Calculating solar requirements

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Terence1983

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Ok 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 often 'touch wood' , I think in the last 2 years we have had load shedding maybe 6-8 times. 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 300kwh per month, some months closer to 200kwh 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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Going solar is a bit of a journey, and the first step is understanding your load, and working out how to reduce it and maintain your lifestyle.

I started mine in 2014, and this is sort of how it has progressed so far:

Evaluated loads and replaced the electric geyser, hob and oven with gas (would have liked a lot to replace the electric geyser with a solar one, but the cost was prohibitive if I wanted to install the PV as well.

At the time replacing all three (around R10K - I shopped around) was half the price of installing a solar geyser (around R18K with rebate). I also did it in such a way that I could change between gas and electric geyser in emergencies.

This alone reduced daily usage by just over half.

Then there was a A++ fridge replacement (R8K). Which reduced daily consumption by around 3 to 5% (this was probably not entirely necessary). LED lights etc etc.

Then I sized my requirements for solar which was a 3kw solar array and inverter which essentially covered all my day time loads for free even in winter (including swimming pool). This was R75k in 2014. It is cheaper now I expect.

Nowadays I am looking into options regarding the gas geyser specifically (which is a bit of a pain) and consumes a lot of gas due to losses so is also expensive to run.

The plasma TV will need replacing at some stage, waiting for Eskom to destroy it so I can claim on that but it is a solid old beast so they are unlikely to even get that right.

If you don't have a load when the sun shines then you need to add batteries to the mix to cover your night time load.

And so the journey continues as technology improves and becomes cheaper...
 
IdlePhaedrus said:
Going solar is a bit of a journey, and the first step is understanding your load, and working out how to reduce it and maintain your lifestyle.

I started mine in 2014, and this is sort of how it has progressed so far:

Evaluated loads and replaced the electric geyser, hob and oven with gas (would have liked a lot to replace the electric geyser with a solar one, but the cost was prohibitive if I wanted to install the PV as well.

At the time replacing all three (around R10K - I shopped around) was half the price of installing a solar geyser (around R18K with rebate). I also did it in such a way that I could change between gas and electric geyser in emergencies.

This alone reduced daily usage by just over half.

Then there was a A++ fridge replacement (R8K). Which reduced daily consumption by around 3 to 5% (this was probably not entirely necessary). LED lights etc etc.

Then I sized my requirements for solar which was a 3kw solar array and inverter which essentially covered all my day time loads for free even in winter (including swimming pool). This was R75k in 2014. It is cheaper now I expect.

Nowadays I am looking into options regarding the gas geyser specifically (which is a bit of a pain) and consumes a lot of gas due to losses so is also expensive to run.

The plasma TV will need replacing at some stage, waiting for Eskom to destroy it so I can claim on that but it is a solid old beast so they are unlikely to even get that right.

If you don't have a load when the sun shines then you need to add batteries to the mix to cover your night time load.

And so the journey continues as technology improves and becomes cheaper...
Click to expand...

Thanks for the reply, yea no one is home during the day so load will be minimal, just the home alarm system. We unplug wifi router and anything else we not using, had 2 routers get hit by lightning so we have learnt our lesson. We only use the geyser when we need it, its a small one and heats up within 45 minutes and stays pretty hot for most of the day in Summer, winter we will have to monitor it. Our peak times are a Sunday when we cook and do washing.
 
i would start with a Grid Tied Inverter first and then once you have some bux saved then add the lithium batteries, just make sure the inverter supports grid tied as well as offgrid mode.
Once your geyser and stove is offgrid you dont really need much power at all, im guessing 3kw maximum at any given time.

nice thing about grid tied is during the day you run what you need to and its free like washing machines, pool pumps etc.
 
Terence1983 said:
Thanks for the reply, yea no one is home during the day so load will be minimal, just the home alarm system. We unplug wifi router and anything else we not using, had 2 routers get hit by lightning so we have learnt our lesson. We only use the geyser when we need it, its a small one and heats up within 45 minutes and stays pretty hot for most of the day in Summer, winter we will have to monitor it. Our peak times are a Sunday when we cook and do washing.
Click to expand...

Then you will need batteries to store the energy you collect from the sun during the day so it can be consumed at night.

There are kits if you want to go semi DIY: https://www.sustainable.co.za/solar-power/solar-power-kits/solar-ready-inverter-battery-backup.html

There are other suppliers. But you will still need to satisfy SANS and NERSA regulatory requirements as they currently stand.

For that you will need a qualified (and good) sparky and a PR Eng to sign off and satisfy both sets of regulatory requirements if you want to do this legally across all municipalities in ZA.
 
IdlePhaedrus said:
Then you will need batteries to store the energy you collect from the sun during the day so it can be consumed at night.

There are kits if you want to go semi DIY: https://www.sustainable.co.za/solar-power/solar-power-kits/solar-ready-inverter-battery-backup.html

There are other suppliers. But you will still need to satisfy SANS and NERSA regulatory requirements as they currently stand.

For that you will need a qualified (and good) sparky and a PR Eng to sign off and satisfy both sets of regulatory requirements if you want to do this legally across all municipalities in ZA.
Click to expand...

Will have a look and a sparky isn't an issue, wife works for an electrical company so I can get her guys to do the installation etc.
 
Also maybe a handy tip is to use appliances with timers (Washing machines, dishwashers) to make full use of daytime PV availability in order to reduce layout cost for batteries in the beginning of your solar journey.
 
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