If restarting from scratch knowing what you know now, how would you build your system differently?

[windtrader]

For RV.
48v vs 24v (easier to support larger loads and smaller wiring)
LFP rather than lithium Li-ion (far safer and greater useable capacity)

 

[Dzl]

for a ground based system DIY batteries can be a valid choice, however, for an RV not so much.

I don't know, personally I have the opposite impression. I see DIY batteries as possibly more attractive for a vehicle/camper build. Vehicle builds are inherently have more constrains and are space limited, DIY lets you tailor the build to the space available, and choose your components and your design based on the constraints and vehicle specific considerations.

I suppose a lot of it comes down to the specific vehicle, a 5th wheel or class A camper isn't anymore space limited than a small home or cabin, I am more interested in small mobile builds and to me it seems like there are advantages (and disadvantages) to DIY in this context. You have more control over space efficiency and layout as well as more control over component quality. I see pre-built as a totally valid approach as well, especially if you find something that is a good fit for the space you have available.

To be fair, I haven't paid much attention to prebuilt batteries in the last year or two, my perspective may be a bit dated if things have evolved. I think the price gap between DIY and Pre-built has closed somewhat, so that is a factor.

 

[SamDeleted]

Fuses

 

[windtrader]

I don't know, personally I have the opposite impression. I see DIY batteries as possibly more attractive for a vehicle/camper build. Vehicle builds are inherently have more constrains and are space limited, DIY lets you tailor the build to the space available, and choose your components and your design based on the constraints and vehicle specific considerations.

I suppose a lot of it comes down to the specific vehicle, a 5th wheel or class A camper isn't anymore space limited than a small home or cabin, I am more interested in small mobile builds and to me it seems like there are advantages (and disadvantages) to DIY in this context. You have more control over space efficiency and layout as well as more control over component quality. I see pre-built as a totally valid approach as well, especially if you find something that is a good fit for the space you have available.

To be fair, I haven't paid much attention to prebuilt batteries in the last year or two, my perspective may be a bit dated if things have evolved. I think the price gap between DIY and Pre-built has closed somewhat, so that is a factor.

DIY and pre-built prices have grown closer but if proficient DIY still saves money. The greater benefit is as you stated, more flexibility in form factor and capacity and performance.

I have a good friend with a Class C RV and he has very little available space to fit standard car battery style and server rack sizes. I've suggested a custom battery can slip cells here and there where others will not fit. My example is options to buy Grade A, EV spec LFP batteries at retail. I have been toying with removing the start batteries and switching to use the house bank. EV spec batteries have higher current draw rating so it support large, short current draws.

 

[OffGridForGood]

Why?

Lol. I heard you can get the emporia vue and flash it with a better firmware and integrate with home assistant.

I love my iotawatt by the way. But sometimes it makes my head hurt when I glance at it just to see what the house is using and I see 20kw!!!View attachment 160943

Starting out, I hadn't realized that the string voltage for the PV would matter much.
I later realized that my MPP limit of 145vDC would mean only 2S PV strings (for the combination of 440W CS and winter temps) and this would effectively mean larger wire sizes. At the time, there were fewer options, and for my initial set up, with the PV literally on the roof above the room with the Inverters, the cable size didn't matter a lot, since it was short anyway. Fast forward to 2023, with all the close-by south-facing roof areas full, now that wire size has more impact because it will be farther.
Yes I could just add a dedicated higher voltage charge controller, instead of using the new 6048#3 and it's PV inputs, but the comms will be better if I use the MPP inputs.
If the EG4 18PV was available back in early 2021, maybe I would have gone that way, but it wasn't. LOL.
I do like the Iotawatt too, wish I had realized they were going to 'get out of the market' I would have bought a second one for sure. Hope the Smart Guys Australia company ends up selling them, I sure would like a second (and third) unit.

 

[Tomthumb62]

I see DIY batteries as possibly more attractive for a vehicle/camper build. Vehicle builds are inherently have more constrains and are space limited, DIY lets you tailor the build to the space available,

Very valid point!

If one doesn’t want to DIY, then look at the Sunfunkits prebuilt batteries. I think 280Ah 12v in a tight and compact package.

You’ll want to add your own shock absorption though. Which is one reason I bought the Powerurus battery, it’s full of sticky foam. Will Prowse hated this stuff in his tear down video, but it’s decent stuff for road vibrations.

 

[Q-Dog]

What would I do differently? I would not build another Victron system without VRM.

 

[Zwy]

Starting out, I hadn't realized that the string voltage for the PV would matter much.
I later realized that my MPP limit of 145vDC would mean only 2S PV strings (for the combination of 440W CS and winter temps) and this would effectively mean larger wire sizes. At the time, there were fewer options, and for my initial set up, with the PV literally on the roof above the room with the Inverters, the cable size didn't matter a lot, since it was short anyway. Fast forward to 2023, with all the close-by south-facing roof areas full, now that wire size has more impact because it will be farther.
Yes I could just add a dedicated higher voltage charge controller, instead of using the new 6048#3 and it's PV inputs, but the comms will be better if I use the MPP inputs.

