Yup as expected its a little more complicated than just adding things up. At the highest level any electrical design needs to thing about:
1. Surge Capacity - i.e. that it's capable of keeping up with the very peak of your demand to the millisecond (with some head-room)
2. Longer-term run-rate - that it can keep running consistently and reliably at the power required
3. Energy requirement - that you can deliver
(lots of DIY-ers focus on #3 and completely forget about #1 & #2)
Think of it this way - your is like a river providing a town with water:
1. Is checking that the banks are strong enough so a little surge here or there doesn't cause it all to collapse
2. That the river bed is solid enough that it doesn't all wear away really quickly
3. That you get enough water to satisfy your thirst
(it's a mixed metaphor, but I hope it helps you to envisage it)
Batteries are like building dams in the flow - so you can store stuff for later. Solar panels/generator are like the rain etc etc...
So to answer your question bit by bit:
what the electricity requirements ... would be based on the consumption of the machinery I plan on using
As above, depending on your equipment you will need to know - and should be noted on your equipment in the manual or on the side:
A. single-phase or three phase
B. Peak / surge usage - normally in Amps (sometimes in KW) - this will be lower than the rating on the plug
C. Normal run-rate power - might not be written anywhere, apart from possibly on 'efficiency data-sheets - like the A+/A/B/C labels you see on things. Might need to 'monitor' this to know.
D. How much 'energy' you will be using - Formula for this is: Power (C) x time = Energy*
This one depends on your tariff. Sometimes you will be charged just for kWh - just like a domestic customer. If so, the only thing that matters with your cost is C (above). As MightyQuin said - just multiply Power by time and then by your tariff - e.g. for a 1kW pump running for 8 hours per day on a kwh-only tariff of R1.80/kwh:
1 x 8 x 1.80 = R14.40/day
I would also like to use this estimation to calculate solar and wind power, as well as Battery Bank requirements.
This is where it turns into 'design' rather than maths. There's loads of options and trade-offs and compromises to be made here. Do you need to be 'off-grid' or just wanting to reduce your bill. How reliable do you want the system to be (btw 100% is not an answer here, but 99.999% could be... as we know in SA, the grid isn't 100% reliable!).
Basically though you'll benefit from:
- Solar energy 'reduction' - i.e. using solar to reduce your demand from the grid. Here you should design your solar with minimal 'storage' and batteries -- and basically just look at your minimum 'day-time' load. There's no point putting up much more solar than that minimum load, you might put in a little bit of batteries to help you in load-shedding; but financially speaking it won't help.
- Off grid - solar -you'd normally estimate the amount you use per day and then try to build your batteries to be worth 2-3 days in the low-season; and your solar power will need to be big enough to fill up those batteries. How much bigger will depend on your reliablity requirements.
*As an aside -- what's all "KW/h" nonsense... KW is already time-based... kilowatt = Kilojoules per second; so a kilowatt is already divided by time. It's like saying my car goes 100 kilometers per hour per hour... That's why to work out your energy bill etc you need to MULTIPLY by time to get kilowatt-hours -- i.e. the same as working out the distance the car travelled by multiplying speed by time.
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