Hi everyone,

I am very new to solar and need some advice. 

I will try and give as much info as possble and also have a few questions.

We are looking into a solar investment but are unsure about what size system to get. We are essentially looking for a system that can almost or completely take us off the grid. I would like to save as much as possible on my electric bill as well. 

We don't have alot o appliances etc, (or so I think) so my idea is to get a 5kva inverter  with a 10-12kva battery and 8-10 solar pannels so that the system can have enough battery storage to get us off the grid or 90% off the grid. 

Is this even possible with a 5kva? 

Here is a list of electrical devices around the house:

Electric gate motor, double garage motor, 8 channel camara system, alarm system, electric fense system, oven and stove(we are going to go over to gass), pool pump, washing machine, tumble dryer, dishwasher, fridge, freezer, 2 x tv's, wifi, about 400watts of light at night, 400 watt heater in the winter, geaser(wich is going to get converted to solar) hair dryer, microwave, coffee machine, air fryer. 

This is most of what we have, I have calculted that we will probably not use more than 5kva of power at one time, but I might be wrong. 

Can a smaller inverter system with more pannels and bigger batteries work? 

Another question I have is should I get a solar geaser and run it parallel to the solar system or is it better for the geaser to run of the inverter as well?

Any advise will be greatly appreciated.

Regards, 

Oelof

I first started off with a Must 5kva inverter, 9.6kva batteries (Gel) and 1.5kw worth of panels with no grid connection at all. 

The inverter didn't have to worry about half your gear and worked mostly for the loads we put onto it. The problem comes when your not able to control the loads. Ie fridge, freezer kicking in.

With what you are listing i would think you will probably be running into problems. I.e pool pump running for 4 hours, dishwasher requiring 3 hours it becomes very hard to balance your energy load. We had a 50L hot water system that when i turned it on, if the pump was running and the fridge turned on then it would overload the inverter. of course this depends on the appliances as my new 600l fridge draws 1/4 the power of my old 430L fridge did.

You could use this as a starting spot but things like the inverter which you can parallel to increase the power might have gone out of production and you can't parallel units that are not the same, when your ready to upgrade.

If i had that lot of gear and wanted that setup then i would start by making a separate power circuit which is just the solar and start putting the things that run all the time onto that circuit. This would reduce your energy costs and give you a good starting with what you can and can't do with solar off grid. to start with off grid was all about load balancing and having to choose what you required as a higher priority. Also the difference between summer and winter in terms of power is big. 4 less hours of sunlight = more power running things from the batteries required.

Keep a diary for a week and list what is running at what time of the day. I would recommend buying a cheap load meter which you can move from device to device and see what loads they actually do require. See what start up load and running loads each device uses and then work your system based on what you actually have already in use and the way you are currently using them. it might be a pain for a week keeping track of everything but the better you know that the better you can prepare. I.e if you have 1 person running the microwave, 1 person having a shower and 1 person using the hairdrier even if it is for only a few seconds of cross over could be the difference between inverter handling the load vs tripping from overload. Things like the pool pump and dishwasher i would only run during sunlight periods. Overcast or winter days though PV input may not be as high as you would like so the more your running on those days the less recharge is going into the batteries. End of the day it is well worth the $20 to buy the meter and run around for a week seeing what your loads really are and when you doing it all. Better the mathematics going in the better the mathematics will be coming out.

It may just be better for you to spend more money on a bigger solar array and change to using all the power hungry gear during the day when the solar is free power for you and only buying the small loads for overnight. I know a few people who wanted to go off grid and i advised them to go this way instead just to see what completely off grid feels like before they have the expense of batteries and rewiring. For some the found the power bills dropped enough that they no longer cared about going off grid. Others decided working to a sun's up so i can do stuff rule was simply to hard so continue to pay the big bills. 

There is no easy one size fits all so please do the math's. Putting a good PV system on the roof now means you already have panels ready for when you switch to off grid later, so it's not a one way or the other sort of idea.

Going mostly off-grid is not that difficult. Going completely off-grid is more difficult and significantly more expensive as you need to be able to survive 3 or 4 days of overcast weather.

I have a similar system to what you envisage. 4.6 kW inverter, 4kw of panels, 10 kWh of battery. I can't put my hand on the Bible and say that I'm completely and absolutely off-grid, but my lights have been on, fridges running etc for 4 years, and I spend a negligible amount on electricity. Over 4 years, through fair weather and foul, I am averaging 2.4kWh of power a day bought from the grid. 

