Limpopoboy

There is a big difference between them.  The one is mono crystalline panel and the other a poly crystalline.  Due to the they have different operating voltages and current.

Inverter: I run two houses on my 8 kW Sunsynk and between the two, now that we've shifted loads and reduced consumption where we can we use between 20 and 25 kWh per day, or 600 to 700 kWh per month. Except for days where the geyser, tumble drier and my ancient dishwasher (not referring to myself here, the actual machine) are drawing current at the same time we could even get away with the 5 kW unit. 7.2 kW for you application sounds like plenty, especially if you manage your loads appropriately. 
Battery bank: We have a 14.4 kWh battery bank which is just barely enough to get through the night. We have too many fridges and freezers, our cinema, although reasonably efficient runs well into the night, and we have quite a number of laptops that draw power until everyone is asleep. I can't see how you would run out with the almost 10 kWh battery bank with your usage. We're six people all using electronics till about midnight, so consumption is very high till then.
Solar panels: Lastly, I have 15x 300W solar panels. This is just barely enough for us, but consider again, I am powering two houses, including the geyser (on a timer) for the one house. So your panels should be ok. 
The only concern is what you're going to do on cloudy and rainy days. With thick cloud cover, solar dies almost completely. You can significantly oversize your array to squeeze a bit of power out of the little bit of energy that reaches us when it rains, but it might just be cheaper to add a generator to the system for those days. The last week or so here in Gauteng we used a lot of grid power due to the rain. Looking at our production, I would need to tripple the size of my solar array (at least) if I wanted to be able to get through the last week. However, this wasn't a particularly bad rainy week. So to that end I will be adding another 8 or 9 panels as that is all I can fit on the roof before moving to the other house. After that I'd rather just add a genny for those rainy weeks with load shedding. My two cents.

He said he is totally off grid. @LimpopoboyThe quote you got is good. Axpert type off grid inverters are tried and tested you will be fine with a mecer,  Kodak or growatt. 

I have the 5 kW Sunsynk, it is connected to the grid, I run a 2 kW geyser, 9000 btu aircon, washing machine, tumble dryer, dishwasher, microwave, kettle and all plugs and lights, obviously not all at the same time, summer time I used less than 25 kWh per month, now with shorter days that is increasing.

@Kalahari Meerkat I am in the Northern Transvaal 😁😁😁

@Limpopoboy something like this, found via Google would be ok, ignore the "can accept electric element" that's for the cloud gatherers, you know, Cape Town, for instance, where in winter you can have multiple subsequent cloudy days where daytime temperatures may not even reach 16degC or so, then, if you were grid tied (you probably would be) an electric element has value. But not for you or me, here in the Kalahari the amount of cloudy days are few enough so as to no be an issue.
To give you an idea about the energy to be had here, we had quite a bit of rain and a few cloudy days this summer, worst period was early January where we had 100+mm of rain over 3 days and few more cloudy ones around that period. Our daily energy production from PV is around the 32kWh mark on a normal day, I'd say, in January we produced 896.5kWh for the month, so not quite all normal days, for the 1st 6 days we produced:
1st 29.7kWh
2nd 20.1kWh
3d 11.2kWh
4th 7.9kWh
5th 15.kWh
6th 35.4kWh
now you can imagine what that would do to solar direct water heating as well, but we had enough hot water over that period, cant recall coming short, so that's why we don't have anything but an evacuated tube HW system. Here, we have not gone through a complete winter yet, so ask me again in September/October how its going, but I suspect we'll be ok.
Just FYI compete monthly measured PV production here... I made changes early December thus prior to that numbers are lower than they probably could have been.
October 2020 - 827.1kWh (26.68kWh avg/day)
November 2020 - 885.7kWh (29.5kWh avg/day)
December 2020 - 917.1kWh (29.58kWh avg/day)
January 2021 - 896.5kWh (28.981kWh avg/day)
February 2021 - 859.8kWh (30.7kWh avg/day)
with March so far sitting at 225.9kWh (31+kWh avg/day so far)
since our consumption tops out at around 20kWh/day, we can afford to waste some energy, problem always is that you have to waste the energy at the time you have spare, certainly during daylight hours and mostly skewed to the middle of the day... unless you can rob a battery factory and get away with it :-), maar jy sal 'n groot trok nodig he vir daardie opsie...

