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Hi everyone,

Been in sustainable living/off grid etc for ages. Implemented a few sustainable living things into my daily life and looking to go more into it.

So im thinking of going semi off grid to fully off grid, obviously over time due to costs involved. This is more for self sufficiency than Eskom being useless because to be honest for some reason we don't get load shedding that often 'touch wood' , I think in the last 2 years we have had load shedding maybe 6-8 times max that I can recall, besides maintenance outages and once we had no power for 2 days due to a cable issue. We don't fall under city power which probably helps and we stay next to an industrial area (not sure if that is part of the reason, I don't complain)

Its just me and the wife in a small 2 bedroom house. We on average use less than 300kw/h per month, some months closer to 200kw/h and we are looking at going gas for cooking, maybe a solar oven or just braai a lot. We meal prep in bulk also so that helps with not using the stove/oven often, washing is done once a week and in general we are looking at ways to reduce electricity and water consumption in general.

So in terms of solar power and storage, what kind of solar panel setup and battery bank size should I be looking at overall, I know running a microwave, washing machine etc will require a larger amount of power to run so id need something sufficient for that but for now we can use grid power for that until we have enough storage and solar to run that also.

Any advice or guidance on where I can get this kind of info would be appreciated.

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You are using almost no power at all :)

Solar is a "way of life" change in my opinion.

In short (many more details behind the scenes)

1. The bulk of your demand should be shifted to daytime when you have sunlight to supply the power. It also don't mean that you can start each and every appliance you own at the same time during that time.

2. How much power do you need to get from sunset to sunrise? This is what you should base your battery bank on (in my opinion) so that you don't run out of power halfway through the night. Also the bigger your battery bank is the better your system can handle inrush/spikes.

3. As mentioned in 2, how much power do you need from sunrise to sunset, basically to run whatever power you need as well as to have a bit extra to re-charge your batteries.

 

I bought the solar panels first without knowing anything based on my crooked calculation, in the end it actually worked to my advantage.

Since then I learned a bunch for someone with 0 experience in electricity.

Luckily in my household the only thing that did draw a lot of power during night time was a geyser, an oven and a kettle.

The oven is on-grid (used 3-4 times a week), the kettle was swopped with a gas kettle, I do currently use a 900ml kettle for those quick cups in the evening. I sorted out the geyser and manage the timing on the geyser/s.

The swimming pool run from 9am to 1pm (1kwh) (ironing happens between 1pm and 2pm), the wife run the washing machine between 8am and 9am (barely 1kwh) and any other time the geyser/s are not running, the geyser/s run on and off between 8:45am to 14:15pm (2kwh each). But my setup can handle all of that, even the once a week lawnmower. You will definitely not need such a huge system as I can imagine that you already have a solar geyser in place as well.

We have thus far not have dirty clothes nor cold water, knocking on wood :) . I have the grid as back-up currently and only on cloudy days along with load-shedding do we need to manually switch off the geysers to lower load so that the batteries don't get drained. When there are no load-shedding the system run on it's own and will switch to grid if need to.

 

 

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Thanks Wilfred for the reply. wow sounds like you have a decent system.

From the little bit of research ive done,  I will definitely start with a decent inverter that can do grid tied and off grid for later on when we have the battery back up for it. Once we have the inverter I will do the solar panels, once we have enough to run the household from sunrise to sunset I will then start building up a bank of batteries for overnight, overnight all that will be in use is the alarm system and the geyser for  45 min to a hour max early morning which shouldn't use a lot, its a small 150l geyser, I think its an energy saver one, was replaced late last year after the old one burst.

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The trick with the geyser is the size of the element. If it is only you and your wife, you can connect it to a timer (geyserwise). Depending on when you use the hot water, you can actually run that geyser only in daytime.

I added a geyser to get away from night time water heating. My three kids shower or bath in the afternoon and me and the wife take the morning shift. Both geysers will typically be 60 degrees when the sun go down, one geyser feed hot water to the other, in the morning the one geyser will be in the 40's and the one feeding the house will be in the 50's, then the heating cycle start again.

Only when in your case you use the hot water in the afternoon and you really need it in the morning is when you need to heat it during night time, other than that, just heat it during daytime with excess power. 

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Hi @Tbird, firstly welcome to the forum.

There are a few choices with Geyser/Water Heating:

  • Switch to Solar Geyser with a GeyserWise and some Evacuated Tubes - First Prize; Pros - Almost free; Almost never have no hot water; Cons - Costly to initially set up (R22k or less in your case); Has a electricity backup and usage when multiple days of no sun.
  • Change to Gas Geyser - Second Prize; Pros, you only spend what you use; On demand heat, faster than geyser; Cons - Setup can still be pricey and gas is not free;
  • Heat Exchanger - I am not 100% familiar with this tech, but it still needs electricity (however obtained)
  • Try use Solar Electricity to heat Geyser Element - Least Practical, but doable sometimes

I chose the 1st option, and have a manual switch to turn geyser on when needed. I use that switch possibly 3 times a year.

