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diy solar

New build sanity check

taltom

New Member
Joined
Jun 16, 2022
Messages
12
Hi all,

I'm working on my first build; a portable generator. I'd like to run the design past you all for a sanity check. Do you see anything wrong or a potential problem? Not really looking for ways to make it power a house. This should be something I can take with me on camping trips. I'll work on a larger "power's out" build next.


SolarGenerator.jpg




Thanks much,
Terry
 
I'd kick that 100a fuse from the battery to the inverter to 120a so it doesn't blow from startup surges. By my math:
1000w/12v = 83.3a * 85% efficiency = 95.8a * 20% overhead = 114.96 which doesn't exist, go for 120a.

If you're speccing the fuse block for its 100a max that would be 4AWG from battery to block, if you're only speccing it for 30a then you're fine. 8AWG tops out at 40a.

Do you have any kind of distribution panel or breaker for your 120v stuff?

Is your controller PWM or MPPT? If MPPT can you go Series on those panels? If PWM you're going to nerf your panel production to 140w max. 10AWG is overkill but not really an issue.

It also wouldn't hurt to kick that battery->inverter wire up to 2AWG accordingly.

By "AC Appliance" you mean a MargaritaMaster-5000, right? :)

Looks pretty good!
 
I agree larger fuse to inverter.

1000W / 12V 0.85 efficiency x 1.25 margin x 1.12 ripple factor = 137A minimum fuse

So I would say 150A fuse.

If this had been lead-acid battery would use 10V min voltage, but for lithium 12V is good.

"ripple factor" is my contribution to the art of calculating current. Current draw from battery is not DC sufficient to deliver watts; current largely follows sine-wave load of single (or split) phase inverter. RMS average current is about 12% higher than mean average current, and represents heating of wire and fuse.

Assuming inverter has any surge capability, fuse should have time/trip curve slow enough to tolerate the surge while remaining well within "must not trip" area.


How long are 4 awg between battery and inverter?
Because you have 12V battery and 120V AC, battery cable should be as short as possible.
 
Thanks for the quick responses. Let me see if I can answer or clarify your questions. While I cannot pack this like a commercial generator, it will need to be mounted in something very portable.

  • Definitely a yes on the MargaretaMaster in the mix!
  • I see the need to increase the main fuse up to 120 or so for sure. Regarding the battery to inverter cables, this will be a compact solar generator, so I expect the distance will be approximately one foot (maybe less), but no more than two feet. The inverter is rated for 1kW with a surge of 2kW.
  • The controller is a PWM at the moment, but that will be upgraded to MPPT before too long. 10AWG cables to the panels are only because that's what I always see used. It should also cover me if/when I add another pair of panels. Probably have a MC4 extension cable or two depending upon need.
  • At the moment, I don't see increasing the 12V draw from the fuse block by much, maybe some DC lighting or something. Although, increasing the cable there isn't a problem either.
  • 120AC devices will plug directly into the inverter or into a three port power strip like below.

3-Port_PWR_Strip.jpg



Many thanks for the help!

Terry
 
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