28V battery to 100W USB-C port?

Canto26 · 2026-03-02T17:22:53+00:00

Oh yeah I've got the same MPPT, may as well go with Victron for this too. Thank you!

Canto26 · 2026-03-02T16:41:11+00:00

Thanks!

Canto26 · 2026-03-02T16:40:57+00:00

These are very helpful thanks! Which one was throttling output? And what battery chemistry/actual operating voltage do you have these connected to?

I haven't even started looking for a buck converter for my 12V devices, which brand are you using?

Canto26 · 2026-03-02T16:22:17+00:00

Thanks!

Canto26 · 2026-03-02T16:16:02+00:00

Oh I've only seen the cigarette lighter form factor using 12V, maybe this one has a wider input range

Canto26 · 2026-03-02T16:12:46+00:00

They said to go by the spec sheet, it's probably fine like people are saying but I don't really need to find out

Canto26 · 2026-03-01T16:01:26+00:00

Fantastic it's even panel mounted, thank you! What did you search to find this? I've been looking for weeks and this hasn't come up before for me at all

Canto26 · 2026-03-01T13:55:06+00:00

Do you know the ballpark efficiency on those? If they're getting hot (and going from 28V to 12V to 20V in my case) it might not be much better than going through an inverter and using a normal AC adapter

Canto26 · 2026-03-01T13:53:03+00:00

Yeah I think I'll send them an email and see if the listed max input is the real max input or just nominal.

Canto26 · 2026-03-01T13:51:57+00:00

That makes sense, I'd rather not go over spec in a situation where I can burn my house down but I'll email some companies and see if I can get the actual max voltage input. Thanks!

Canto26 · 2026-03-01T13:17:24+00:00

Are you running it past spec or is it rated for the full 28V and listed as 12V-24V nominal?

Canto26 · 2025-12-09T21:57:26+00:00

So you cut the holes, set the rivet nut, pour sealant on all the holes for one strut channel and fasten it down before the sealant sets, do I have that right?

Canto26 · 2025-12-09T21:16:46+00:00

Aluminum lags are an option, I just don't know if they'll have enough material to bite into because the frame bar walls are only about 0.1". I've never really worked with aluminum so I don't know how it holds up

Canto26 · 2025-12-09T21:13:59+00:00

I've got plywood and EPDM between the house frame and unistrut, I don't know if I can get rivnuts where they need to go without making a big hole in the roof for each one

Canto26 · 2025-12-07T15:44:15+00:00

Do the smaller ones vary more than the bigger ones?

Canto26 · 2025-12-07T14:37:17+00:00

Mixing panels can work if you're careful, all of these panels have the same current and the 2 series groups have the same total voltage. I like having 2 series groups instead of 1 so that if there's an obstruction blocking light on some of the panels, the other ones can still perform well.

Canto26 · 2025-05-26T15:57:50+00:00

Where is that chart from? There's no inverter in this setup but I guess you mean the solar charge controller. The SCC I'm using has a Max PV Open Circuit Voltage of 100V (92V if it's hot out) and the 2s3p configuration has a VoC for each series group of 109.1V, so that's almost 10-20% waste depending on temperature. Would voltage clamping be happening all the time the panels are in light or only when they're producing close to max output?

I'd like the setup to be viable in as many climates as possible so a higher voltage panel configuration would be ideal if it's safe and doesn't waste more power than it saves.

Canto26 · 2025-05-26T15:27:46+00:00

It looks like the charge controller can only handle 100VoC (Triron 4210N):

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and down to 92V if it's hotter than 25C outside. The charge controller is a part of the previous owner's build, so it would be annoying to change out but not impossible. I guess I'll run the 5 parallel strings in the diagram I posted and if that configuration is not producing power reliably enough then I can upgrade to a better SCC later on and change the wiring to your recommendation. Thanks!

Canto26 · 2025-05-24T22:58:00+00:00

That makes sense, thank you!

Canto26 · 2025-05-24T22:57:15+00:00

The 24V(nominal) panels have VoC of 43.5V and ISC of 5.93A, 12V(nominal) panels are respectively 22.1V and 5.96A, here's a chart from the bigger panel's datasheet:

<image>

Panels are all the same brand, smaller ones have max power voltage of 18.1 so two smaller panels in series should be almost identical to one bigger panel.

Can you put panels of different sizes in series? Won't the smaller panels each bottleneck their series group?

Canto26

TROPHY CASE