to 170w of solar input, which is enough for most of what I do right now. But it is really annoying that you can't get to the full 300 using any rigid panels that I've found.

It shouldn't be a surprise that Anker's portable panels (read: VERY expensive) come in right at 300w -- according to their support tech, they run at 29V/3.4A... that is such an obscure combination, I have to believe that this was a move on their part to force people to buy their panels to get the most solar input on this unit. That is their choice as the product producer, but it definitely left me with a bit of a sour taste in my mouth once I dug into it a bit... it just seems very unfriendly to users.

 

[Nextone]

Adding to what others mentioned about parallel/serial, the input on the 757 is hobbled (in my opinion). It only accepts a max of 30V and 10A of solar input.

Most panels I've found will easily put you close to (or above) the 10A limit in a single panel, so putting them in parallel doesn't gain you much. You quickly fly past the 10A limit, and so anything over 10A is not used by the 757.

Smaller panels also run anywhere from 16v to 18v, up to about 24v. So putting even the smallest (16v) panels together in series will take you past the 30v limit, triggering the over-voltage protection (which completely cuts off the solar input).

The best I have done is 2x 100w panels that put out ~5.5A at about 18v -- I'm getting 150w to 170w of solar input, which is enough for most of what I do right now. But it is really annoying that you can't get to the full 300 using any rigid panels that I've found.

It shouldn't be a surprise that Anker's portable panels (read: VERY expensive) come in right at 300w -- according to their support tech, they run at 29V/3.4A... that is such an obscure combination, I have to believe that this was a move on their part to force people to buy their panels to get the most solar input on this unit. That is their choice as the product producer, but it definitely left me with a bit of a sour taste in my mouth once I dug into it a bit... it just seems very unfriendly to users.

I've noticed this as a common thing on lots of "Solar Generator" low to mid and systems, a pretty steep limit on Amps and Volts, I build a 200w rigid panel solar suitcase, and found that it is outside of nearly all that type of MPPT equipped system, most are setup to accept their own brand specifically, so a Jackery works with Jackery panels efficiently, Ecoflow works with Ecoflow panels efficiently, but they are not easily switchable/swappable from those V/A limits.