Fun with a new 100W power supply...

[eccerr0r]

... and that power supply only works if it's outside and the sun is shining on it

Anyone do any homemade stuff with these things? I'm thinking about modding my failed SMPS experiment to be a charge controller for the panel. Should mostly be a software problem though I will have to reconfigure the current measurement circuit a bit and fix some circuit bugs (my charge pump circuit sucks....)

[Agent24]

Re: Fun with a new 100W power supply...

And at first I was thinking... a fault caused by photosensitive semiconductors... like the Raspberry Pi that crashes if you take a flash photo of it...

Then I kept reading and realised.

[eccerr0r]

Re: Fun with a new 100W power supply...

LOL yeah I was intentionally ambiguous as a solar panel would not be considered a power supply in a normal sense, but it is one of those things that really sources electrical power instead of just converting it

Now technically I need to convert the power it supplies to something I can actually use...

(Wording correction...ahh yes it still converts as energy normally can't be created or destroyed...)

[eccerr0r]

Re: Fun with a new 100W power supply...

Funny that MC-4 connectors sort of mesh with banana jacks and plugs... ha...

[r-p]

Re: Fun with a new 100W power supply...

This is my 185Wp powersupply...



Mounted in about an hour (pressed for time, including railings, wiring etc.) last year before driving into the UK during what was pretty much a heatwave.

45V 5A rewired for 22V 10A and hooked up to a China made 24 to 13.8V DC-DC converter (input range 17 to 40V iirc) to feed two Peltier coolingboxes.
It wasn't perfect and when driving through the shade of e.g. trees, you would immediately hear the dip from the fan speed on the coolingboxes. So eventually I hooked them up to the 12V output of the car while driving and only to the solarpanel when stationary (e.g. during walks, the cool drinks after them was worth the extra effort).

Next time I'll make an automatic switch between panel and car 12V circuit, add my 30V 0.2F cap on the 22V side reducing shadingdips, add some 24V 10Ah NiMH batterypack (discarded electrical bike pack, wired as 12V with a separate charging circuit), or all of the above.
Or simply not bother...

[eccerr0r]

Re: Fun with a new 100W power supply...

Yeah I was thinking about attaching a panel to my car to run a drink cooler too, though not sure where to dump the heat from such -- at least running the car's dash fans is a possibility as long as the panel is supplying power. I suspect a sunshade is still necessary to keep the sink temperature as low as possible. The shaded areas is a problem, either have to use the car battery or an auxiliary battery.

I do wonder how the aerodynamics change when you mount it like this... done improperly I suspect it would be one heck of a lot of drag.

[eccerr0r]

Re: Fun with a new 100W power supply...

Step one success! Interfaced a 2N3055 external switch transistor and huge inductor to a MC34063 to get 12V from the panel. It passes enough current to let a 120VAC inverter run without a battery attached and light a 53W (halogen "75W") lamp. Can charge batteries with this without worry of overcharging now! (Unfortunately the 2n3055 gets quite warm at 5A, but that's kind of expected...)

Alas that's not my main goal. I have this old Heathkit MP-10 inverter and want to hack it to...back feed wall power... heh heh heh... some MOSFETs to replace the BJTs...

[r-p]

Re: Fun with a new 100W power supply...

I do wonder how the aerodynamics change when you mount it like this... done improperly I suspect it would be one heck of a lot of drag.

It would whistle when driving above 100km/h or when the wind was hitting it at a certain angle... Then again, many campervans have them mounted on the roof.

Alas that's not my main goal. I have this old Heathkit MP-10 inverter and want to hack it to...back feed wall power... heh heh heh... some MOSFETs to replace the BJTs...

Obviously you know that an inverter or a grid-tied-inverter is a humongous difference.
I do not know your expertise level, so I might be insulting you, but for me as an EE this is something I wouldn't even contemplate trying...

[petehall347]

Re: Fun with a new 100W power supply...

simple matter of matching the sine waves . i heard there is a loud bang if not exact match .

[eccerr0r]

Re: Fun with a new 100W power supply...

Sometime I wonder if it would be more aerodynamic if somehow you made the panel flush to the roof and added air blockages. Having the gap must be really bad.

I ended up throwing out the MP-10 conversion idea mainly because... I can't guarantee I can get the voltage high enough and not scalable. It wasn't the grid tie aspect that I was worried about ... at least, yet.

But I have a different idea now on how to get the voltage which would make it easier to get to MPP when grid tied... thinking, thinking...

(and hopefully no loud bangs, heard or not.)

[KvnTM]

Re: Fun with a new 100W power supply...

I can remember that my dad's Audi A6 has solar panels in the roof to run the dash fans in summer. The solar TEC cooling boxes are a genius idea for summer. We went over 40°C that summer here in Germany. If there was an elegant way I'd do that to my e39 bimmer.

I really don't want a gigantic solar panel on my car I guess it makes a lot of noise or undergo "sudden violent self disassembly" when going - lets say - 200kmh.

[eccerr0r]

Re: Fun with a new 100W power supply...

Well, got more "power supplies" to play with. Hoping to play with voltage instead of current...

except now found a new concern: voltage too high for the power supply itself

Looks like I will have to design another architecture, or just burn the power via voltage dropper resistors... (no capacitive dropper, sorry, this is all DC...)

Ahh... fun of design...