Mini-Powerwall

7S is 24V, not 8S. And 8P still isn't enough, you want a bit more that that, even with 24V. If you plan to use the 300W that is. 15P for reused laptop battery cells.

That inverter seems pretty expensive for a 300W unit, but I'm not familiar with your market. Here in Germany I can buy a decent quality 24V 300W pure sine wave inverter for about 80 EUR. That's about 95 USD. I suggest looking at established companies or brands that belong to a shop, i.e. hardware by some OEM sold under its own label. They usually don't want to sell some shit because it has their name on it. And only buy a unit with a comprehensive documentation/specification that is presented to you up front. If you have to search for basic information -> look for another product.
 
I think I have a good handle on the battery pack and inverter, now what about the solar setup? If my understanding is correct I'll need a BMS unless I'm only charging at 3-4V right? Otherwise I risk damaging the batteries/fire. Wonder what others have used for smaller setups.

Thanks,
-ck
 
There is no direct relation between a BMS and the charging voltage. The BMS can do several things for you, depending on what you want to install, and balance charging can be one of these things. But that is usually something for smaller batteries and so it could also be that charging is under no circumstances handled by the BMS. You solar charge controller will usually charge the battery, hence the name, and the necessary charging voltage is given by configuration of the battery. Ideally it can handle lithium batteries and isn't solely made for lead acid.
 
That's a 20W panel and a cheap PWM controller. Don't expect much. And also, this is made for lead acid and not suitable just so to charge lithium batteries.
 
Personally, I'd buy the PWM charger separate, unless you can find a great deal with mono-crystalline panels.

Being a 20Watt panel, thats not much. Altho, at $70 and getting the pwm charger, it 'might' be worth it. How much is the charger on eBay/Amazon/etc just by itself? That's a really generic charger and can be easily found on eBay/Amazon/etc for low cost. I don't remember their pricing, though.
So, what you do is find the charger elsewhere, subtract that the $70 and then divide that price by 20, and that'll give you the price / watt. Anything below $2/watt is great for Poly panels. For Mono panels you'd want lower than $1/watt. As you can find panels as cheap at $.50/watt in some locations.
Here in Florida there is a warehouse that buys solar panels from other company's that either selling out all their stock due to liquidation, replacing their panels in an upgrade, buying slightly damaged panels (cracked/chipped glass, bubbling, bent frame, etc) that are being replaced, and then sells them to DIY'ers at >$.60/watt, some as low as $.30/watt. But, you buy a pallets worth of panels when you buy them, though. However, I'm sure there are resellers out there who buy those and then mark them up a few nickles worth

Addendum: Totally agree with DarkRaven. I forgot that at first. The charger is for LA's, not LiIon's. So that makes a difference. The panel could charge LiIons, but not very fast. If you wanted to get a combo like this for LiIons, look for MPPT charger, not PWM
 
70USD for 20w panel incl that charger is expensive per W.... Very expensive per W. The PWM charger is not worth that much :)

The charger cost like 10 USD and the panel you get for around 30USD max
All with shipping :)
 
I doubt that this is a real 20A MPPT controller. MPPT technology employs an inductor / a coil and that probably wouldn't fit in this small case. Or maybe it would, I could be wrong, but it doesn't say MPPT anywhere there and just because Amazon shows you this item when searching for MPPT it doesn't mean it actually is one :)
Also a MPPT solar charge controller isn't automatically suitable for lithium cells. I think there are no small and cheap solar charge controllers for lithium cells available at the moment. I'm no expert in that market, but if something like this would exist then people would have found it already and you would see these more often.

I know that EPEver/EPSolar has a lithium controller coming, similar to their Tracer A series in size, power and features. Just for lithium instead of lead acid. It will be something like this in terms of size (and price, hopefully): https://www.banggood.com/Epever-Tra...o-MPPT-Solar-Charge-Controller-p-1089465.html
 
Above link is PWM what I can see? ie the one from ciderking
 
Here's Julian Iletts view on that type of "MPPT" charger:

 
*shrugs* I haven't seen anything on that one yet. Do review search for it and see what you find.
 
Well, at least it claims MPPT and lithium battery compatibility. If it really works and if it is any good...I don't know! I've seen this unit before, maybe you can find some reviews somewhere on the internet.
 
Well, it 'claims' to be an EPEVER. If it truly is, then you got something worth the cost (I'm guessing). I'd go with the larger unit if possible.
 
Ahhh, yes. Looks like it. It would only be able to be used as a charger, though. The output is:
Max. output current: 3.3A 3.3A 4.5A 6.6A
Max. output power: 100W 100W 130W 200W
Output voltage range ( Max. battery voltage+2V)?46V
Tracer****06LPLI: ( Max. battery voltage+2V)?58V
Tracer****10LPLI: ( Max. battery voltage+2V)?80V
Click to expand...

So you could only pull out of it 200w max. So, only a charger unit. Still good for $70
 
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