When it comes to Electrical Power - The options are huge and varied (genuinely going from cheapie/manual solutions for under R10k to nearly R200k for your estimated usage). It is really going to depend on what lifestyle changes you want to make, how much you are prepared to invest to go "off-grid" and your long-term solutions. You really need to get an expert into your home to advise you, but you are welcome to tell us their solutions here so that we can try tweak the solution or help you reduce certain consumptions down.

There are cheap ways of going solar, and there are expensive ways. Every single option has pros and cons. Water Heating should almost ALWAYS be the first thing to remove from your electricity, it has the most advantages. Solar Electricity is still not yet as cheap as Municipal power, and wont be for a few years yet, so we all have had to adapt to our own needs.

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Whoops - Missed the approximate sizing question (although this does go back to Wilfreds response about lifestyle change, and my response about huge and varied). PS: Still recommend you get and installer to accurately assess and/or a local power forum user to double check

Your usage is just a bit over mine, so describing my sizing may help (I am broke and my credit card is only in debt due to the solar stuff I have bought!):

  • FAIL - I started with basic deep cycle 100Ah batteries - Calcium/Calcium, but while these are suitable for lake/dam boats and basic caravanning, these are not suitable for solar - Many deep cycle batteries are not suited for solar, no matter what the salesman says. You need proper batteries for solar use, or if using VERY minimal cycles (On/Off) then good quality deep cycle batteries (don't EVER buy the cheapest "Deep Cycle" batteries advertised). Most Solar use needs either high quality Lead Acid batteries (Trojans are good) with higher maintenance, Gel type batteries (similar to lead acid but the water doesn't disappear as easily), Lithium batteries (like the Pylontech), but these cost big money and need to be checked if your invertor can provide the correct values, lastly the Nickel-Iron (don't know of anyone in this country able to afford) which are the gold standard but so expensive that you would need to sell your house just to be able to power your house. My Calcium/Calcium batteries actually melted (and could've destroyed my house).
  • CURRENT - I currently use 200Ah Gel Lead (AKA Lead Crystal like in UPS's and in a home alarm/gate control) - They aren't perfect but affordable. Batteries will almost always be the most expensive part of your installation in the long term, so I always will recommend getting the best you can.
  • PART FAIL - I purchased an Axpert 5kVA Unit - This is a pretty decent unit for either completely off-grid or part-time off grid unit, but it does have some failings when using it as a day-to-day unit. The Axpert acts almost like a very complex UPS, and cannot share certain power sources to reduce usage. It is known as a Hybrid system. It is designed ONLY to charge batteries, and when connected to municipal that means that your solar panels are not much use most of the time (your batteries will be charged just waiting for a power failure). It can switch over at preset times (eg: use batteries at night and charge during day, but it is a almost manual configuration). Understand as well when someone speaks of Invertor, they are generaly referring to something that does everything all-in-one, but in truth an invertor is only one stage of a complicated product. An invertor only converts the DC voltage of your batteries to an AC Voltage that you use for stuff in your home.
  • CURRENT - Due to absolutely no budget, I purchased an Imeon 3.6 "on-Grid" system second hand - The system itself has been amazing, but I had to use my own knowledge and experience to program it correctly. I cannot honestly recommend a beginner go this route as there is almost no support or just costly support. There are many on-grid systems available, but an on-grid system (even if you don't send power back to the municipality), is the right way to go (if you have municipal power and want to rely on it sometimes). If you are prepared to completely switch off your municipal power forever, then look at Axpert or Victron - budget dependant
  • 6 x 280W solar panels - This was actually a decent size for what I needed, but the above equipment needed more. Battled to find similar panels for a long time with the same Voltages and stuff, so try get all your needed panels at once. ARTSolar locally is most economical, but they only keep their sizing for a year or 2. Mixing and matching old panels is very difficult since almost no-one keeps old stock. When you do have to match different panels it can be a big challenge in regards to voltages and currents.

DON'T GET DISCOURAGED by all my comments above, there are a million reasons why you should. I am just explaining that it is not a small change you are making to your life, and I have seen a few take the leap and either get horribly discouraged or worse into debt). Take it all in small pieces and we can help, or if you are hugely rich then do it all once (PS Don't forget then to donate to our forum :))

 

Edited by KLEVA
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Thanks for the advice, yea I plan to do this in stages as and when funds become available. We do not plan on making debt to be able to afford it now. Even if this takes a few years of research and saving, then so be it. Not rushing into anything, will do as much research as possible before we make any decisions.

Our geyser is on for around 50 minutes per day max, I manually switch it on at around 4.30 or so, the wife gets up this time for gym anyway so it works for us. I get up at 5.20 and by then the water is more than hot enough and generally stays hot the whole day.

I do plan to get a kill a watt device to measure usages and see where we can first of all try cut down a bit on electricity usage and then once we get that right we can start  calculating exactly what sort of solution will work for us.

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