Dazed and Confused - So Many Options, So Little Money.

[JonB]

Hi all,  I didn't want to hijack Friendly Toast's awesome thread, so I thought I'd wade in separately.
 

Some Background:

I recently bought an old house with 5 (yes 5) geysers. 
No way to consolidate them, the place is stretched out and cavernous, aside from telling some family to suck it up and just not shower or shutting off water to the kitchen and outbuildings, it's just not feasible.

Then we had a 15 day power outage... so my wife gave me that look that said "fix this, now!

 

I am on prepaid.  Monthly bill is R6k. +- 2040 kWh monthly.  She's a hungry house.
I added sonoff switches to measure geyser consumption. Daily load is around 34kWh.
3 of the geysers have non-working heatpumps. 

Option 1 is to fix at cost of R12K (for the 3 total) and reduce load to 1.4kWh per unit.
Option 2 is to take the geysers off power onto PV completely (R60K)
Option 3 is to integrate it using option 1 into by solar PV setup.

House has 5 db boards.  COC issued but she's going to need some work to wire as kitchens / geysers all run of secondary db's

I've had a couple of installers in - everyone's got a product and varying degrees of pricing, but i'd appreciate advice from users

I've been quoted / recommended  a 8kWh backup solution + 10kWh Li batteries and 20  +-400w panels to power it

That's not enough power to take the house off-grid, i know, but it's a start and can keep the lights on in a 15 day power outage and take care of loadshedding so an oke can work and run a few essential geysers.

 

WHAT ARE MY BEST OPTIONS?:

1. Should I separate my geysers from my PV solution and run them independently as has been suggested by one contractor?  Maybe add one or two on the PV and take the non-essentials offline or put them on separate power?

2. Should i spend the money instead on just bulking up my PV to the home and include the geysers in the PV system?

3. Something else?

 

Thanks!

[Scubadude]

Welcome

Your geysers use more power than my family of 6 including 2 geysers! Step 1 would definitely be to get those heatpumps working ... going solar with such a high demand will be extremely costly and / or frustrating. You will also require at least basic geyser timers (e.g. Geyserwise) to get them to run when you are most likely to have excess solar production. The rest of the proposed system sounds like a decent start ... may need more storage, but a good start.

Edited January 27, 2022 by Scubadude

[Steven Burnett]

2 hours ago, JonB said:

Hi all,  I didn't want to hijack Friendly Toast's awesome thread, so I thought I'd wade in separately.
 

Some Background:

I recently bought an old house with 5 (yes 5) geysers. 
No way to consolidate them, the place is stretched out and cavernous, aside from telling some family to suck it up and just not shower or shutting off water to the kitchen and outbuildings, it's just not feasible.

Then we had a 15 day power outage... so my wife gave me that look that said "fix this, now!

 

I am on prepaid.  Monthly bill is R6k. +- 2040 kWh monthly.  She's a hungry house.
I added sonoff switches to measure geyser consumption. Daily load is around 34kWh.
3 of the geysers have non-working heatpumps. 

Option 1 is to fix at cost of R12K (for the 3 total) and reduce load to 1.4kWh per unit.
Option 2 is to take the geysers off power onto PV completely (R60K)
Option 3 is to integrate it using option 1 into by solar PV setup.

House has 5 db boards.  COC issued but she's going to need some work to wire as kitchens / geysers all run of secondary db's

I've had a couple of installers in - everyone's got a product and varying degrees of pricing, but i'd appreciate advice from users

I've been quoted / recommended  a 8kWh backup solution + 10kWh Li batteries and 20  +-400w panels to power it

That's not enough power to take the house off-grid, i know, but it's a start and can keep the lights on in a 15 day power outage and take care of loadshedding so an oke can work and run a few essential geysers.

 

WHAT ARE MY BEST OPTIONS?:

1. Should I separate my geysers from my PV solution and run them independently as has been suggested by one contractor?  Maybe add one or two on the PV and take the non-essentials offline or put them on separate power?

