Suggestions for use of 319V 100W Solar Panel?

[Mike90250]

I get no hits for KR1212C, so I can't help. I'd say test it out for a couple days before you head off to the deep jungle. Also note they are SOLAR panels and need direct bright sun. any shadow on even a small part of the panel will shut much of the power off.

[Allan Michaud]

I couldn;t find anything googling that number either. The guys in Germany that I bought them from specifically asked what output voltage I would want and seemed to know exactly what I would need. But I will be testing to make sure the output is 14.5v before I try plugging it into the controller. So far everyone I have showed it to here seems to think it should work as I expect. What I really like is how small the panels roll up, they fit in a 12cm diameter pipe less than 2 feet long.
Thankfully there tend to be clearings in the forest. It's not been an issue up to now and I hope my new mppt controller will help. This is a hell of a lot bigger than I have tried before though and I am very wary of the voltage. I am basically putting the 319v-14v converter and controller in a very well ventilated box, to keep all the connections neat, tidy and hopefully safe. The cables from the panels then just plug into connectors on the box. As it's proved impossible to find any quality cables here I have had to suck it up and just ordered some properly insulated 2.5mm cable from neighboring Thailand, along with 2 Y junctions and some mc4 diode holders, which solved another issue of where to put them. I think I have it fairly well covered and 180w should be double what I need so I'm reasonably confident it will work. I will be testing it thoroughly.

[Perfektum]

Hi,
I don't know if anyone is still interested, but I got one of these panels to use as a lightweight camping power supply charger, and needed to solve the high voltage problem. As I am a bit of an electronics geek and an embedded software writer I did that with DIY kit, ending up with an MPPT inverter which I built and programmed myself specifically for the panel. I could tell people about it, as well as the things I learned about what definitely will not work with this type of panel, if anyone is still interested?

Hi I'm interested in your DIY kit

Best regards
Simon

[Perfektum]

Maybe one can use this dc/cd

TDK-Lambda PH300F280-15. Input: 200-400V, 1.88A. Output: 15V, 20A. 146 x 86 x 12.7mm. Baseplate temperature -20°C to +85°C. UL, CE.

http://www.allelectronics.com/make-a-store/item/dc-1520/15v-20a-dc-dc-converter/1.html

[Evanspatrick]

Since someone has asked for more info on my experience with one of these panels, here it is…

First off, never ever forget that the panel typically puts out around 405 volts, open circuit, when it’s in the sun. Very definitely a voltage to take seriously, and absolutely not one to take unknown risks with. I don’t think you would want it anywhere near a boat, unless you had some very competent waterproofing, or within reach of dogs who like to chew things. Very small amounts of water getting into the circuitry will cause fizzes, bangs, and smoke.

The high voltage, however, does indeed make it possible to use thinner, lighter cabling, which was important for me. The current coming from the panel going at full whack is less than 0.4 Amp, which means that more or less any cable which has insulation rated for the high voltage will be thick enough.

I would (speaking just for myself) be pretty relaxed about using most normal UK mains cable (240v rated), and 1mm would be more than ample thickness for any reasonable length of cable (perhaps hundreds of metres). It is quite possible that official regulations would say differently, so I am speaking just for myself. Bell wire would very probably not have a high enough insulation rating for the voltage.

I use my single panel as a roll-up 12v battery charger for camping, and it works extraordinarily well for this, though it needed some non-trivial custom electronics work to make this possible. I couldn’t find any practical off-the-shelf solution (other than hugely expensive and heavy kit), and I looked quite hard.

It may well be possible to use an off-the-shelf mains Power Supply Unit (e.g. a 240v AC to 15v DC power supply for LED lights, from ebay) to transform the panel’s output to a lower voltage. Some modern PSUs some can cope with that high input voltage (which is up to about 420v worst case), and all can cope with the regular mains peak voltage of 350v or so. Almost all of them will also work equally well whether the input voltage is AC or DC.

I have a few PSUs lying around my workshop, and, when I looked inside, about half of them use components which are rated OK for the higher voltage. They are super cheap (under £11 for a 100w unit). I tried one which used components not rated for the higher voltage (just to see what happened) and one of the capacitors inside did actually explode. It was quite an exciting moment.

Since the output voltage of the panel drops right down (to less than 320v) when any significant power is being drawn, it was possible to put together a simple electronic voltage-limiting circuit to go inline with the panel’s output that keeps it always below 350v, which makes life simpler. I would guess that, if a PSU has been sold to as a package with the panel, it will be one that only includes components that are OK with the higher voltage.

The big problem which I had with the off-the-shelf PSUs which I tried was that every one of them is very much designed to be fed with a more solid input voltage than you get from a solar panel.

The main result is that if you try and pull just a tiny bit too much power they go into a cycle of repeated voltage collapses, once every second or two, as the PSU tries to pull more power from the panel than it can supply, causing its output voltage to drop to almost nothing. I suspect that most modern PSUs with a fixed output voltage will do the same.

