@mattwilcox That's an oddly sharp rebuke to level at a stranger who asked someone else for help.

What made their request so objectionable, to you?

Let's do this.

@TechConnectify I was gonna make a joke about I hope he explains the refrigeration cycle again but that last 30 minutes was everything I could ask for

Let's do this.

@maruno @TechConnectify I built my own 20kWh + 5kW off grid setup, batteries included, for about 2000 euros.

LFP cells cost about 40-100 per kWh, you just have to add a BMS, inverter and some cables.

The expensive part is people. Same goes for the panels; 5kw of panels is 500€, but getting them put on your roof and cabled and all that costs (sometimes tens of) thousands, because there aren't a lot of people who do it and they want a high profit margin.

Happy to show you how to do it though

@anthropy @maruno @TechConnectify My budget to install 8kWp on my roof in Belgium when I bought the panels in 2023: 4K€ panels, 2K€ supports, screws, cables etc. 1.5K€ inverter and at least 50 hours of my time (not finished yet). Today the panels part could be reduced to 2K, but the energy policy makes injected energy worthless, so I have to account for a battery for when my EV isn't charging.
Panels are cheap but we're often forgetting the other equipment and work needed to install them.

Let's do this.

@aris @maruno @TechConnectify Batteries are also cheap if you know where to source them, same goes for the inverter; 1.5k sounds like a fancy one, I got two offgrid inverters each capable of 6kW+ for less than 500 a piece, and roughly 15-20kWh worth LiFePo4 cells for 800 ish, a BMS for 250.

I'm guessing my situation made them easier to install though, as I'm putting them down flat on my carport with clamps on the sides, my 5kWp took roughly
5-10 hours. It honestly depends on your situation.

@anthropy @maruno @TechConnectify I wanted SMA (5kW dual input single phase) but it was a mistake. Where would you recommend buying batteries in Europe? The prices I found were around 300€/kWh so way more expensive than what you tell me, but I haven't done thorough research yet (I wanted to study my overnight power requirements first)

@aris @maruno @TechConnectify I actually source them straight from China, because they are the king of LiFePo4; in 2012 ish western manufacturers choose to go with nickel-cobalt chemistries, which are far more expensive, because at the time they had a much bigger capacity per weight. These days they're very similar.

To add, China tried to flood the western markets with cheap EVs but got held back by regulations/taxes so they have a huge oversupply of these batteries and sell them for dirt cheap

@aris @maruno @TechConnectify You do have to look around for reputable sellers, because of course the cheapest ones are also cheaply built, but there are very good ones that are also used in cars and such. I'm a bit busy / between things right now but if you look around a little you should be able to find very good *and* affordable ones

@anthropy @maruno @TechConnectify Since I would be buying separate batteries and BMS in that case, that requires research and knowing perfectly what I do. But the price difference seems worth it, I'll delay this until I have to to work on it.
Thanks for sharing your experience.

Let's do this.

@aris @maruno @TechConnectify As long as you have a BMS that is appropriate for the load (overspecced but configurable is okay but make sure to configure it to turn off at the maximum load), it should be fine. It's also worth noting that if you have a low voltage pack (e.g 24V in my case) you have to get really thick cables to carry the amps (48V might be better in that sense).

I'll try see if I can find some good cell manufacturer examples later. For the BMS I personally use Daly.

@aris @maruno @TechConnectify As long as you have a BMS that is appropriate for the load (overspecced but configurable is okay but make sure to configure it to turn off at the maximum load), it should be fine. It's also worth noting that if you have a low voltage pack (e.g 24V in my case) you have to get really thick cables to carry the amps (48V might be better in that sense).

I'll try see if I can find some good cell manufacturer examples later. For the BMS I personally use Daly.

@gudenau @TechConnectify TL:DW?

(I do plan to watch it, but would love to hear what parts stood out most to you.)

@anthropy @aris Do take into account your time and what you are getting into, that it's still not finished is an indicator how much worth it can be.

But also I quite frankly find it a bit dangerous what you are preaching to just get any random stuff from China without approvals. (I guess it wasn't apparent) Consider what risk you are taking and comfortable with.

@TechConnectify

TL;DW

how does the solar panel and battery deterioration affect the calculations? The panels might las 25 years but definitely they don't stay as efficient.

@maruno @aris The LiFePo4 cells they're selling here for 300 are sourced from china for <100, they're the same cells, you just gotta know which ones to get.

My system is working, batteries and all, and sure I could and want to upgrade it further, but that doesn't mean it can't be something relatively easy to deploy.

@anthropy @aris You know very well I am not talking about base materials such as the LiFePo4 here, which the average consumer shouldn't even know. But what it is put in, it's certification and the certification, safety and requirements of the full installation and what you are connecting it to.

You do you, but mains and high voltage DC electricity is not a toy.