# Convert 320VDC to 230VAC or 48VDC voltage using 230VAC (UK) UPS?

I live in the UK where mains voltage is 230VAC and also might buy an electric engine which would run at 48VDC.

Would a UK voltage (230VAC) UPS be able to step down the 320VDC to either 230VAC or 48VDC for use on a boat?

I'm thinking I could connect 12 panels in parallel and use either;

Double-conversion UPS to deliver 48V by bypassing the conversion from the battery back to 230V

or

Line-interactive UPS to deliver 230V directly from the 320VDC.

The question is would the UPS's surge protection be able to deal with the high voltages? (Keeping in mind the sun isn't real bright in the UK).

Also with regard efficiency will there be a lot of power loss in the system? I don't really know how surge protection from overvoltage works in UPS's and assume it uses some kind of buck conversion...? I'm guessing that the surge protection circuits might struggle with continued voltage overload. Does anyone know if this would be the case?

The question is, will the UPS's be able to reliably deliver either 230VAC or 48VDC?

Here are the specs for each individual panel;

http://www.innoasia.net/2010/pdf/presentation/SmartCity_Takano.pdf

Open circuit voltage(Voc): 429V
Optimum power voltage(VMP):319 V
Short circuit current(Isc): 0.39A
Max operating current(IMP): 0.288A
torrence:+_5%
Maximum system voltage: 1000V
THERMAL CHARACTERISTICS: (-25 ° C to +90 ° C)
Temperature coefficient ÉÂÂÂIsc +0.08%/ ° C
Temperature coefficient ÉÂÂÂVoc -0.35%/ ° C.
Temperature coefficient ÉÂÂÂPmax -0.15% / ° C.
Over-current Protection 30mA

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iceng3 years ago
Sorry to be a downer .... but after twice reading that PDF
That solar panel is a promo Vapor ware product ie does not exist

Test my evaluation by simply buying one ( they roll up into a 10 cm tube )
Or maybe borrow a sample of that 12.5% efficiency flex for UK distribution.

A
mchin2 (author)  iceng3 years ago
I will have one of the panels next week. With regard "12.5% efficiency flex for UK distribution" ? Are you referring to the aforementioned panels or to something entirely different?
3 years ago
Page 46 of the vapor ware PDF purports that the
"Next Generation Flexible Solar Cells"
will achieve 12.5% efficiency
A bold claim when the theoretical  peak PV eff is slightly over 13%
Also implies the present panels are less efficient.

The only case where this eff is exceeded occurs
when a visible light pv cell is placed on an IR cell
thereby combining two cells in the same area and
adding the efficiency to a peak of 26%
Thus far these cells are only available for space and military applications.

I'm curious about  the panel specification
• Optimum power voltage(VMP):319 V DC
• Max operating current(IMP): 0.288A = 288ma
• Does Not Jive With
• Over-current Protection 30mA ??!?

Do you know what are the size dimensions including weight of this panel
that can provide over 90 watts in full sun. ( 91.8W = 319V × 0.288A )
mchin2 (author)  iceng3 years ago
11 months ago

Helloo, sorry to bring up old ideas... but did it work???

I'm keen to get a couple of panels going, but not sure if you ever managed to convert to 220 or 48 ?

Many Thanks

M

3 years ago
3.4m long. I'm impressed. They're a Fuji subsidiary, so the stuff should be OK.
watvaz3 years ago
I send a email now to this guy, so he can show to all this sort of dc/dc step down. Hope all of us give help in this matter. There is light, and i can see it.
watvaz3 years ago
I have the dc/dc inverter. Tell me where are you, so i can tell my suplier to talk to you and make a order. ease.
steveastrouk3 years ago
No, its not a feasible approach.

You need a Solar inverter - grid-tied or not.

