Solar for Beginners [ask your questions here]

@DC999 - "From what I read at the time, the inverters perform to a higher efficiency when they heavily ‘loaded’ from the panels. As in they are working hard."

This is incorrect. It seems a self-perpetuating tale based on efficiency curves from ancient inverters from around Jesus' time 😂

There is no point at all undersizing or oversizing an inverter as they now all hit at least 90% efficiency very early on, like 10-20% load typically.

@banie01 - you might as well use a 6kW hybrid inverter, they cost almost nothing more than a 3.6kW inverter. I'm not 100% sure of the impact on this on deemed export if your kwp panels is still way below the size of the inverter, someone else will tell you. But that said, there are no disadvantages getting the higher output inverter and it will give you more room to play with if you want to add a second string more panels, they can even be in a different aspect as the two MPPT input strings are independent.

Get another installer, he is ripping you off. Have a look in the quotes thread for reasonable quotes and try get an installer that others here have used that is reasonable and does a good job.

That link only shows a screenshot. Do you have a link to the website?

Today's solar for dummies question.

Let's say I am buying CALB cells from PWOD. Which I intend to. And I set them up in 4 parallel banks of 16S, for 800AH. Do I need a BMS for each 16S battery, or will the one BMS do all four? If I need multiple, how do I connect it, on the negative paralel cable between each bank of 16 ? And if it's only one needed, which cells get the balance leads.

Grant payment received this morning. Was approved last Friday so pretty quick from seai

Thanks, that's super super helpful, no need for a diagram etc I get the concept from your description. I couldnt understand before how you'd connect. So, it seems you can go to 16S4P on most BMS, whether thats the Seplos linked above or the Daly bms that Will Prowse seems to reccomend as the best cheaper option - just connecting 4 parallel cells and then paralleling them as 16, as opposed to groups of 16 and paralleling them as 4.

Sometimes I love this forum, ask what some may deem as a stupid/n00b question and don't get made fun of, instead someone usually knows the answer!

Daly BMS is pretty crap (been there myself was my first 16S on my very first lithium home built power wall, they have come a long way, but still considered inferior). And afaik can't talk to your inverter natively. Seplos BMS is more solid, but a nightmare to operate, no app, overly complicated settings and options, has a will of its own - not in a good way - and it can't balance cells (this really is a must unless you can either live with getting lower and lower capacity as the cells drift apart or are willing to disassemble your battery a few times per year, top balance the cells and re-assemble). It can natively talk to your inverter though. Is the latter what you need, @ELM327?

You should watch some of the Andreas ("Andy") videos, the off grid garage to get a much better understanding of what several BMS and balancers out there can do.

Personally I would like to use the JK BMS. It is very good, great app, very easy to understand and works perfectly (tested it myself too and can confirm). It also has 2A active balancing built in. Testing that right now on a dodgy 5kWh pre-made battery I picked up cheaply this week, LOL €200, LOL including working Seplos BMS clone. It does not have native SMA protocol comms via its CAN port though, but a few of us in here are looking into that, it's been done before by others to get it to talk to all the major inverters (Solis, Sofar, Deye, Victron, etc.)

Will works a lot with cheap batteries given to him for free or bought for peanuts. I doubt he would stick a Daly on €5k worth of cells.

Seriously, have a look at the off grid garage

Will have a look at that channel too. I have no loyalty to "must use Daly" or anything, just want the best without spending loads. As you saw, I've made the noob mistakes and overpaid already, I dont want to do it again!

What BMS are you using? I'm seeing more and more that the PWOD cells and other sellers of CALB cells with good reputation are including the busbars and the wrapping tape and the other peripheries in the box too when you order. That neey balancer, I must investigate further, you're not the first on here to suggest and or use it

@ELM327 - "Will have a look at that channel too."

You should do. He pretty much tests every BMS / balancer going and he does great experiments with batteries, pretty much all of it relevant for what we do. He also has an inquisitive mind, likes to find out stuff for himself and take measurements to prove or disprove a point. On top of it, he's a nice guy - I'm in the middle of an email conversation with him myself

Doesn't talk to the inverter as is as it doesn't have native SMA protocol.

This will give you a better idea of what's at play and how it can be developed:

This will give a near perfect solution, a total setup for around €200 that has it all. CAN comms with all major inverters, 200A, bluetooth, easy user friendly self explanatory controls and a good app (no need for clumsy cable connections), active balancing. Temp control. Cheap compatible screen if you like. The lot. Seplos go home! 😂

This might be the bit that sends me over the DIY edge 🤣

Though you are still at the mercy of the dev who wrote the "translation" and that he/she didn't forget something but hey that's why we have Guinea pigs on that thread.

It can also just send stuff over BT to a BT proxy or similar https://github.com/fl4p/batmon-ha but if using esphome you already get all sensors anyway.

Keeping a close eye on it and @unkel 's setup, will try to move to a sunsynk this year for proper battery power.

Can you fix anything if your 40kwh pack goes to 0%? 😂