June 29, 20224 yr Hi guys, I truly hope this is the right section for this... We currently run a generator where i stay. It's quite pricey monthly to keep running, let alone the noise (which is in a soundproof box)... but still, running cost is heavy. The idea is just to pull us through load shedding. We work from home (myself being IT consultant), wife being a home baker We have (all that needs to be powered): 4x freezers (bosch A++). It stipulates: 245 kWh per year? 1x Samsung Fridge/freezer: 272kWh per year? 2x 65" Samsung Tv's 1x Bosch Oven . stipulates connection rating of 3,600 W ? 4x deco X60 access points across the house 1x router 1x NAS 2x printers 1x geyser Side note: Our stove is gas I live in a complex and my genie just made the "allowed" noise levels/size, so i'll keep it in my courtyard as backup... it is unfortunate we are unable to install solar at this point in time (discussions udnerway with trustees... we'll get there). What do i need to install to keep the above going for my wife who needs her fridges / oven at the least during load shedding... and obviously all our equipment. idea is to just let the lithium ion batteries charge where there is electricity from eskom... and when theres load shedding, live off the charged batteries. Can anyone make any recommendations what would see us through?
June 29, 20224 yr What is your peak usage? so e.g. if the TVs + fridges + lights are on what is your consumption? That will aid in the system specs
June 29, 20224 yr Author Fridges/Freezers are on 24/7 (let's say 200watts per fridge) Lights can be managed, but minimum kitchen & office (14watt per x6.. i.e 3 in my office 3 in kitchen) Oven is the https://www.bosch-home.com/za/products-list/cookingandbaking/cookersandovens/builtinoven/HBG676ES6#/Tabs=section-highlights/Togglebox=manuals/ (the website states: "Energy efficiency class: A+, Energy consumption (conventional): 0.87 kWh, Energy consumption (forced convection): 0.69 kW" I am not sure how to work that out though 😕 Router / Deco AP's / NAS / LAptops etc. I wouldn't say more than 500 watts total Tv's... it's usually on for the wife during the day, and we watch at night (article states: 265Watts per hour?) does the above make sense?
June 29, 20224 yr Author I'd rather have a bit too much to be on the safe side than just too little 🙂 Also, would want the option to extend/upgrade/add if possible down the road
June 29, 20224 yr On face value / opinion , I would select an 8kw inverter . 5Kw is a gamble. That's the easy part. The size of battery bank is crucial . I take it that the 3.6kw oven is a valuable business asset and that will dictate your storage needs . What would be the maximum aggregate period that the oven needs to operate , say we have a outage of 4 hours ? If this is difficult to gauge , I would say that you may need the help of a energy logger to obtain peak energy demand / profile . Edited June 29, 20224 yr by BritishRacingGreen Correction
June 29, 20224 yr Author 20 minutes ago, BritishRacingGreen said: On face value / opinion , I would select an 8kw inverter . 5Kw is a gamble. That's the easy part. The size of battery bank is crucial . I take it that the 3.6kw oven is a valuable business asset and that will dictate your storage needs . What would be the maximum aggregate period that the oven needs to operate , say we have a outage of 4 hours ? If this is difficult to gauge , I would say that you may need the help of a energy logger to obtain peak energy demand / profile . I’d say for the full duration of the outage. As mentioned… I’d rather have sufficient than too little for her business needs.
June 29, 20224 yr As @BritishRacingGreen says, the 8 kW inverter is the way to go for such loads. The geyser can be put on non essential loads, but everything else can be on essential loads. Pair that with at least 2x Hubble AM-2 5.5 kW batteries, and you should be fine. If the batteries don't make 4 hours due to heavy load, the generator could assist for a short while, or get more batteries. Enjoy all the decisions, and financial outlay, but once installed you won't be sorry. 😄👍
June 29, 20224 yr Author Thank you all! ok, I'll get some quotes from people Does anyone have any good contacts/connections for this?
June 29, 20224 yr 34 minutes ago, Johndoe1983 said: Does anyone have any good contacts/connections for this? Depends where you are situated? Cape Town, KZN, JHB, ....
June 29, 20224 yr Author 3 minutes ago, TimCam said: Depends where you are situated? Cape Town, KZN, JHB, .... Jhb
June 29, 20224 yr On this forum, you could give a shout out to @Leshen or @Steve87, as they are well known installers in your area, and professional. They can assist from start to end in all decisions, warranty and maintenance.
