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About to go solar but want to be sure we have the appropriate setup - advice needed


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We are about to go solar and have had numerous quotes.  Before confirming one, I need to know that we are getting a setup that will fit our needs:

1 x 8 kVa Sunsync inverter

2 x 5 kWh Sunsync batteries

14 x JA Solar panels 545W

Property: average 55KWh / day (Only one account but cottage has separate Db board)


Main house - lights/plugs/alarm/Wifi/fridge/small freezer/TV

Outbuilding - small fridge / lights / plugs

Cottage - lights / plugs / alarm / Wifi / fridge / TV


Air cons / geysers (put on timers or would be nice to have at last 2 on essentials maybe?) / swimming pool pump (on timer) / 2 x washing machines / 2 x dishwashers / 2 x ovens (stoves - gas)

Will the system quoted do this and how best to setup the system? Can I put things as Aux instead of non-essential?

I am dealing with the quotes as my husband is too busy (and most probably as clueless as I am :)). 

Trying to get my head around all the terminology so would really appreciate some advice, tips etc.

Many thanks.

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Is your current supply single or three phase? What amp rating ?  what is your current peak load etc. Have you done an energy audit on the house and cottage to see what loads they use? or do you have a very good idea of what loads they use?

If you want to maximise your solar usage and reduce your electricity bill put as everything or as much as possible on solar, excluding maybe the ovens?  this way you will maximise the solar usage. And reduce your eskom bill the most. And get the best return on investment. 


Ideally if you can control your load thru Sonoff devices or timers then one can determine when things will run like the pool pump (500 - 1000w?), geysers (convert to 2kw elements), aircons (12000btu typically uses 1200-1400watts), Dishwashers (150-2200 watts when heating water) and front loader washing machines (200-600Watts excluding water heating) typically have a low load, except when heating water, for the washing machines one can typically set them to cold wash.

However, your proposed 8kw unit may not be big enough for this, you may consider going 12kw? if available? or two 8kw units in parallel.

During the day with good sun, you would be able to save using little or no eskom.

However at night or when clouds pass overhead and shade the panels, the 2 batteries may not be able to carry a high load, due Max Discharge Rate, adding more batteries will increase the max discharge rate.

And at night during load shedding you would need to educate all residents to not turn on Aircons, Dishwashers, pool pumps etc. to keep your load low, to get reasonable load shedding / cable theft coverage?

You will probably find that after installing you will want to add more battery capacity, and more panels, for longer run times at night, and to cover the 55kw used as well as to recharge the batteries. So try to plan for this by choosing installation space that will facilitate extra batteries and hopefully your have enough roof / carport space for additional panels.


Other options maybe to have a second solar install for the cottage? rather than 2 x 8kw or one 12kw inverter?

To split the second DB at the cottage, into essential / non essential loads,   one will most likely have to run a new supply cable and put in a second db to be able split the loads at the cottage, or maybe wifi controlled switches in the cottage db which disable circuits that are non essential? During load shedding or cable theft?

Chat to your potential installer and see what they would recommend as well? There are many things to consider.

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Do you want backup for load-shedding or do you want to try and go off the grid as much as possible?

For 55kwh pull a day, you're going to struggle with what they're trying to sell you. We have a near-identical set-up, but with 12xJA 470 panels, our usage is however about 21kwh on a hard day for a family of four. 

Tell hubby that he's going to have to get in on this and learn with you as people don't realise that everyone in the house has to play along to make this work. I have my wife on the app so that she is fully aware of where we stand for the day, this makes her planning things also easier. 

With your usage, I would use timers to smart manage pretty much everything that you can during those sunlight hours. Lights, TV's computers, Fridge should all be good through the night, but I feel that you're maybe going to be a battery short to get you through the night and maybe a few extra panels short during the day to meet that demand.  








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This might help to give you a little perspective. 

My house with a cottage uses 55kw a day in winter. 

The cottage and house are running on the solar system and I bill the cottage every month for electricity via a separate meter. 

My system is:

2 x 5kw SRNE Inverters
4 x 5.5kw Shoto Batteries
24 x 455watt Mono Panels

I like my creature comforts and I consider my aircons an "essential item" 

I have a heat pump for the house on 2 x 150lt geysers in series which is on a timer from 9:00 - 13:30

The cottage is still on a normal geyser but I have fitted a 2kw element to lower the peak draw, which is on a timer from 11:00 - 15:00

The washing machines and dishwashers may only be used between 9:00 - 14:30 in winter......a little earlier and later in summer. 

Then I have a 9000BTU inverter aircon in the kid's room and a 12000 in my room. Which I run as and when I please. The cottage does NOT use any heaters at all. 

Both the house and cottage have standard DEFY stoves and ovens. 

In summer my system generates between 50kw - 60kw a day and around 15kw - 20kw in very cloudy weather. 

In summer the batteries are usually charged by 10:30 in the morning and run on solar the rest of the day. We occasionally tickle the mains supply but on average use less than 50kw of mains power a month in summer. 

In winter with fewer daylight hours we get a max of 45kw per day. The system switches over to mains when the batteries are about 30% in case of load-shedding, which is normally about 2am - 3am. and back to solar around 9:00am. So we use about 300kw of mains a month in winter.  

My biggest issue has always been the peak draw and your 8kw inverter may not carry the house and the cottage. When the two water heaters' time slots overlap that's already 3.5kw. Then the wife cooks on two stove plates while the washing machine and dishwasher are on and that peak limit of 10kw gets in rage rapidly. Enter mom-in-law with the F*cking kettle and we have 15 minutes of quiet time while the inverters reset themselves. 

If you can, rather go for more panels (it's a SOLAR system after all), and more panels are always better, then bill the cottage for electricity supplied by your solar system and speed up your payback time. 

Otherwise, your system is probably only going to be big enough to run your house, and leave the cottage on mains only. 

Edited by LCG
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On 2023/05/19 at 11:38 AM, zabe said:

Property: average 55KWh / day (Only one account but cottage has separate Db board)

That's high. Try to think of ways that you can cut that down. That leaves you more head room with the solar.

The separate DB may be a problem. My cottage (not inhabited at present) has a separate DB, but that includes a geyser. So how do I put the lights on backup but not the geyser? OK... the answer is elsewhere in this thread: Smart switches (placed where there they can't be got at).

Also think how your tenant might react. They can't use the oven? Fine, then they'll get an air fryer. Won't use as much, but it will use more than a non-backed up oven.

Try to analyse where all the power is going at the moment, and then see where you can cut back. Lower temperatures on the geyser thermostats? Shorter showers (uses less hot water, so less water to be heated)? Inefficient incadescent lighting?

Do your appliances have an economy mode? Those work. My dishwasher will do a full load on 9 liters of water and less than 1kWh of electricity. So it takes 3 hours? So what?

Maybe get a Kill-A-Watt. That'll tell you how much is used over a cycle of whatever, and also what the peak usage was.

IMO the proposed solution is light on battery. But it's not my money. You have a lot of PV power. Try to move as many loads as possible into the time slot when you have lots of free power.

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PS. I know. I sound like a power prefect. Well, this is part of the solar journey.

Some of us, when presented with  the word "solar", we hear "free and unlimited". It ain't so, and everybody has to understand that. Especially at night, especially when it's overcast, especially during a shed, (IE most of the time) there are very definite limits, and they have to be respected otherwise the free, unlimited stuff runs out. The pay off is that if everybody gets with the program, you will have all your essentials all of the time, and a largely uninterrupted way of life.

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