2. Should i spend the money instead on just bulking up my PV to the home and include the geysers in the PV system?

3. Something else?

 

Thanks!

wow, nice project!

I know you say it's not possible, but consolidating/converting to energy efficient geysers seems like it should be a worthwhile exercise.

always cheaper to save wasted power than generate new.

 

[Quintrix]

68kWh per day is fairly high

I would start by  reducing load, ( not necessarily lifestyle changes)

Do you really need all 5 geysers? YES ( I would include them in solar)

smaller heating elements in geysers (2kW)  / replace lesser used with small gas geyser

insulate pipes and geyser blanket ( you have a lot of geysers to feed so protect your gains/heat)

gas for cooking

LED lights

Installing solar while your demand is still fairly high will not remove "the look" as you may not have enough storage and it will just frustrate you. You will in any case start looking at load reduction as soon as your solar is installed.

 

Different approach ( if your budget is truly tight)

Get an Efergy and track your consumption and see how much of that you can shift to "sunshine " hours. Only run your geyser for a few hours during the day and see if it is ok.

This will give you a better idea of what your needs are/system size required. I would guess at least 20kWh storage

 

[Yellow Measure]

It's best to get advice from people who have a range of solutions vs an installer with one product that comes in 3 sizes. If the only tool in the toolbox is a hammer, every problem looks like a nail.

What solar system do you have currently? I am guessing that your water heaters are all on the non-essential loads.

If you have 3 broken heatpumps that you can fix for 12K, that seems to be the immediate and most cost-effective short-term solution. Heat-pumps are hugely more efficient than resistive heating elements, so they will use far less electricity, and they also draw far less power whilst operating (you mentioned 1.5kW, which is high for a heatpump but I gather they are beasties). They also play very well with solar if they are scheduled to only run during the day. This means that you can probably shift the heatpumps to the essential loads (provided that you have capacity).

And definitely consider replacing the elements with lower wattage ones as @Quintrix has mentioned, because depending on your  inverter system, you could be pumping all unused solar energy into these elements if they are small enough (1.5-2kW).

 

[Don]

10 hours ago, JonB said:

I am on prepaid.  Monthly bill is R6k. +- 2040 kWh monthly.  She's a hungry house.
I added sonoff switches to measure geyser consumption. Daily load is around 34kWh.

68 kWh daily power requirement of which 34 kWh is required for geysers. You have a geyser problem. You need to reduce your daily power consumption. Option 1 is a no-brainer. @Quintrixand @YellowTapemeasurehave mentioned the most important things to have a look at. Once you have done everything you can to reduce your daily power consumption, then do you look at what you can run during the day, i.e. schedule your geysers to heat up one after the other. You might decide to keep the oven and aircons, (if you have them) on the grid or non-essential loads side. Then only can you determine what size inverter, batteries and solar panels you require for your system. 

[Nitrious]

Some very good advice so far, 1st step reduce load. 

R4k per heat pump repair seems high, maybe get a few extra quotes. 

I bought my heat pump for R5k as an example from someone who was upgrading theirs, but heat pumps usually represent around R25k each, so definitely worth getting them back in order. 

Getting the heat pumps working should be the first item tackled. 

Once every bit of load has been reduced to the max then size your solar accordingly. 

You may want to consider a borehole if possible. 

Last suggestion is to try and access your bond to finance getting it all sorted. 

Bond finance usually runs about R1k/month per R100k. So you'd have to spend R600k to break even on your R6k/month bill. 

It's easy to see you won't come close to spending that, and going solar will put you ahead every month, in fact you can prudently add your solar savings to your bond monthly, reducing the payment term nicely. 

Depending on your work situation, there are also great business solar tax benefits. 

Don't be in a rush, go step by step, consider everything carefully before proceeding. You're going to have the solar system for a while, make sure it's a good fit. 

Installers can push products/solutions to their self interests rather than yours, so it pays to be careful.

