Starting over - batteries, etc - 12v? 24v? 48v?

[chrisstratton]

Last time I built a system it was a success, but I would like to do it better w/ a new build.

Last time I bought 2 sets of 4 150ah cells (Battery Evo LiFeP04 - used) and made a 24v system (3,6kwh?) w/ a Growatt 3000 and 1740w of pv panels. I installed a 60amp BMS from China which worked great. My experience suggested that I would like to have more KHW of charge. Last time, I was able to run a 110v 12K heat pump and a 110v fridge for 24/7 in the FLA heat, as long as the bus was buttoned up tight with no people inside. For on-the road, I used a Victron 360w DC to DC charger. I am planning to put the system into a van, as before. . That was 2 years ago. I'm 2 years older, soon pushing 70 and looking to work smarter and not harder.

Going forward, I am likely to have fewer watts of PV panels (it's a long story).

What is the current price and feature point for the following?

1) Which "all in one" to select, the Eg4 3kw?
2) Which battery system? 12, 24, 48v? and which manufacturer. This time, I think I would just like to buy a plug and pray battery, possibly w/ an option to double it, if need be. As I mentioned, the 3.6kwh diy battery was marginal for the A/C purposes. So, perhaps ? 1.5 to 2x that amount? Up to 7kwh? Is that nuts?
3) I am thinking a bigger DC to DC charger?
4) Last time, I used rigid 4 each of 435w 77v PV panels. I am inclined to consider "glue down" flexible panels, and possibly only 3 (need to secure the van, etc)
5) Last time, the hvac and fridge were 110V, which of course requires the inverter to run constantly. Should I seek 12v or ? DC volt units to cut down on inverter usage?

Thanks in advance for your time and experience!

Chris

 

[billvon]

If you are in a vehicle, go 12V. You have half your system done for you at that point. You don't need the DC to DC any more if you are at 12V.

Use LFP batteries. Renogy is a reasonable source.

If you are using flexible panels, I strongly recommend a way to leave an air gap between panel and roof. (Alternatively cool the roof.) Better performance and longer life.

12V appliances are a great option.

 

[chrisstratton]

If you are in a vehicle, go 12V. You have half your system done for you at that point. You don't need the DC to DC any more if you are at 12V.

Use LFP batteries. Renogy is a reasonable source.

If you are using flexible panels, I strongly recommend a way to leave an air gap between panel and roof. (Alternatively cool the roof.) Better performance and longer life.

12V appliances are a great option.

Thank you. Yes - plan to use LiFePO4 batteries. Thanks for info. Right now, Battery Evo is coming in near .27/kwh.

 

[HarryN]

The challenge going into the future will be that not all buyers will want a DIY battery pack.

I know that there are some cost savings possible, but consider if you were not very electrical savvy - would you want to buy a proprietary / home built battery pack built by a random person and no support ?

For me personally, I consider a power system built this way to have a negative value to the van, no matter who builds it.

That is just my personal perception - others of course will have a different opinion.