Choice between Powertech vs Kings solar panels

aastek · Veteran Member

Choice between Powertech vs Kings solar panels

dorian · Guru

This panel appears to be correctly spec'ed in terms of power output:

https://www.ebay.com.au/itm/Adventure-Kings-160w-Solar-Panel-MPPT-Regulator-10m-Lead-Solar-Panel-Extension/173770380578

... but like most vendors, the seller mangles the terminology:

"The newly upgraded, premium Adventure Kings 160W Folding Solar Panel with MPPT regulator can delivery an incredibly powerful 12.8A of power per full hour of sunlight"

The output voltage at max power is not specified, but it must be ...

Vmax = 160W / 12.8A = 12.5V

This low voltage means that the panel is unsuitable for use with a PWM regulator. That's why it comes with an MPPT type.

I would prefer a panel with a higher output voltage (~18V), in which case the current would be around 9A. Provided that the regulator is mounted near the battery, this lower current would result in a lower voltage drop in the cable.

-- Edited by dorian on Sunday 14th of March 2021 07:05:35 AM

Tony LEE · Guru

12.8 amps is into the battery - hence your figure of 12.5v, not out of the panel, which is going to be 18 volts. That's what mppt controllers do

dorian · Guru

Tony LEE wrote:
12.8 amps is into the battery - hence your figure of 12.5v, not out of the panel, which is going to be 18 volts. That's what mppt controllers do

How do you charge a battery at 14V if the regulator output maxes out at 12.5V?

Also, if you look through the gallery of images, no two images are of the same panel, so we can't count the cells???

-- Edited by dorian on Sunday 14th of March 2021 08:45:53 AM

Whenarewethere · Guru

MPPT controllers need 5v more input than the battery. They do some tests for a minute or two when first turn on. Far better to have 2 panels in series for 36v, especially early in the morning or overcast weather. The controller really needs to be next to the battery.

dorian · Guru

Whenarewethere wrote:
MPPT controllers need 5v more input than the battery. They do some tests for a minute or two when first turn on. Far better to have 2 panels in series for 36v, especially early in the morning or overcast weather. The controller really needs to be next to the battery.

Depending on the topology, switchmode controllers are able to boost the input voltage, so it is quite conceivable that the output voltage is higher than the input.

I expect that the tests would involve sensing the voltage and current from the panel and perturbing the current draw while computing the input power. This would establish the initial MPP (maximum power point). The regulator's MCU would then monitor these same parameters at periodic intervals, and adjust the MPP to suit.

-- Edited by dorian on Sunday 14th of March 2021 09:11:24 AM

Jaahn · Guru

Hi smile

Probably the Kings is better. Cheaper anyway. aww

If it is this one below it should be OK. But I doubt the cheap MPPT is really what it says. You do need to pay more than all that for one that works as MPPT. But it still should work as a PWM regulator. The 99% efficiency gives the scam away. Common claim for cheap regulators. I am not sure where this BS comes from " delivery an incredibly powerful 12.8A of power per full hour of sunlight" MAGIC perhaps

12.5 KGs is a bit heavy to lug around regularly unless you are fit and able ! disbelief I do not like folding panels.

Jaahn

And Dorian none of the MPPT regs claim to boost the voltage above the panel voltage. That is possible but they do not claim to do that normally, just boost the current when the battery voltage is lower. And indeed most cheap ones do neither but are PWM in a relabeled case ! Usual scam found everywhere for sale! furious

Kings Premium 160w Solar Panel with MPPT Regulator Massive 12.8amp Output 99% Efficiency

Specifications - Solar Panel

Rated Maximum Power (PM):	160W
Tolerance:	± 3%
Voltage at Pmax (VMP):	17.6V
Current at Pmax (IMP):	9.1A
Open-Circuit Voltage (Voc):	21.0V
Short-Circuit Current (Isc):	9.96A
Normal Operating Cell Temperature	47°C ± 2°C
Maximum System Voltage	1000VDC
Maximum Series Fuse Rating	15A
Operating Temperature	-40°C to +85°C
Application Class	Class A
Connections	Quick-Connect Style Fittings
Dimensions (Open)	1340mm (width) x 670mm (height) x 30mm (depth)
Dimensions (Closed	670mm (width) x 670mm (height) x 65mm (depth)
Weight	12.5kg

-- Edited by Jaahn on Sunday 14th of March 2021 10:17:48 AM

dorian · Guru

What about this step-up MPPT regulator?

https://www.dhgate.com/product/mpt-7210a-mppt-dc-dc-step-up-power-solar/399875259.html

Just FYI, here is an IC targeted at low voltage MPPT applications:

https://www.st.com/en/power-management/spv1040.html

Whenarewethere · Guru

When I look at the price point of these products something has to give, & it's probably a bit more than just wiring.

The 160 watt PWM model I would suggest the wiring is a "touch" undersize! My guess is about 14awg wire at best, so there goes 10% of your power straight out the window over 6m (12m + & - )

My 20 amp MPPT was over $200, let alone 6awg & 4awg wire, plugs & solar panels.