Perhaps this suggestion could work. 

Heat pump repair x3 - solar

Additional geysers - grid

Stove - gas

Measure power requirements of balance including heat pumps, should run a week or two to see power peaks, ave usage, and night usage. 

Then it's much easier to see the way forward, as it's data driven

Last item, 2x 5kw sunsyks inverters are likely better than 1x 8kw inverter, more capacity, more mppt's, similar price point and redundancy in case the worst happens. 

Site unseen, not measured after load reduction example, but with the monthly use case, the actual measuring still needs to be done. 

28x 540w panels

2x 5kw sunsynk inverters

20kwh freedom won battery (this may fluctuate, depending on night usage) 

Around R200k plus installation, you can also Google for prices. 

Generates 2000kwh a month. 

Bond finance R2k/month, but you now have R6k to pay it with. 

Points of interest, add 2x heat pumps if considered necessary and a borehole. 

Then the water bill can also be savings. 

 

Edited January 28, 2022 by Nitrious

[Scorp007]

All I can start with is this is a very nice project. With it will come varied suggestions that would need some understanding as to the main criteria as far as priority.

This would also mean some suggestions that can leave one in a difficult position as to what to do. My input would be to look at the management of the current load and equipment and as mentioned the 1st step MUST be to have data as far as the load profile over the 24 hours are. Without this it is just pulling the trigger and hope to land that trophy kudu bull 

What I have to give credit some some of the suggestions mentioned so far would also be in line with my take on this. Some are not towards improving efficiency which is vital.

1.   Getting a installer who understands solar and not just selling one of his/her 3 options. This is not the typical install. There are such guys around. If it was in the Pretoria area I know who would I suggest to put forward once data of use is available.

2.   Lett us look at the largest load 1st.Changing geyser elements to a lower Wattage only changes the peak power as the expense of longer times to heat water and reducing peaks and/or size of PV system. My take would be to spend the money on getting the heat pumps sorted out. Looking at the typical areas of repairs like gas/pump/control in my mind should also be cheaper. It looks like a worst scenario quote may be without doing fault finding. With heat pumps using only 33-50% of the power to heat water vs an element would introduce a major step towards improving efficiency without changing lifestyle. In reply to a previous input - yes a average heat pump can draw 1.5kW as they are getting older. My 1.2kW which is 9 years old and the only repair was a pump caused due to no strainer on the cold input side. This pump is now using 1.5kW but operation is just as good as when new. Zero cost to lower power use vs a lower Watt element. For 10 months of the year the heat pump will use about 50% of the power of any type of element. I have never wired in my element on my geyser even if the winter times it takes a lot longer to heat water. Then the heat pump uses about the same power as an element for the 2 months of the year. Simply provide a longer timer setting during the few very cold few days.

Due to the fact that the current is lower than an element one could use a far cheaper timer. The controller should already have a few timers and the temp is shown so I would not just add a costly geyserwise per heat pump. If permanent wifi a Sonoff can also be used that give remote switching and timer setting changes. Handy to use when one is away and can get an idea of sun hours during the day to perhaps delay switching when there is cloudy days. Handy when the PV system is in place.

3.   The above improvement cannot be achieved even at 5 times the cost using PV. The 2 remaining geysers could perhaps be used with a lower Watt element. Buying 2 new heat pumps might not be the best return option for them. Here I will run them on PV as a longer term plan and switch on during sun periods but also at different times from 11h00 to 14h30 during peak PV.

3.   With the above in place one can revisit and use the data at hand and then look at the PV side. After only spending R12 000 the saving would be more than about 25% vs current cost of power. Ensure the heat pumps are fitted with the loading valve type of gadgets not to mix cold and hot water the moment you open a hot water tap.

4.   Borehole can also be a costly expense adding to the current load. This is an option to persuade if the value of consumption is known and also what the depth of such an option is known from others in the same area. Our household only uses 15kL even with 2 geysers.

My 2c worth.