You need to look at peak load. This might be hard for you to determine right now. But if you could have more than 5kW of demand at any time, then it would be unwise to back up the whole house. On my property the out buildings are not backed up, so when there's a power outage I lose the sub DB in the outbuildings, which means no pool pump, no guest geyser (we run an extension lead to use the washing machine). 

Peak load is important because your inverter is rated for a certain current/power on the backed up circuits. Usually they will tolerate a bit more than the peak for a few seconds. We had to learn that we can't use the microwave, kettle, toaster and dishwasher all at the same time. I think there will always be some amount of controlling loads that has to be done. A way to reduce this is to get an inverter that gives you more headroom - so 8 kW.

I second @Webbie's advice to buy a load meter. If you approach an installer, they will want to know at a minium how much electricity you use on an average day. They will probably recommend that the geyser and stove not be backed up. If you go to a full gas stove you should back that up so that the sparker and fan still work, but they don't use much power.

Remember things like hair dryers. We don't think of them as appliances, but they can draw significant power and may cause trips. Don't overlook irons either.

@Oelof, how much electricity do you use per day on average? That's a good starting point. You should be able to get this from your bills. KWh please, not rands. And preferably a summer and a winter figure.

To add to the completely offgrid topic, I think if 10kwh lithium batteries can get you through a 24 hour cycle then that is the size of the system you need. 

The price of pretrol/diesel to get you through 4-6 days of overcast weather is way less than upgrading the inverter and tripping lithium batteries. 

So a compatible generator should get you through bad weather even cheaper a municipal electricity feed.

On 2023/06/19 at 10:54 AM, Bobster. said:

@Oelof, how much electricity do you use per day on average? That's a good starting point. You should be able to get this from your bills. KWh please, not rands. And preferably a summer and a winter figure.

My apologies for the late reply, its been a hectic week. I am not sure how much we use per day, but I buy about 750 units a month. ( we have prepaid )

Thanks for everyones feedback. 

So I have decided to rather go for a 8kva Sunsynk inverter with a 12.5kva battery and 10 550w solar pannels. 

From what Ive read its much easier get 95% off the grid than completely. My main goal is to be almost off the grid appart from those rainy weeks and to save on my electricity bill as much as possible and be loadshedding free ofcourse. I hope this system will get me close to my goal?   We will also be putting a solar geyser in, which will be apart from the inverter system.  I also want to go over to a gas stove and oven, but I will do this at a later stage when I can afford it... solar is damn expensive!!!🥴

I hope I am on the right track and that its worth it at the end of the day? 

Regards, 

Oelof 

Edited June 21, 20233 yr by Oelof

This system will most certainly get you ‘almost’ off the grid. Just make sure to move ‘workloads’ to the day time so you can use your panels. Also maybe consider a Geyserwise system with a 2kw element and timers for your pool and other lights, Solar geysers have its drawbacks aswell so ensure you do your research -  also consider converting all your lights to Led lights as well. You should be fine. Make sure you monitoring your usage - Solar assistant personally is perfect for my use case. 
Good luck! 

Edited June 21, 20233 yr by Raiden2912

6 minutes ago, Raiden2912 said:

This system will most certainly get you ‘almost’ off the grid. Just make sure to move ‘workloads’ to the day time so you can use your panels. Also maybe consider a Geyserwise system with a 2kw element and timers for your pool and other lights, Solar geysers have its drawbacks aswell so ensure you do your research -  also consider converting all your lights to Led lights as well. You should be fine. Make sure you monitoring your usage - Solar assistant personally is perfect for my use case. 
Good luck! 

Thanks Raiden, just a stupid question... I presume by "workloads" you mean moving things like my poolpump running time, washing etc etc to the daytime? 

Edited June 21, 20233 yr by Oelof

43 minutes ago, Oelof said:

So I have decided to rather go for a 8kva Sunsynk inverter with a 12.5kva battery and 10 550w solar pannels.

That will be a pretty decent size to get you close to off-grid.
Main thing like everyone will mention is load-control.

Try reducing that night time constant lights of 400 watts, try swap out for lower wattage led lamps where possible.

Put your pool-pump/geyser on a timer to run after midday and try doing dishwasher, washing etc also closer to midday.