Screenshot_20210314-110650~2.png

Stewart · Senior Member

Hi I have 2x 200 Kings solar blankets each waying approx 7k weight. Extremely easy to store in tug or under bed. I get average 8 - 10 amps when both connected to dc dc charger through Anderson plug. I find this enough to recharge 100aph battery quickly. I also have a spare 120 watt solid panel I can connect to a separate connected controller, if I need more on a cloudy day. I see these are on special at present about $189. Cheers Stewart

Stewart · Senior Member

Kings specials https://marketing.4wdsupacentre.com.au/210314/ViewOnline.html

Whenarewethere · Guru

My 6 x 20watt Projecta panels I get 7.8amps (I have 2 in series so 3.8amps). Out of the MPPT usually about 9amps without difficulty. But under ideal conditions & cool panels up to about 11amps, the highest was 11.3amps. The 120watts of panels can output upto 137watts, but usually about 127watts.

So with a quality setup 9amps from 120watts is an easy target.

Bicyclecamper · Guru

I would go with the Powertech, and just change the regulator to a MPPT quality one. I have a Powertech 80 watt folding with pwm, had it for 6 years, and it is perfect for my battery. Though I only use max 12 amps per night, so 3 hours is all I need to get them back. But the panel is consistant, and even gives good charge when overcast or filtered cloud cover. I swear by Jaycar panels.

-- Edited by Bicyclecamper on Sunday 14th of March 2021 01:38:03 PM

Jaahn · Guru

dorian wrote:
What about this step-up MPPT regulator?
https://www.dhgate.com/product/mpt-7210a-mppt-dc-dc-step-up-power-solar/399875259.html
Just FYI, here is an IC targeted at low voltage MPPT applications:
https://www.st.com/en/power-management/spv1040.html

Hi Dorian smile

Why would I go scouring the worlds cheap suppliers to find a step up MPPT from a supplier that I have never heard of ? Sorry ! confuse Any comparison tests done ?

If you want to get a good setup that has extra charging 'benefits' then you get a panel which puts out more than enough voltage, eg 20-30V nominal output, possibly two 12V in series or a 170-190W house panel which you can get for $40-50, and get a MPPT that I know actually works and is not a cheap scam MPPT that does not. Sorry but it is all a waste of time and effort and most folding panel sets are overpriced and poor quality IMHO. BUT a good sales campaign can sell anything. cry

If you do not have excess voltage then just use a PWM reg and save the money and hassel. If your wiring is substandard and the reg is on the panel you will be no worse off. disbelief Which is damming it with faint praise. But any panel that does not put out enough voltage and needs it boosting is just unsuitable for charging batteries. Why go there ?

Stewart said --" 2x 200 Kings solar blankets ---- I get average 8 - 10 amps when both connected ". The maths do not add up do they !

Jaahn

Just for the record I believe there are great steps in the quality of MPPT regs in those that do actually work. The better ones do get to the Power point faster and scan faster to stay on it as things vary some days. They have good software to extract the max power and good hardware to minimise losses. Just like the grid connect units do. You never see a PWM unit in a grid connect house unit.

Whenarewethere · Guru

The 2 x 200w blankets at 8 - 10amps. The advertising states up to 16.3amps. So 32.6amps less 10amps, so 22.6amps seem to be hiding somewhere!

-- Edited by Whenarewethere on Sunday 14th of March 2021 05:42:06 PM

Tony Bev · Guru

As a part time traveller, who is not on the road full time

For any costly items, I always try to buy from a shop, as if they do not work, or are damaged in transit, I can easily take them back

dorian · Guru

Jaahn wrote:
dorian wrote:
What about this step-up MPPT regulator?
https://www.dhgate.com/product/mpt-7210a-mppt-dc-dc-step-up-power-solar/399875259.html
Just FYI, here is an IC targeted at low voltage MPPT applications:
https://www.st.com/en/power-management/spv1040.html
Hi Dorian
Why would I go scouring the worlds cheap suppliers to find a step up MPPT from a supplier that I have never heard of ? Sorry ! Any comparison tests done ?
If you want to get a good setup that has extra charging 'benefits' then you get a panel which puts out more than enough voltage, eg 20-30V nominal output, possibly two 12V in series or a 170-190W house panel which you can get for $40-50, and get a MPPT that I know actually works and is not a cheap scam MPPT that does not. Sorry but it is all a waste of time and effort and most folding panel sets are overpriced and poor quality IMHO. BUT a good sales campaign can sell anything.

ISTR that this question was discussed in another thread, but I tend to forget things nowadays.

Anyway, I now believe that these step-up MPPT regulators are really only useful when you are using a 6V panel to charge a 12V battery, for example. The MPP of the 6V panel occurs at 9V, so the MPPT regulator would be able to step it up and then deliver the maximum panel power to the battery at 14V, albeit at reduced current.

The same cannot be said for a 12V panel. Its MPP occurs at 18V, so at a voltage of 12V, say, its output power would be negligible. The MPPT regulator would then be delivering 100mA, say, to a 14V battery. Not much point in that.

Jaahn · Guru

Hi Dorian smile

I know you have a technical interest in these things so possibly I will start a bit of discussion in another thread, as it it does not help the OP here. biggrin

MPPT is a term that is used for any regulator/controller that is not a simple PWM unit and it is not really a good indication that a regulator/controller is good quality. hmm

Jaahn

Stewart · Senior Member

2x200 watt blankets. Yes I agree it seems wrong but that was away last weekend with a quick test. I just layed them on ground without much attention. Then checked the gauge. I had setting up to do and didn't get time to test them I need to run a few tests on cables etc next time. One was a brand new replacement for one that failed. I am sure I can do better with a bit of effort. Caravan us kept in storage 400 km from home so I won't get a chance till next trip. Wasn't an issue at the time as battery was showing 90% when we got there. But I did wonder. Cheers Stewart.