[Nitrious]

Repairing the 3x heat pumps and adding 2 more plus changing the stove to gas would substantially reduce the load profile and monthly consumption. 

Heat pumps can be sourced imaginatively and don't have to cost a lot. There's always someone upgrading their heat pump, and the old ones are likely looking for a new home anyway. (but who wants a 2nd hand one right, well I'm happy with mine) 

In addition they can be set to run in time slots, so only one is running at any given time. 

Once this is done, then logging the remaining consumption over a suitable time period (a week or 2) would yield the needed actual solution. 

At this stage the remaining load could be handled by a much smaller cheaper solar system, so significant savings there. 

Subject to the data of course. 

Once the data is established I'd use a drone to take images of the property and generate a 3d rendering of the house. 

Then the proposed installation can be presented in a professional thorough document detailing absolutely everything with visuals showing equipment placement, cabling runs etc, usually a 20 - 30 page document. 

The last information was added so the op has a better idea of what installer quotes and procedures should look like, but often don't. 

 

Edited January 30, 2022 by Nitrious

[Gnome]

Just wanted to mention, even with a heat pump, you are looking at an efficiency of 3:1 (maybe 4:1 if you are lucky).  So 1 watt of energy = 3 watt of heat.

I would seriously consider those solar geyser if I were you.  In summer in SA you can probably go completely of grid in terms of heating that way.

Comparing to your electricity usage, I recently switched to a class B geyser + geyser blanket + pipe insulation and my monthly electricity consumption on that Geyser averages ~37kWh.  Sadly I have no idea what it was before because I only installed the measuring device afterward.  So insulation may help also.

Edited February 3, 2022 by Gnome

[Vaal]

I found that a low flow shower rose, works wonders to bring down hot water consumption if you shower. But sometimes the inhabitants with long hair, complain about struggling to get the soap out of their hair. They just shower a bit longer. 

Another question to the OP, at what temp are your geysers? 55 deg works well as it is still safely hot enough. 

[zsde]

On 2022/02/03 at 3:28 PM, Gnome said:

Just wanted to mention, even with a heat pump, you are looking at an efficiency of 3:1 (maybe 4:1 if you are lucky).  So 1 watt of energy = 3 watt of heat.

I would seriously consider those solar geyser if I were you.  In summer in SA you can probably go completely of grid in terms of heating that way.

Comparing to your electricity usage, I recently switched to a class B geyser + geyser blanket + pipe insulation and my monthly electricity consumption on that Geyser averages ~37kWh.  Sadly I have no idea what it was before because I only installed the measuring device afterward.  So insulation may help also.

2 years ago I had a flat panel conversion done on my electric geyser. That included a Geyserwise controller. No, it's not the most efficient solution. It works well enough though when there is full sun.
Now that I have my electric solar system, by 10 in the morning there is enough solar electric to run the geyser element as well. So I have set the Geyserwise to it's max for electric heating which is 65C. Depending on the Geyser temp in the morning, normally takes between 40mins and an hour to reach that. Then if there is full sun, the flat panel actually pushes it to the absolute max which is 80C during the day. At 80C the Geyserwise disables the electric 12v circulation pump.
So overall I am happy that I am basically off the grid. 
 

[Nitrious]

Someone I chat to (about wind turbines, solar, batteries etc. he's busy with his wind turbine design with cf blades now, I'm busy with my 10kwh li ion battery) almost daily has a Evacuated Tube Solar Collector, which feeds a 200l storage tank (geyser), which then feeds the main geyser This storage tank tops up the main geyser within minutes of hot water being used, keeping the main geyser at almost always set temp. 

I might add its very cost effective, and retrofits your current geyser. 

works well even in cloudy weather (uses uv and solar thermal conversion is very high), his success has got me considering copying his setup, with one key difference, my heat pump will top up the temp as and when needed as well.

