I came across this a few days back. 

And looked at the concept HERE!

I would like some opinions on this as i am not sold on the idea. Why buy panels just for your geyser, what happens to that power after the geyser reaches temperature. I believe it could have been used for some other loads. 

 

3 hours ago, Jaco de Jongh said:

Why buy panels just for your geyser, what happens to that power after the geyser reaches temperature. I believe it could have been used for some other loads. 

Exactly. It looks like they assume all solarpower will be used by the geyser and if that's not enough the grid will supply the rest.

GeyserWise has a PV geyser system availabe for a while now.
https://www.geyserwise.com/products/pv-water-heating-systems/150l-pv-water-heating-system/

If you compare this to a normal PV system where you want to run your electrical stuff on solar, then I would react with the same response. 

But the idea here is that you don't use a thermal solar geyser to heat your water. So think of those PV panels replacing the thermal panels (Flat of vacuum tube, etc.)
The benefit here is that you can upgrade an existing geyser system to solar with much less cost and with more safety.

• Safety - A normal thermal system can overheat or even freeze. These systems recycle warm water into the panels when they get too cold. If they get to hot the system can blow up (not sure how they handle that these days). With the PV panels this is not much of an issue. It is an electrical switch to limit the heat and PV panels dont have that same issue when water freeze as there are no water in them, thus they handle cold better.
• Installation - You can use you existing geyser installation. No extra plumbing needed. Just an sparky that fits the solar panels, MPPT and new heating element to the geyser. This about half the installation cost for an upgrade to solar geyser vs thermal.

 

In interest is that there is a youtube video on the early "beta" version of the GeyserWise PV system. In this version they charge your battery after the geyser has reached it's temperature. But it does not seem that this has made it into the production version. 

Here is the old Geyserwise video. Battery charging and advantages after 2:45

https://www.youtube.com/watch?v=wd5HRhBc3gI

 

On 2020/05/28 at 9:08 AM, Jaco de Jongh said:

I would like some opinions on this as i am not sold on the idea. Why buy panels just for your geyser, what happens to that power after the geyser reaches temperature. I believe it could have been used for some other loads. 

I agree (but I am biased against any claims of PV gives "free" electricity or saves "huge" amounts of money...)

I ramble too much so will try and keep it short.

Looking at the case studies on the Elon Range web site I get the idea that an average 2/3 saving on energy required to heat water is what one should expect as a win (case study 2).

I their case study for a 2 person family (targetting retirees?) in a one month period the energy required by the geyser was 180kWh. Over the past month my 2 person family's 3kW geyser required around 78kWh for water heating.... To my understanding I will be advised to use 3 x Solar modules in the 295-355W range for the greatest efficiency when using the Elon system to power my 3kW geyser element. 3 x 335W panels at R2450 (?) = R7350 (mounting structure, wire, disconnects, etc, installation and Elon Unit excluded). While moving house I misplaced my crystal ball but if we assume eskom gets an 8.5% increase every year, I start at a rate of R2.25 per kWh and assume an average 85kWh heating requirement I get the following (table shows just the theoretical 2/3 Elon based saving compared to using only grid power - intitial capital outlay is not included)

So under close to ideal circumstances just the panels will have been paid for after about 3.5 years. When adding all the other costs, a world with clouds and the requirement to sometimes use water from the geyser after sunset, for our use profile it seems very unlikely that we will get to the "pay back in 2.5-5 years" mentioned in the FAQ section. While they also make mention of PV units lasting 30 years (?) the Elon unit self only has a 2 year warranty... 

For maximum geyser heating related saving while keeping outlay on PV panels to a minimum the Elon system is probably mostly suited to users who have: a) abundant sunshine almost all days , b) will be able to use warm water from the geyser only in the mornings.

So while it looks like at some stage I could end up saving some money with an Elon setup I suspect PV Panels and inverter that power other loads and possibly dump excess power to the geyser somewhere around mid-day might give more bang for the buck (why buy a bakkie and use it only to drive to town?).

The install manual indicates a max thermostat setting of 55 degree and the user manual indicates 60 while also advising that you should let the geyser get to 60 at least once a week  which might require using the grid if weather is crappy - so total off-grid use is also questionable? The Elon 100 system savings/requirement calculations also work on a 6 minute 40 degree shower with a low-flow shower head....... I wonder what comparable saving one might achieve if doing 6 minute 40 degree low-flow showers without any other gadgets if coming from the starting point of many homes that probably still have their geysers cranked up to 70 while taking 20 minute showers under a hydrojet?

On 2020/05/28 at 9:08 AM, Jaco de Jongh said:

what happens to that power after the geyser reaches temperature.

I SPECULATE that in real world use it will often likely take most of the day to reach temp since the geyser element is probaly running off a lower supplied voltage?

Btw fairly similar topic came up  here .. (Elon also mentioned on page 2).

6 minutes ago, introverter said:

I SPECULATE that in real world use it will often likely take most of the day to reach temp since the geyser element is probaly running off a lower supplied voltage?

Jip, between 48V-72V in case of the GeyserWise element.