What does one really need for comms? If you have EG4 batteries, they do communicate with the EG4 MPPT100-48HV.

I have DIY batteries and the EG4 MPPT100-48HV. It would be nice to see daily PV yield using this SCC but my system is 100% run off solar power and I know what daily usage is for total Kwh so essentially that was the yield if batteries hit 100% daily. I don't see a need for comms unless a person wanted the BMS to communicate with the SCC. I never thought it was important to me.

If the EG4 18PV was available back in early 2021, maybe I would have gone that way, but it wasn't. LOL.
I do like the Iotawatt too, wish I had realized they were going to 'get out of the market' I would have bought a second one for sure. Hope the Smart Guys Australia company ends up selling them, I sure would like a second (and third) unit.

 

[virtual400]

I would have researched the inverter options better and listened to all of the bad experiences that folks had buying cheap ones. Unfortunately I didn’t listen and bought cheap. There are a few good experiences out there but too many people installing them had to spend a lot of hours to get them to work and too many hours keeping them working. My install will probably never be hands off and worry free. I still have ”flickering led lights” and other issues. I spent a lot of money for an ongoing “project” that will always be a project. I’m now trying to decide to spend another $12k to move to Sol-Ark inverters to have more reliability and less maintenance.

 

[OffGridForGood]

Unfortunately I didn’t listen and bought cheap.

What Inverter(s) did you buy?

I still have ”flickering led lights” and other issues.

I have a lot of LED lights in the shop, and the only ones that flicker are the cheapie ones from HD I put in the storage room. LOL.
The commercial grade LED shop lights - from a real electrical whole sale supplier - never flicker, leading me to think it is the lights not the power quality that is at issue. -no real evidence just my gut feeling, and knowing those store room lights were less than half the price of the main lights. (you get what you pay for?).

 

[MajicDiver]

Very new at this, but already several things on my side.

1. 48v, not 24v. Lower cost, higher capability, better expandability, more future-proof. Unless you're a vanlifer and need easy 12v interface, pretty much everyone should go to 48v.
2. Skip the all-in-ones, do individual components. Not convinced the MPPT's are as effective as they could be, and idle current of two AIOs is dumb for my small system.
3. Probably not DIY my batteries from cells and a BMS, pre-built batteries are only slightly more $$/kwh and FAR less hassle.
4. Go bigger. My system will do everything it was spec'd to do and then some, but very little more $$$ would build a system capable of more, and more expandable.

What about you?

If I had it do do over, I wish I had invested time to learn how to work with metal conduit before I started- now that I have my system like I want it I’ll be spending a lot of time/work this fall putting everything in metal and also making it look nice. When I started I knew virtually nothing about metal conduit fittings and how to bend it, only recently applied myself and think I’ve got it now

 

[sparrowhawk]

I installed my current system in 2020 and although it's very modest in size it has been wildly more successful than I had anticipated. What that has taught me is if I had doubled my system size I could gone off grid.

My original intention was to put in a system that would keep the lights on during our frequent power outages while reducing my monthly bill for at least some payback which it has done very well. In the beginning it reduced my bill by one third to one half depending on the time of year.

But I knew I could do better so I recently tightened things up around the house and made some minor life style changes and now my bill has been reduced by one half to three quarters.

Unfortunately everything has pretty much doubled in price so it would now be four times the cost to have twice the system size.

 

[OffGridForGood]

Unfortunately everything has pretty much doubled in price so it would now be four times the cost to have twice the system size.

Are you sure?
I see the cost of PV and Inverters I am using dropping in cost, just the copper wire is more.

 

[sparrowhawk]

Are you sure?
I see the cost of PV and Inverters I am using dropping in cost, just the copper wire is more.

Inverters haven't risen as much and neither have panels but shipping for them has. The cost for raw cells have at least doubled which is what I used. I don't know about server rack batteries since I wasn't looking at the prices of them in 2020. The racking I used and the hardware has doubled and the wiring has more than doubled. So I think it's fair to say that overall everything pretty much doubled.

 

[Farm Boy]

I done a lot of research in the beginning on solar and chosen pretty good equipment as it's working pretty good but I now wish and still may change some things I have learned here on this forum, such as things to comply with code for extra safety / peace of mind / possible insurance claims. So in this area is where I wish I had done differently because now I have more work to do before I'm at ease on the complete system.

 

[OM617YOTA]

Wish I'd planned on active cooling from the beginning. Thought vents and fans would be enough, and most of the year they are, but there's a couple weeks during the hottest part of summer where they aren't. Now I'm trying to implement active cooling in an uninsulated trailer, by hacking a hole in the wall and installing a window AC, and covering the existing vents.

Not going to try and maintain human comfort temps, just keep the inverters and batteries from cooking. 85F or so. Lack of insulation basically means I'm trading power for efficiency, which shouldn't be an issue for a solar power system in full summer sun. The window unit has an eco mode, so it'll turn off entirely when below set temp, and not run the fan while the compressor isn't running. See how this goes, fingers crossed.