 

Edited February 5, 2022 by Nitrious

[Brickman]

On 2022/02/03 at 3:28 PM, Gnome said:

Just wanted to mention, even with a heat pump, you are looking at an efficiency of 3:1 (maybe 4:1 if you are lucky).  So 1 watt of energy = 3 watt of heat.

I would seriously consider those solar geyser if I were you.  In summer in SA you can probably go completely of grid in terms of heating that way.

Comparing to your electricity usage, I recently switched to a class B geyser + geyser blanket + pipe insulation and my monthly electricity consumption on that Geyser averages ~37kWh.  Sadly I have no idea what it was before because I only installed the measuring device afterward.  So insulation may help also.

@Gnome Your figure of 37kwh per month for your Class B geyser seems too good to be true. Standing losses in a class B geyser is roughly 50w per hour = 37kwh for a 31 day month with No hot water useage.

 

[Don]

2 hours ago, Brickman said:

@Gnome Your figure of 37kwh per month for your Class B geyser seems too good to be true. Standing losses in a class B geyser is roughly 50w per hour = 37kwh for a 31 day month with No hot water useage.

Yes, that seems too good to be true. I have 2 x 3kW geysers and supplies water to two separate showers on a daily basis - Geysers hanging on the wall outside the house, no insulation. Insulation will make a difference, but not that much. I heat them up both once per day until the thermostat disconnects the power, then I switch them off till the following day. For January their power usage were 122.54kWh and 139.78kWh respectively.   

Edited February 6, 2022 by Don

[Scorp007]

5 hours ago, Don said:

Yes, that seems too good to be true. I have 2 x 3kW geysers and supplies water to two separate showers on a daily basis - Geysers hanging on the wall outside the house, no insulation. Insulation will make a difference, but not that much. I heat them up both once per day until the thermostat disconnects the power, then I switch them off till the following day. For January their power usage were 122.54kWh and 139.78kWh respectively.   

This seems to be in line with the standing loss as well as limited use of hot water for the showers. I found the larger loss is during the night. With the roof/ceiling cavity at perhaps 45-50 degrees in summer the loss is very low.

One can normally estimate at 2kwh per 24 hours. The latest Kwikot geysers do have a lower loss.

[Gnome]

On 2022/02/06 at 7:30 AM, Brickman said:

@Gnome Your figure of 37kwh per month for your Class B geyser seems too good to be true. Standing losses in a class B geyser is roughly 50w per hour = 37kwh for a 31 day month with No hot water useage.

 

I only have the power figure as recorded by my CBI Astute.  Btw. my geyser is class B, insulated with blanket (+ pipes insulated) + it is in a cupboard inside my house.

With all that said, where did you get the 50w loss?  My GF does this stuff for a living, so if you have the information providing the R value, I'll ask her to calculate my losses based on the ΔT.

Edited February 7, 2022 by Gnome

[Don]

4 minutes ago, Gnome said:

I only have the power figure as recorded by my CBI Astute.

The figures I quoted are also CBI Astute figures. I have been living in the house for 3 years. Two bathrooms and two geysers. One outside each bathroom. Two weeks ago my daughter had a shower. Afterwards I switched on the geyser with the CBI Astute and nothing happened. I switched on the other geyser I heated up an hour earlier and it switched on. That was not supposed to happen. I then realised both bathrooms are on the same geyser. The one geyser only serviced the kitchen. I had the plumber come in and split the bathrooms to use their own geyser. @Gnome, are you sure that geyser is actually being used?

[Gnome]

11 hours ago, Don said:

@Gnome, are you sure that geyser is actually being used?

Yeah I only have 1 geyser (apartment).  I'll reset it this month and test again.

[Calvin]

On 2022/02/06 at 7:30 AM, Brickman said:

Standing losses in a class B geyser is roughly 50w per hour

The actual losses will vary a lot, mainly on temperature differential.  Clearly the difference between the geyser's setpoint and the ambient temperature is key.  The other major variable is the environment- a draughty ceiling space may result in forced convection, whilst a cupboard will have only natural convection.

