48V Inverter/Charger Selection Help for Shed

jmssmth

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Sep 8, 2022
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I got a deal on 4 solar panels to electrify my shed (specs below). Plan to build my own 16 cell battery with LiFePO batteries. Looking for some help spec'ing out the charger/inverter. I like simplicity and low cost of most AIO's, but I would go over the 145V max voltage for most ~3000W AIO's on the market. I only need 120V for now, but would like at least retain the ability to scale to 240V with whatever I start with. I want to eventually plug into my generator inlet box on my house during outages and need 240V for the well pump. One thought I had was to buy this refurbished Growatt SPF 3000TL LVM-48P for the inverter and generator A/C charging functions and the SmartSolar MPPT 250/60 for the actual solar charging. A second option would be to get this refurbished SPF 6000T DVM-MPV. It wouldn't be stackable and standby usage would be a decent amount more. Thoughts? Suggestions?

240W
Voc: 37.2
V at Pmax: 30.4
Isc: 8.37
I at Pmax: 7.89
 
If you're planning to start a well pump you should look for a LF inverter.
I've been fairly happy with my TP6048 since October. No issues with the well pump at 300'. Lights flicker a bit starting the 1hp air compressor if it's charged up.
My biggest complaint is the lights flicker when my washer agitates and the idle consumption is excessive.
I ordered direct from SGP.
 
I did think of that, and perhaps I am overthinking it (as I tend to do). Wouldn't that restrict the amount of hours I could collect energy if I went with a 2s2p array? I barely get more than 2 peak sun hours in my area, during the winter, based on online calculators.
 
At the end of the day watts don't change regardless the Volts and Amps configuration , it's a law that can't be changed.

The TP6048 mentioned above would allow you to go 4s. The only issue you might run into is the minimum voc to keep the mppt happy, a 5th panel would solve that. I'm running 2 9s strings ~360voc.
 
I did think of that, and perhaps I am overthinking it (as I tend to do). Wouldn't that restrict the amount of hours I could collect energy if I went with a 2s2p array? I barely get more than 2 peak sun hours in my area, during the winter, based on online calculators.
Nope, 960w of panel is 960w of panel. Potentially you might lose a couple watts while the panels get up to the voltage but it'll be neglidgable overall.
 
Sorry, I guess that statement was a little confusing. I get P=IV and all that regardless on array configuration. Where I was going with that statement was getting the MPPT turned on sooner, and for longer. Maybe it would only gain me 15 minutes of collection, maybe it is an hour? I really have no idea. I was struggling to find much information in that regard. With the winters here, I was just trying to maximize the amount of charge time I can with my small array. I thought a 4s1p would do that. Unfortunately I can not add a 5th panel :(
 
Just pointing out that "low cost" and "Victron" are mutually exclusive. Spending that much money ($~700!!!) for a few watts is losing math.
 
I’m reading some stuff into your questions. But it sounds like you have a ways to go on the design side. Good news is you haven’t bought stuff you can’t use yet. As you probably know, plugging your house in to a generator or battery bank requires a disconnect from the grid. I’d use caution letting a few panels drive your system design. Tail wagging dog. Good group here to help.
 
Plan to build my own 16 cell battery with LiFePO batteries.
Lets say you get 280Ah cells:

280Ah x 16 x 3.2V = 14336Wh

I barely get more than 2 peak sun hours in my area, during the winter,
960W x 2h = 1920Wh

To fully charge your battery from empty:
14336Wh / 1920Wh daily = 7.46 days

To fully charge battery daily : 4 panels x 7.4 = 30 panels

How many Wh per day are you expecting to use?
How many Wh per day will those AIOs use? (more than you think!!!)
 
Samlex EVO 4248sp. You gan run 120 or 240v. 4200 watt.>30w idle.
 
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