Guys, I'm assuming @Limpopoboy is in the eastern Transvaal, as I know the name thus should have more than plenty of sunlight to use for hot water.
We have a 12 tube HWC without electrical element etc. and we have no extra way of heating the water here, so that would be my suggestion for @Limpopoboy the only addition I would suggest is that you consider for the future, I would see how it plays out first without adding a gas run through HWC and if it turns out that in the depths of winter, late at night, the water may be a tad too cold for comfort, then adding a gas driven run through HWC to the mix, just for the odd day, when you need more hot water than solar can provide, may be a consideration, but I'd say, note this option and file it away, just stick with the evacuated tube system initially.
Most evacuated tube solar HWC's don't have electric elements to them, you can usually have that as an option, but I don't suggest it unless you are grid tied.
Basically efficiency wise, heating water direct, vs creating electron flow and back to heat via heating element, the electron flow option with heating element is way less efficient and more costly than heating the water directly.

Solar evacuated tubes. It still has the electric element that is controlled by a Geyserwise or can be switched on manually if there is no sun. 

As I understand it @Limpopoboy won't be grid tied, so to have an electric element in the HWC would be no option, since if the sun don't shine to heat the water by direct radiation, then there won't be enough PV based production either.
I suggest that you will not need the gas in additon to the evacuated tube solar HWC, except in extreme cases, where you may have visitors and more than normal amounts of hot water are consumed.

I agree with Achmat that gas for cooking is the way to go, we also use it, although a lot more than Achmat, more like a 9kg bottle a month,  will be looking on cutting down on that a bit with a induction cooker for cooking whilst the sun is shining and excess energy is to be had, but would not turf gas, the potential battery implications it would have otherwise, make gas a no brainer.
As for HWC, I still suggest the solar option, evacuated glass tubes etc. there is nothing preventing you from putting in line a run through gas heater unit, if the water temperature isn't up to what you expect, but assuming its a tad colder than you'd like and you *have* to use a run through gas heater, at least you won't have to heat up the water from ice cold, yet again saving in the process...

Gas for cooking is just so much better not just from an energy efficiency point. Why do you think restaurants and chefs only cook on gas. I've been cooking on gas for over 15 years now and would never go back to cooking on electricity. If I was building a new house, gas for cooking would be integrated even if i was not going solar. I use one 19kg gas bottle per year for our gas stove and we cook every day.

I am constantly amazed by the appliances that are available these days. New fridges, dishwashers even tumble driers are so much more efficient now due to smarter electronics and better motors.
 

Yes. Unit = kWh 

That does change your situation as you have nothing to work from. 
Peak load would be the point where you draw most power. This would determine the inverter size. You can do this by adding the wattage of all appliances that could be on at the same time. Fridges, freezers and aircons are difficult as it fluctuates. My 12000btu inverter aircon goes from 500w to 1.1kw depending on the room temperature. Dishwasher and tumble dryer also fluctuates depending on where in the cycle it is. This is from personal observation of my appliances. 
You could also use a killawat plug to measure individual appliances like your existing fridge. 
Pool pump is a constant draw so it's easy to calculate. Same for lights, geyser, kettle and microwave. 
Graph of my normal usage with the pool pump running for 3 hours from 12:00, 12000btu inverter aircon running from about 22:00 till 08:00 the next morning, geyser peaks at 06:00 and 17:00, 16kg top loader washing machine doing one load, one load with fish washer, domestic ironing for one hour, hairdryer for 15 minutes, chest freezer, fridge, well point pump as I am off grid with my water so it comes on every time a tap is opened. 
Ended up using 40kWh for this day. 

That's a lot 
The only way is to look at an energy meter to monitor your house over a period of time. Simply adding the wattage and possible runtime of appliances is not going to get you an accurate estimate. 
I have 3 aircons, a pool pump and two pumps for my well point water system feeding my house and I'm using on average 45kWh per day with a mac of 60kwh if I run all 3 aircons for most of the day. 
I started with an efergy monitor to monitor my whole house before I decided on going solar. The next step was to try and bring the consumption down by cooking on gas and an evacuated solar tube geyser system. 
I repeat, don't use the rated power of appliances to try and determine and size a solar or battery system. 
 
Edit 
We a family of 4 and it includes a garden flat I'm renting out to a couple and their teenage daughter. 

Agreed its too much. 
Daily pool would be the daily consumption of the pool pump and cooking AC would probably mean that he is using electricity to cook and not gas

One more thing, am efergy is not installed so you are not tampering with anything. 
It's a clamp that goes around the incoming live wire from the electricity meter and it sends the data wirelessly to the receiving unit. 
You can monitor the whole house or attach the clamp to an individual circut breaker to monitor individual circuts. 

I'm assuming you don't have a monthly value for your usage from a bill or prepaid? A good ballpark would be averaging that per day. Initially when doing my calcs for our system I just took a photo of our prepaid meter every day for a couple of weeks in the morning and evening to get an idea. We're two and average 12-15kwh per day with a lot of AC usage but no pool.