June 29, 20224 yr The idea of essentials & non essentials is great & being able to push to the non-essentials during with the grid present is great. However, I have some clients in the Northcliff environs that have been without electricity since Saturday. We all know the crisis, it's a mix of cable theft & that happened twice after City Power replaced it. So my thoughts are at a large capacity inverter like 8kW or 10kW & the use of the CBI astute breakers so that you decide when a geyser is essential or non essential. Imagine having the Geyser or oven on the wrong side of your electricity supply & an extensive outage. At least this way you have control. A geyser can be in the region of 3.5kW & the oven at 3.5kW. that leaves a very narrow power band. So for me it's nothing less than an OG10.0 & 2 X 5.1kWh of Lithium batteries as a minimum. I'm sorry to say Grid outages are becoming more common here in Jozi. It's really a hard situation but I know id want the option to choose what's on the non essential side & power it without rewiring.
June 29, 20224 yr I agree with you Steve, we have been off for 7 days (Full week) in the passed, that is why I have wired my SunSynk 8.8 kW machine as everything essential (UPS). If I want the geyser off, I can drop the breaker. The system can pass through up to 12 Kw without damage, and I personally have seen just over 10 kW passing through to essential (UPS) side, on my machine. It appears the grid and generation capacity is deteriorating at an alarming rate now-days. 🤔
June 30, 20224 yr Since you won't have solar panels, you have to recharge from grid. That's OK, BUT a thing that gets overlooked a lot is how long it will take to recharge your system. Don't ask me! Me just owner, not an expert. But ask whoever does your installation about this. You need to know that your system will fully recharge between load sheds. Ideally the recharging should happen automatically, rather than you having to intervene. I'm sure that all of this is achievable, but maybe not with all the gear that is currently on the market. So ask those questions, tick those boxes. I'm making these points because yesterday I was reading about small inverter + battery systems, and some owners have been caught out lately because some models can't recharge in-between load sheds and eventually can't supply any backup power. What you're contemplating is the same principle, just bigger in scale. Oh... it's not enough for whoever it is to say that it's a C1 battery and you can charge it in an hour. I've recently changed battery brands, both manufacturers will tell you that the package is C1 BUT 1) In both cases the BMS has an absolute maximum charge current limit of 125A. You can't charge a 200a/h battery in an hour if you are limited to 125A. So whilst the CELLS might be C1, the total package isn't. 2) My inverter can only charge at 100A. So in both cases the C1 rating doesn't represent something I can actually achieve or that the battery manufacturers have allowed.
July 1, 20224 yr Author Thanks for all your help guys. Really appreciate it! just a quick one. i wanted to know if I can just install a inverter with some lithium ion batteries in her working room for her fridges / microwave + power the 2 rooms which are opposite the walls. in other words, can I install the inverter in her office and feed power from the grid to charge the batteries directly from a wall socket? Or does it require to be installed with specific wiring right next to the db board (which is elsewhere in the house)
July 1, 20224 yr 5 minutes ago, Johndoe1983 said: other words, can I install the inverter in her office and feed power from the grid to charge the batteries directly from a wall socket? Or does it require to be installed with specific wiring right next to the db board (which is elsewhere in the house) The main DB has all the circuits that originate from the main DB or sub DB if installed. Basically where ever the breaker Is for those circuits for the kitchen is the place to house such inverter. The most elegant way to install is via a sub DB with those circuits removed and a physical breaker for the AC input for the inverter. A plug point feeding the AC input can cause all sorts of overload issues. Remember, when the inverter is in bypass mode the entire maximum wattage plus more will go into that wall socket. The wall socket plug breaker will usually have a amp limit of 10A or 20A on the Main DB. That breaker will therefore trip in the above case. A 5kW inverter has a pass through of +-22A & in bypass even more. Most off grid inverters of 5kW will recommend at least 40A or 50A for this very reason. The plug point will also only have 2.5mm AC cable at best. This cable was not designed to conduct & sustain more than the 20 odd amps for a prolonged period. Usually I would use at least 6mm AC cable for this purpose. So it's best to get it done properly the first time & add an EL to the output loads/ circuits.
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