UPS inputs, from the DC side are rarely more than 48V.
mchin2 (author)  steveastrouk3 years ago
The UK type UPS normally receives 230VAC from the mains which is converted to 48VDC for the battery. In other words instead of plugging the UPS into the 230VAC UK mains, I'd plug into the 320VDC of the solar panels. I'm thinking that 320VDC it may be tolerated due to the overvoltage protection of the UPS.
3 years ago
Its a cute idea, but your OC volts on the cells is definitely too much for a UPS input, and the conventional UPS is NOT designed to handle an input from 0 to 400+ volts, its designed to deliver over the input range its built for - 220 +5-10%

I think it will do "something", I just don't think the input is designed to do what you want.
mchin2 (author)  steveastrouk3 years ago
Alas the only invertors I've been able to find handling 320V costs thousands which kind of negates the good luck of coming across these solar panels... Any other possibilities?
3 years ago
Thousands ? For a 1kW inverter ?
mchin2 (author)  steveastrouk3 years ago
Ahhh yes I guess you're right. My mistake... I've been looking at solar controllers that take high voltage inputs and they tend to be pricey. I guess solar inverters like the Sunnyboy series are a bit less expensive and take a variety of high voltages. But shouldn't an inverter be placed after a solar charge controller? Also what if I want 48VDC current for charging 48VDC batteries and running the electric engine?
3 years ago
They're going to be tricky to handle, short of designing your own high power, high voltage MPPT solar charge controller. Its not a trivial problem, and judging by the amount of sweat on my forehead, not one I'd care to contemplate making as a one off....
mchin2 (author)  steveastrouk3 years ago
What do you about cutting the cells into 6 pieces and resoldering in parallel? 48V might be a bit more user friendly with regard finding a compatible MPPT charge controller.
3 years ago
Very clever idea " I think the termination technology might be very tricky, unfortunately.

Have you got an old UPS to try out ? I haven't been able to find real circuit diagrams of the input stages, though I've only had a cursory look.
mchin2 (author)  steveastrouk3 years ago
I've got an old UPS in storage. I'm thinking for safety's sake maybe cover the solar panels with lightweight tape, plug into the UPS and gradually pull away pieces. I'll also ask the neighbors to look out for any flashes of lightening or clouds of smoke and get ready to call 911! Maybe I'll pray too.

What do you mean by "termination technology" ? Is there something I should know?
3 years ago
Hello
I have these panels here in Brazil, and done lots of tests. Need to share info. Have step down for batteries, and study for grid ties.
mchin2 (author)  watvaz3 years ago
What step down is it that can handle these sorts of voltages and what is the price range?
3 years ago
Only that you can't cut these panels up and solder extra wires to them.

I'd use cardboard to cover the cells if I were you.
3 years ago
What are you getting ? I'm intrigued to see one. Is it self-adhesive ?
mchin2 (author)  steveastrouk3 years ago
3 years ago
NICE. Great find.
Joe True3 years ago
A 230VAC, that's "AC", input is quoted as 230V "RMS". That means a (sine
wave) peak value of
230 x 1.414 Volts which is approx 325Volts.

AC enters the SMPS through a filter and is rectified (turned to DC) and that
voltage (325-ish minus a couple
of volts across the rectifier) is stored on a "reservoir" capacitor.

I suggest that an input of 325V "DC" would amount to the same thing. The
only caveat I can see is there is
a 100% duty cycle on 2 of the rectifier diodes which may be problematic.

The off load output (or open circuit) of 429V cannot be ignored as SMPSs
present a low/very low impedance
when not supplying a load so you would have to use a power supply that takes
an input of AT LEAST 305VAC
(429 x 0.707) AND can operate below 225V though SMPSs usually have quite a
range of operating voltage.

I don't envisage a problem with voltage spikes as the system wouldn't
produce them. The maximum panel
output is 429V and is a feature of the construction of the device. The
supply could only "surge" up to that level
if there was enough light and no load on the SMPS.

Of course you really have to look closely at the spec and graphs as there
can be hidden pitfalls in the actual
operation of any device.