Inevitability

Hehe, yes I'm in SA... No litigation danger. But Barry says the ElonSmart is locked at 65 deg max and there's nothing that can be done. He suggested insulating the pipes cos there's potential losses there... Which I will definitely do. For now, I'm quite happy with what I'm seeing... Even on a overcast day today, I got 2.7kWh from the panels, so it will probably take a proper miserable day to get nothing out.

After seeing your comments on Friday, I poked around in the settings and there is a custom grid timer section with custom temp settings, so I set that to 50deg only at 04:00 and 18:00. So far that has worked perfectly through the weekend with no need for a manual grid boost during the day. The max solar temp that the app allows is 65deg ... but I am gonna ask the PowerOptimal guys if they can change that to 70deg ... the original kwikot thermostat goes up to 70, so the OEM is already comfortable with the geyser running at 70deg. Past 3 days have been hazy sunshine , but the system is already doing all I had hoped for :

And here we are, finally installed and heating my geyser 🎉

I must admit that anything "grid-tied" is a bit scary for me. Mostly because I know almost nothing about it, and because what little i have heard includes engaging with eThekwini municipality in some way (... please correct if I'm wrong). So it's a bit like the Boogeyman ... scary dark figure lurking in the shadows of my ignorance that I think will jump out and destroy me. For this reason, i have been trying to avoid the idea of anything grid-tied ... kicking that can down the road until i understand a lot more.

I got a answer back from PowerOptimal (Elon Smart OEM). Barry was super helpful. He took my panel specs and ran it through a calculator they have to match the element to the panels. For my idea of 4x Jinko 590w bifacial in series, he came back with a 97% match for a 4kW element and 96% match for 3kW. Either way it's looking good. I asked him about how they apply and switch the DC to the geyser element. He said that was proprietary info 🙂 He also confirmed there's no MPPT and no AC-to-DC conversions. He said they have done extensive testing. Side note: Elon Smart has already been around for a few years. So here's where I am: - My idea for max-ing the PV input is compatible with the Elon and the geyser element - Out of winter , I will probably end up with excess energy from the 4 panels that I can't use (...problem for another day, and the app will probably tell me exactly how much I am wasting) - The alternative is to start with an inverter from day 1 , and power the geyser now without batteries, with the idea of expanding the solution and adding batteries and PV and eventually power everything in the house. No wasted energy from panels, and no wasted cost of the Elon. After giving this a (very) little thought, I don't think that a 5kW inverter will be enough for the end-state of my house (with that that we run at the same time), and to buy an 8kW or bigger inverter now is just too expensive for me. So my mind is made up... no offence to anyone who doesn't agree. I am gonna start proper price-hunting and will keep updating here as things move forward. Thank you all for reading / commenting / questioning. I really cannot thank you all enough.

My budget determines the limits of my aspirations here, and I'm not sad about that... I am a big fan of doing small steps to get to the eventual goal. I am definitely keeping this idea on the list. Looks like a very neat way to use up all the energy coming out of the panels and will definitely help with lowering the amount of mains power that gets pulled.

Ah yes. I missed that part 🤦🏽‍♂️ Few years back I had a solar tube system... And on the DB board I had a basic timer... Allowing mains power for 1 hour around 5pm and again at 3am. And exactly as you say, it's just allowing mains to be used ... If the water is already hot, no mains power is used.

Been thinking alot about all the info here in the past couple of days, and I have some follow up questions : 1) @Denns does your 450kWh total include the PI2R geyser heating? 2) I already have my stove on gas, so after I do my geyser on solar, I can put aside around R1500 per month for my next step in solar. My aim is to learn all I can about what's needed to make a big dent in the Eskom bill. @Denns if you were to start from scratch to cover 450kWh/month, what specific components you would go for? (Example "Solis 5kW inverter"). And if you have any idea of pricing, that will be bonus info for me. There's so much stuff out there... Maybe I'm being a bit lazy but it feels like there's too many choices. Any info you can share from your experience will help me narrow things down a bit. 3) If I do my own rough maths, I end up with this: Durban sun hours are way less than inland, so let's say I plan to cover 70% of my bill. In Durbs, that will be days with more than 3.5hrs of sunlight. That's OK with me ... 80/20 rule of thumb means I'm probably gonna spend too much money to cover for the other 30% of low-sun days. 450kWh/month is 15kWh per day. So 3.5 sun hours per day works out to 4.3kW of panels needed Let's call that R15k + mounting costs Luxpower 5kW inverter ... R7500 5kWh battery... R10k? Cabling, isolation box, and all the other equipment needed... R7k? That's already over R50k before even labour cost and I'm being optimistic with prices. Now I'm keeping @Yellow Measure point in mind : I want to keep the big picture in mind and I don't wanna buy anything that won't get used later cos I can't afford a mistake like that. So I'm expecting that all the stuff above is almost non-negotiable. But then it leaves me a bit lost ... I don't know how I could use my R1500 per month savings to build towards the 450kWh solution without a) taking on debt (not an option at all), or b) saving up for 3 years before I can do a full installation I know I have much more to learn and figure out, but my basic understanding is telling me there's no simple way to buy "pieces" every 3 or 4 months, for R5k per piece, and those end up stacking together to make the full solution, but all the while I still get some payback from each R5k I spend cos I'm installing each piece as I buy it. Sorry... There's a question somewhere inside all of that spaghetti: How do I go from maths and calculations to a piece-by-piece solution where each piece can pay me back as I go. Obviously I'm not expecting an answer, but hopefully some thoughts and ideas cos I'm out of my depth here.