A battery being charged in a situation like this is usually greedy for as much current as it can possibly get, and I found that the combination of an off-the-shelf PSU and an off-the-shelf charge controller really didn’t work at all well, either supplying much less current than the panel could produce, or going into those voltage collapse cycles.

To fix the problem I put together an additional supervising controller for the PSU to keep the output as high as possible, without causing voltage collapse – a classic Maximum Power Point Controller in fact. This needed more electronics and software development than I could ever really justify.

With this setup, I get charging rates which I found surprisingly high – up to about 75 watts measured at the battery (e.g. 5.4 amps at 13.8 v).

I would hope that, if a PSU has been supplied with the panel, it will be one which behaves much better as a solar panel voltage dropper than the ebay-off-the-shelf ones which I tried. I would be quite interested to know.

[Potts]

Hi Patrick,

I picked-up one of these solar kits a few months back for a good price from viktor.7800 on ebay: http://www.ebay.co.uk/itm/371620533810
It comes with a 400w DC-DC step-down controller, taking the flexible panel voltage from 400v down to 14.5v. I only use two of the flexible panels connected (in parallel) into to the step-down controller. This in turn feeds its fixed 14.5v output into a cheap PWM solar charge controller, providing a charge to the battery and separate 12V load.

I've only recently got it set-up and time will tell how good it is at maintaining the battery charge. However, I'd be happy to oblige if you'd like any readings/tests undertaking on the step-down controller. The cheap PWM solar charge controller is already displaying some anomalous readings and I'm inclined to pick-up a better quality unit - at least something that's selectable between different types of 12V battery.

Richard

[alzoobery2001]

Thank u . For ur reply about fuji solar . Are u the seller ? But the price is expencive , there are cheaper than this price , if u now other this seller please tall me , What is ur phone number, this my whatsapp 00967712927117

[Allan Michaud]

I got my 2 panels up and running. I was over complicating matters. I was trying to run through an mppt controller when that was not needed as the converter is only putting out 14.5v, so you can't over charge the battery. It works just fine with some heavy duty cable I tried but I have just bought some much more lightweight cable that is properly rated at 400-750v. This will enable me to lose 2 connectors so I am hoping I might see an improvement. In the middle of Phnom Penh on a fairly sunny day we got 8.5amps with the first cable, it was a little hazy so maybe we could get a bit more out of it. I hope with the new cable and less connectors to get at least 10amps, but 8-9 is enough for what I require so I am very happy with it.
Basically I have 2 panels which I connect to the converter which outputs 14.5v to the battery. The panels roll up into a 6 inch pvc tube (21" long) and the converter and inverter are both small so it all fits easily on a motorbike. I could not be happier having read some doom and gloom statements on here about my chances.

[yojamey]

Good to know

I see this seller in Holland who sells the Fuji fwave panels and DC to DC step down voltage gizmo and charge controller

http://www.ebay.com/sch/viktor.7800/m.html?

[Solananas]

Hi
Happy you found something to use these panels normaly.
Could you post a picture of this converter ? it is 200w power so. How much it costs.
Did you buy it on Pollin?

[Solananas]

it looks same spec.

Sortie 15 V/DC / 13.4 A
200 W Puissance
Entrée 88 - 264 V/AC, 125 - 373 V/DC
avec potentiomètre

something i dont understand it's ACDC and DCDC step down.

http://www.ebay.com/itm/DC-DC-400W-s...-/351822805787 :
are you sure it needs custom to work with high voltage panel cause it's very similar in design with normal ac/dc converter.
http://www.ebay.com/itm/12V-DC-30A-3...V/121352224204
because it's far less expensive.

[PNPmacnab]

As to the AC/DC issue, the peak voltage or DC voltage is 1.4 times the RMS listed voltage. Some power supplies use a capacitive voltage doubler that requires seeing a voltage in the opposite direction in order to work. My system has a 50V DC buss and many 100-240V electronic wall warts work fine (at a little lower power) at this voltage. I have defective inverters that I just ripped out the H bridge that makes the AC and just run TV, CFL and DVD electronics on 140V DC. I'm in the US so 120V AC is normal.

So many switching power supplies may work on a high enough DC voltage. Higher voltage up to the maximum result in lower current. Charging a battery with a switching power supply can exceed a panels power output and cause repeated shutdown of the converter as the panels voltage drops. I use a number of standard buck converter like those found on ebay. A rather simple circuit can allow these converters to operate at a panels power point. A sense circuit monitors a panels voltage. When a panels voltage drops, it fakes the power supplies feedback loop into thinking the converters output voltage is too high. This reduces the charge current to a level the panel can support.

[Allan Michaud]

Solananas Here are 2 images, it came with the panels, I didn't buy it separately. It converts the around 400v down to 14.5v, ideal for directly charging a 12v car battery. It's Chinese made as you can see. I only paid EIRO's55 for each panel and this was given free as part of the deal. Sending them here to Cambodia cost almost as much as the panels.