And try doing bulk of cooking before sunset so you get some sun-assist

Mostly you will be well-off with that proposed system as long as you manage your loads

2 minutes ago, WannabeSolarSparky said:

That will be a pretty decent size to get you close to off-grid.
Main thing like everyone will mention is load-control.

Try reducing that night time constant lights of 400 watts, try swap out for lower wattage led lamps where possible.

Put your pool-pump/geyser on a timer to run after midday and try doing dishwasher, washing etc also closer to midday.

And try doing bulk of cooking before sunset so you get some sun-assist

Mostly you will be well-off with that proposed system as long as you manage your loads

Great, thanks for the advice!

17 minutes ago, Oelof said:

Thanks Raiden, just a stupid question... I presume by "workloads" you mean moving things like my poolpump running time, washing etc etc to the daytime? 

Yes, so having solar forces you to become more power conscious, you will need to move the washing machine, geyser and anything with an element to a time when you can make use of the sun through your panels to run your household. You will start noticing that you monitor usage of your new found freedom very closely. 😁

Geyser, Poolpump, Kettles, Washing machines, tumble dryers, microwave all heavy loads. So consider maybe splitting them into essential and non essential loads. But if I would have a guess you would be fine with the system you proposing without moving these but again each use case is different based on usage 🙏

39 minutes ago, Raiden2912 said:

Yes, so having solar forces you to become more power conscious, you will need to move the washing machine, geyser and anything with an element to a time when you can make use of the sun through your panels to run your household. You will start noticing that you monitor usage of your new found freedom very closely. 😁

Geyser, Poolpump, Kettles, Washing machines, tumble dryers, microwave all heavy loads. So consider maybe splitting them into essential and non essential loads. But if I would have a guess you would be fine with the system you proposing without moving these but again each use case is different based on usage 🙏

With the system you're looking at, if you manage it the way you plan, you might be able to avoid a solar or gas geyser, and maybe even the gas stove or oven. I'd suggest to get used to it for a while, especially heading into summer, and only then decide if you really still need more.

17 minutes ago, GreenFields said:

With the system you're looking at, if you manage it the way you plan, you might be able to avoid a solar or gas geyser, and maybe even the gas stove or oven. I'd suggest to get used to it for a while, especially heading into summer, and only then decide if you really still need more.

Fully agreed. 

58 minutes ago, GreenFields said:

With the system you're looking at, if you manage it the way you plan, you might be able to avoid a solar or gas geyser, and maybe even the gas stove or oven. I'd suggest to get used to it for a while, especially heading into summer, and only then decide if you really still need more.

Thanks. I might first see how the geyser  runs with the system. Would you rather replace the geyser with solar first or go with a gas stove and oven first?  

1 hour ago, GreenFields said:

With the system you're looking at, if you manage it the way you plan, you might be able to avoid a solar or gas geyser, and maybe even the gas stove or oven. I'd suggest to get used to it for a while, especially heading into summer, and only then decide if you really still need more.

This actually got me thinking. Perhaps I should get a geyserwize timer for the geyser to run during daylight hours and then rather invest extra money on a gas oven and stove? 

8 hours ago, Oelof said:

This actually got me thinking. Perhaps I should get a geyserwize timer for the geyser to run during daylight hours and then rather invest extra money on a gas oven and stove? 

Invest in the Timer. I use a heat pump for hot water but it only runs while the sun is up. so the timer turns it on at 08:30 and off at 18:00. I am completely off grid thou so making sure i have sunlight coming in to power things is a lot easier and cheaper than having lots of extra batteries to hold that power. In your case you would set the timer for when the power you buy is at it's cheapest, So here if i was buying power i would have it turning on at 23:00 and off at 04:00 if i was connected to the grid.

Unless your oven is broken i wouldn't be changing it over. Not because i don't like gas, because i do and i have a gas oven, but if your trying to future proof your costs then in the short term you may be better but in the long term with carbon emissions getting more and more attention then the price for the gas will start going up and very quickly i would think. In the short term i will keep using gas but in the long term I'm already planing on what will be needed to have a electric stove in use. If your not off grid then the stove does not need the battery to support it. In short if the oven costs you 1k how much power will that same 1k buy you and then how much cheaper is the gas at today's prices. you may end up using the old oven for 2-3 years before you actually break even on the purchase costs, but will the gas stay the same price for long to keep the ongoing fuel costs a cheaper option?