Hello,

So looking for some good advice to get this right the first time.

I have 2 x 200l 5.5kwh Geysers set up in what looks like series, but im not 100% convinced.

I use approx 800 units on prepaid Eskom direct per month. winter this runs to 1100 odd. i guess the geysers are warming up more often.

I would like to be able to have lights and some plugs on during the evening load shedding for up to 8 hours. 

Ideally I would like to use the sun to warm the water through and inverter. however, It seems this could be tricky as i only have funds for what looks like a 5kw system.

 

Is better to go retrofit solar geysers, and a small battery back up with a couple panels or whats the best call here. 

 

any Idea on the unit savings form a small 5kwh syetem with 5, 450w panels? is this enough to warm the hot water.

 

Ideally I would like to make 1 right decision now and be sustainable over the next 7 to 10 years

 

 

Hello,

So looking for some good advice to get this right the first time.

I have 2 x 200l 5.5kwh Geysers set up in what looks like series, but im not 100% convinced.

I use approx 800 units on prepaid Eskom direct per month. winter this runs to 1100 odd. i guess the geysers are warming up more often.

I would like to be able to have lights and some plugs on during the evening load shedding for up to 8 hours. 

Ideally I would like to use the sun to warm the water through and inverter. however, It seems this could be tricky as i only have funds for what looks like a 5kw system.

 

Is better to go retrofit solar geysers, and a small battery back up with a couple panels or whats the best call here. 

 

any Idea on the unit savings form a small 5kwh syetem with 5, 450w panels? is this enough to warm the hot water.

 

Ideally I would like to make 1 right decision now and be sustainable over the next 7 to 10 years

 

I will always be in favour of using panels for power and use some of it to power the geyser. One can use panels to heat water as a loose standing system but once the water is hot all the rest of the PV is wasted. 

Let's add some figures to your situation. 

You are using 26kWh per day(800 / month). 

Panels as suggested can only deliver 11.25kWh per day on average year round. 

To heat 400L of water by 20 degrees would need 9.5kWh per day. Thus 1.75kWh left to charge batteries/other consumption. This if 100% of PV is used. Normally about 25-30% goes wasted. 

To power 350W of loads for 8hrs you need 2.8kWh which you won't have. This is a very low for the most essential like fridge/TV/wifi in the 8hr period. 

At the core I will look at an end state and put in a scalable inverter where you can add a 2nd one later. Also one needs to start with inverter and PV as PV is where one gets the saving from as well as convenience when there is sun and the grid is off. 

I hope this is a starting point for other views by members. 

@RegularDad I'm excited to report that heating your geyser using PV is life changing. I have now turned into a self annointed preacher on this topic. I have a 5kw Luxpower SNA and around 4kw panels. A timer is installed at the geyser, a change over switch at inverter with a 2nd timer to toggle the geyser in and out of the inverter/PV. Geyser element has been changed to 3kw so it doesn't strain the inverter with the odd 0,5kw base loads. Geyser is heated from 11h00 to 15h00 or 16h00 depending on weather. Some battery is drawn as I get about 3,3kw from the panels (not sure why but I guess it's due to losses in the system). The geyser can be switched on on early morning or on demand to use Eskom which is seldom needed. I now average between 5 and 9kw electricity usage per day from 25kw. That's huge in my books. I do intent to invest the saving to buy another inverter so I don't strain the current one, and maybe later a 2nd battery could be bought from the electricity savings. You just need to manage loads when the geyser is on because if microwave is turned on, then the inverter won't be too happy. Your electrician should be able to pull this off as mine did. You have 2 geysers so your configuration may be different to mine, but once resolved, you will be happy. I know I am.

@RegularDad I think @Scorp007 has laid out your issues well, which comes down to moderately high usage, not enough capacity in your planned system to cater for that demand, and a need to start small with scalability in mind.

I think your ideal buy-once system would have been approx an 8kW Sunsynk hybrid with 7kW to 8kW of panels, and 10-15kWh of batteries.

But to start small, I think your best bet would be to read up the reviews on a 6kW Solis hybrid and try to stretch the budget to get one. Along with that, I'd suggest to try getting some of the specials currently around on 550W Longi or Jinko panels instead of 450W panels, and try to push for a 6th panel on MPPT1. As @Unity pointed out, if you've got a 3W element on the two geysers, you could consider running them mainly off solar during the day one after the other on a timer. One 1C battery like a Hubble to start out with (battery compatibility to be checked, no idea what batteries are supported by Solis). That should be okay as a starter system, to reduce but not eliminate your Eskom bill and see you through loadshedding, but not make you off-grid.

You can then later decide if you want to double up panels on the 2nd MPPT and get extra batteries. Before upgrading, though, I'd suggest investigating ways to reduce your consumption, like cooking on gas, or heat pump water heating.

@GreenFields made a very good point.

Before upgrading, though, I'd suggest investigating ways to reduce your consumption, like cooking on gas, or heat pump water heating.

5 years ago I used 1200 kWh a month. Now my total consumption per month has come down to about 350 kWh per month in the same property. Grid use has come down to less than 100 kWh per month. My laser printer is no longer on 24/7 as well as my desktop PC. Their use was quite high but was only found out when I measured their power wastage. Desktop was unused at times for 2 months. My heat pump used to be on for 24/7 and now only about 2.5 hrs a day. 

Each person can check their own load profile and decide where to introduce savings. Not easy to provide guidelines.