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ryanm
Senior Member

Joined: 25/09/2015
Location: Australia
Posts: 202

Posted: 05:52am 26 Mar 2018

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Hi Guys,

I'm making a diy solar setup at my house mostly because of grid unreliability, slightly because I like to tinker (no relation). There's a few buildings on the same meter so I'm still going to have grid available to me if I need it.

I've recently come by a free used POE switch which has a 53V 14A output circuit. (13.25 per 12v battery on my planned OzInverter). I was thinking about using this when required overnight to prevent the batteries from discharging too deeply, then they would get a proper top up charge with a solar MPPT charger during the day.

Just though I'd float the idea before spending too much time on it. Anybody see a reason it wouldn't work?

oztules

Guru

Joined: 26/07/2007
Location: Australia
Posts: 1686

Posted: 07:41am 26 Mar 2018

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Yes it will work... but you will probably use too much night power than you need ( battery size will count in this calculation.)

Preferably i would use a few of the 48v led drivers on ebay fpr $41 or so. This way you can control the voltage set point to tenths of a volt. I would set it for somewhere around the 49-50v mark..... something like this:

https://www.ebay.com.au/itm/DC-48V-10A-Universal-Regulated-Switching-Power-Supply-for-Computer-Project-N/282866219993?ep id=20015755974&hash=item41dc23fbd9:g:rycAAOSwjT9al4d0

This will give you 20 amps ( 1kw) at your desired voltage ( you choose what works for you... or use more etc. ).

You can buy smaller units if you so wish, so you can switch them separately in , depending on the weather

...oztules

Edited by oztules 2018-03-27

Village idiot...or... just another hack out of his depth

ryanm
Senior Member

Joined: 25/09/2015
Location: Australia
Posts: 202

Posted: 08:27am 26 Mar 2018

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Thanks for the reply oztules.

Just realised I didn't mention I'd control it with an MCU and only switch on if the batteries were getting down. Most nights I'd aim to just have my fridge and maybe a fan going. Hoping I can offset a fair bit of that with wind.

Current working theory is turn the house into an ice-box from noon till dusk then open the windows when the breeze outside is cool. On the really hot nights I think the output from the power supply should match up fairly well with the electrical demand of a 3.5kW split. Putting in a smallish SLA setup since I have grid backup with the reasoning that in a few years when they're getting tired lithium will really be in it's stride.

I've got a few box A/Cs lying around and a harebrained scheme to make an ice thermal storage cooler, but I'm going to have to kick this food and shelter addiction before I have enough spare time to look into that...

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