Having a geyser installed in a cupboard is ideal (from this perspective anyway) - essentially a small space that will quickly become warm.  ΔT could be as low as 15-20˚C, natural convection only.  Contrast that with a geyser with a high setpoint in a draughty ceiling space in mid winter - ΔT could be 50˚C or more plus forced convection.

So, bottom line: standing losses (averaged daily) could probably vary from 20 to 200W, or about 0.5 to 5 kWh/day.  Given @Gnome,s circumstance his 37kWh/month is very possible.

 

[Brickman]

On 2022/02/06 at 9:02 PM, Gnome said:

I only have the power figure as recorded by my CBI Astute.  Btw. my geyser is class B, insulated with blanket (+ pipes insulated) + it is in a cupboard inside my house.

With all that said, where did you get the 50w loss?  My GF does this stuff for a living, so if you have the information providing the R value, I'll ask her to calculate my losses based on the ΔT.

@Gnome the 50w figure is what is quoted by Kwikot for their Class B geyser as opposed to 108 w/hr on their standard offering.

[Don]

18 hours ago, Calvin said:

So, bottom line: standing losses (averaged daily) could probably vary from 20 to 200W, or about 0.5 to 5 kWh/day.  Given @Gnome,s circumstance his 37kWh/month is very possible.

H Calvin, I don't think so. 37kWh/month / 30 = 1.2kWh/day. That means that after having a 10 minute shower for only one person and using hot water 2- 3 times a day in the kitchen to wash the dishes, it will only take 24 minutes a day with a 3kW element to get the geyser up to temperature again? I don't think so.

My 1 geyser supplies the bathroom where only my daughter showers once per day and supplies hot water to the kitchen for doing the dishes. Pretty much the same scenario as @Gnome. Usage for January = 139.78kWh / 31 =  4.5kWh/day. Granted, my geyser hangs on the outside wall with no insulation. If I insulate my geyser and pipes and I get a 30% saving in energy (optimistic), my power usage should the reduce to 3.2kWh/day. That is just over an hour a day with a 3kW element. That sounds about right to me. Therefore, for a month at least = 97.8 kWh. Gnome's usage is about 35% of that? Seems way to low for me. 

22 hours ago, Gnome said:

I'll reset it this month and test again.

Lets wait and see what he uses this month. 

[Calvin]

2 hours ago, Don said:

H Calvin, I don't think so. 37kWh/month / 30 = 1.2kWh/day. That means that after having a 10 minute shower for only one person and using hot water 2- 3 times a day in the kitchen to wash the dishes, it will only take 24 minutes a day with a 3kW element to get the geyser up to temperature again? I don't think so.

Truth be told, I also think it is unlikely, but it is possible.  The fact that he has a class B geyser plus an insulating blanket plus pipe insulation plus it is mounted in a cupboard plus it is summer now means that the standing losses will be very low.  It all depends on the geyser's setpoint and hot water consumption. We don't know what the setpoint on the geyser is, we don't know how many showers per day, and for how long, we don't know if he uses hot water for dishes - perhaps he has a dishwasher.

 

[Gnome]

Haha guys, I feel like I nerd sniped everyone here.  I'm perfectly willing to accept I have a measurement error

My ambient atm is around 30 degrees (in my flat, not 100% sure about cupboard, will check).  I don't turn on the geyser based on temperature at all (I mean there is a max obv, around 60℃ but these thermostats aren't exactly accurate).  I only turn it on for 30 minutes twice a day.

Edited February 8, 2022 by Gnome

[Scorp007]

2 hours ago, Gnome said:

(I mean there is a max obv, around 60℃ but these thermostats aren't exactly accurate).  I only turn it on for 30 minutes twice a day.

Yes the actual scale perhaps not. What I have measured is the power used by a 3kw element and found it to use as little as 200Watt which means it went up by just over 1 degree before it switched off again. This is without any water used from the previous switch on. Power measured with an electronic power meter which is quite accurate if compared with the munic meter.