Ok I realised what I'm missing... The thermostat needs to feedback somehow or the MPPT will keep feeding power into the geyser Scratch all of that... Thermostat and DC switching are both obvious things I didn't even consider

Ok... Brainfart moment... maybe I'm missing something obvious, but could I find a correct-spec MPPT and a "smart something" to handle the app monitoring and timing stuff, and that ends up being a better solution than the Elon?

Elon has a simple app toggle setting... Solar only / Mains only / Morning showers / evening showers / Morning and evening showers Morning showers will use mains from 3am to 5am Evening showers uses mains from 5pm to 7pm There's also a manual tap on the app to use mains on demand

Wow ... thank you so much for the responses. I have no idea (and the Elon manual doesn't say) how it takes DC from the panels and applies it to the geyser element. To be super honest, I didn't think I needed to understand it, since it's being sold like an OEM product. But now that you asked about it, you made me curious to know so I will ask them when I contact them. Chat GPT also doesn't have any definitive answer, just guessing that it's something to do with duty-cycle manipulation. The killawatt is in the ceiling and it's a pain to access, so I only read it twice ... 56kWh after 5-ish days and 91kWh after about 8 days ... There's no easy way of knowing what time the geyser is switching on/off. The kids prefer to shower in the evenings so they can sleep til the last moment in the morning, and the adults prefer to shower in the morning , so there's no room to change patterns there. Thing is , it's winter now and Durbs winters are short, so I don't expect this much electricity into the geyser after September. But I am not trying to make this completely off-grid. Very comfortable to use mains power to top up, but save enough to make it mostly use the solar ... 80/20 rule of thumb. I must admit , this equation : Pdc = Pgeyser x ( Vstring / 230 )² needs more brainpower that I have at this moment 🤣 Cos I have no idea how PV panel voltage varies through a typical day... I will do some Googling and give it some thought to understand... Or just ask ChatGPT later. The important point I do want to learn/understand more about is how much I lose with no MPPT. On the point of the "unapproved panel configuration"... Before I started looking for panels, I did read the Elon Smart manual and what caught my attention was the maximum current and voltage inputs. I definitely read the section with the recommended configurations cos it was super useful. Then I started looking for panels, and didn't notice anything in my solution idea that would count as unapproved. The 4x 590W Jinko stays under 230Vdc and 15A, so I would be sticking withing the Elon Smart spec. But now since you mentioned it, I re-read that part of the manual and I see they specifically mention to contact them regarding bifacial panels. So I will definitely try to do that and see what they say. On this screenshot it shows Voc needs to be under 250V but other parts of the same manual say 230V , so this might be a typo. https://poweroptimal.com/manuals/ Thank you guys so much for the feedback and questions ... I am learning so much more as I think about these questions and try to answer them for myself.

Just for that story alone I'm so happy I joined this forum... And it's only day 3. Thank you for sharing all of that. I know I'm gonna be back to this page to re-read your journey many more times. Quick takeaway for me on the geyser specifically: I see your journey led you to have the geyser running separately to the main system (using the PI2R). This is effectively what the Elon Smart does... Panels -> Elon -> Geyser No inverter, no battery. The one thing that's been keeping me awake at 23:10 is the question... Am I wasting the R15k that took so long to save up, only to learn too late that there's a much better way to do this that everyone else already knows. But your real-life journey proves that this setup can work well without needing a main inverter-battery system. Thank you @Yellow Measure and @Scorp007 and especially @Denns for taking the time to reply to me.

I'm trying to get my geyser onto solar using a no-inverter-no-battery solution (Elon Smart). I posted a thread here : https://powerforum.co.za/topic/34448-kwikot-elon-smart-please-check-my-work/

Hello World! Can someone please check my understanding and my solution: The Elon Smart will allow me to skip any inverter and battery cost and put PV straight into my existing Kwikot geyser. I was saving money for a Geyserwise MWS (which works on the same idea, but a more "proper" solution), but the price went up by 50% in 1 year so now it's waaaaaaay over my budget. Anyway ... Elon Smart allows max input DC Voltage of 230V and max current of 15A. Being in Durbs, winter sunshine is not good, so I want to maximise the panels to get nearest to the Elon's max. So I tried to find panels that get me near to the limit of the Elon, but in all my searching, I see that panels up to 590W have Isc under 15A but then panels above this Watts all have Isc past 15A. So I settled on choosing 4x Jinko Tiger Neo Bifacial 590W. Voc is around 52V and Isc is 14.49A. I have a white roof so the bifacial will do something, but I'm not expecting much... 5 to 10% extra will still be super useful on cloudy days and in winter. This past week, my geyser used around 11 kWh per day for water heating (I plugged the geyser into a Killawatt ... Yes, yes, I'm dodgy like that). Family splits between early morning or evening showers. No money for a proper solar+inverter+battery solution. I didn't post specific prices or link to listings, just in case that breaks any rules , but panels + Elon add up to around R11k. Still need to account for mounting hardware, cabling stuff, and labour. What I am here to ask and learn is : Does all of this look about right? Have I missed something obvious?