Solar geyser or more panels?

[Richard Mackay]

1 hour ago, gbyleveldt said:

Flip side of the argument is that, with more panels, you have more power earlier in the morning and later in the afternoon. Also, on cloudy days, there's more potential PV available. All else being equal, adding extra PV panels to a system is cheap for the benefit. Futhermore, if you using a blending type inverter (Goodwe**gasp**, Sunsync), it can feed power to non-essential loads (like pool pump or geyser), even if you set grid export to zero. The trick is to set these high consumers to draw power during daytime when PV is at a peak. So, you get the benefit of PV on non-essentials without having to connect these to the backup side of the inverter. Even if there's not enough PV for a certain device on the non-essential side, the balance of what's available can still be fed to the non-essentials and the shortfall from the grid, automagically. This significance of this took me a while to comprehend, but it's this capability that sets the expensive inverters apart from the cheap ones.

Agreed! Just walk me through how you set the 'blending' to power these high consumers to only draw power from available PV power only.. 

[FixAMess]

1 hour ago, gbyleveldt said:

Flip side of the argument is that, with more panels, you have more power earlier in the morning and later in the afternoon. Also, on cloudy days, there's more potential PV available. All else being equal, adding extra PV panels to a system is cheap for the benefit. Futhermore, if you using a blending type inverter (Goodwe**gasp**, Sunsync), it can feed power to non-essential loads (like pool pump or geyser), even if you set grid export to zero. The trick is to set these high consumers to draw power during daytime when PV is at a peak. So, you get the benefit of PV on non-essentials without having to connect these to the backup side of the inverter. Even if there's not enough PV for a certain device on the non-essential side, the balance of what's available can still be fed to the non-essentials and the shortfall from the grid, automagically. This significance of this took me a while to comprehend, but it's this capability that sets the expensive inverters apart from the cheap ones.

The Goodwe can feed back into the household load without feeding back into the grid. Everything on the near side of the CT meter, geyser (all non essential loads)  + essential can still be fed from the PV without feeding back into the grid..I'm sure the Sunsync can do the same or have I got the entire story wrong?

The essential loads is only for when the grid is down, so then, yes your geyser (on non-essential side) will not get fed, but when the grid is up and you're feeding back zero into the grid, the household loads are still fed...I hope!!

[Craigm]

2 hours ago, gbyleveldt said:

Flip side of the argument is that, with more panels, you have more power earlier in the morning and later in the afternoon. Also, on cloudy days, there's more potential PV available. All else being equal, adding extra PV panels to a system is cheap for the benefit. Futhermore, if you using a blending type inverter (Goodwe**gasp**, Sunsync), it can feed power to non-essential loads (like pool pump or geyser), even if you set grid export to zero. The trick is to set these high consumers to draw power during daytime when PV is at a peak. So, you get the benefit of PV on non-essentials without having to connect these to the backup side of the inverter. Even if there's not enough PV for a certain device on the non-essential side, the balance of what's available can still be fed to the non-essentials and the shortfall from the grid, automagically. This significance of this took me a while to comprehend, but it's this capability that sets the expensive inverters apart from the cheap ones.

This is exactly my intention, nail on head!

 

My idea at the moment, is to set the pool to run when the PV gets up high enough, and then (if I stick with electric geyser on AC) to heat the geyser early afternoon, turning the pool off for the time if required.

[Craigm]

1 hour ago, Krokkedil said:

I did Not read all the replies if I say something that has been said then it just confirms 

1. Get the best inverter you can afford. No less than 5kw. 

2. Get Lithium Battery and skip the AGM or lead acids. I know it is only for backup but I can promise you that this is a better investment.

3. Get the maximum amount of panels your inverter can use. Or get a popular wattage like the 330w or something you know you will be able to get more off.

4. Ensure you have enough sun lots of people forget this part. I have a house in Pretoria with huge trees that my wife dis not allow me to cut down. With 9 panels i struggled to make 2kw. I moved to cape town and the same 9 panels push over 2,5kw from about 10-4. i make close to 12kwh a day.

5. Place as much of your house over to the solar- forget about the load shedding backup nonsense- I save around R800 pm on a small 2,4kw inverter. When I was in Pretoria my pool pump 1,2kw use to run from 10-2 on the inverter, If I wanted to use the Borehole i just switch off the pool pump. 

If you spend R100k and then save R800pm then it will take 10 years to pay back the system. 

I hear you on the lithium batteries. However, what I intentionally did not mention in my OP was that my startup budget is around R70k. If I go R30k inverter, R20k panels and (thumbsuck) R20k installation, I hit my budget. The wife wants backup lights "for the system and investment to make sense to her". The extra battles we face! So batteries are on my radar, but might not make it into the initial install. Same story with the panels. As I do not know what my loads will be exactly yet, I am speccing a smaller system to get it up, then will happily add panels as required. I will look into the best panel closer to the time, but I have access to a commercial solar distributor that might be able to help me with panels.

I have enough space for all panels to have full sun, no trees nearby. My only concern is that the pitch of the roof is high, might result in a different challenge. I think its about 45 degrees. Panels will face NNW

 

I want the whole house to run on solar during the day. My current daytime idle load is 250-300w, so the system should not have to handle much more (except the additional pool pump which will run in the day).

[Pietpower]

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[gbyleveldt]

2 hours ago, Richard Mackay said:

Agreed! Just walk me through how you set the 'blending' to power these high consumers to only draw power from available PV power only.. 

That one is a challenge on the Goodwe (I’m currently working on the driver to remedy that issue), but I believe the Sunsynk already has a setting to prevent battery use on non-essential items. It’s one of the reasons I point people to Sunsynk rather than Goodwe.

Edited November 15, 2020 by gbyleveldt

[Pietpower]

2 hours ago, gbyleveldt said:

That one is a challenge on the Goodwe (I’m currently working on the driver to remedy that issue), but I believe the Sunsynk already has a setting to prevent battery use on non-essential items. It’s one of the reasons I point people to Sunsynk rather than Goodwe.

Yip, it is a challenge.  I try to manage the load with timers rather than the inverter.  The pv gives some charge to the batteries. Then the geyser comes on and gets power from pv and batteries not using eskom. When the geyser is finished the pv charge the batteries again.

If the geyser did not use any battery power then I would have very low load in the afternoon and pv panels would be in 'idle' mode with nothing to provide power to.

[Craigm]

Thanks to everyone for your input, I really appreciate it! This is a great forum!

 

I think I am going to go with the Sunsynk 5kW. Now to find one. Any recommendations on where to get one at a good price? Preferably local (Pretoria). 

Any current specials, or Black Friday specials?

I can only install in Feb, but I doubt prices will go down by then (might go up?).

[Pietpower]

Just to reply to the heading of solar geyser or more panels.

My experience was that it was more economical to use the system I have and add a few extra panels to heat the hot water.

BUT

During winter our 200L geyser does not last to the next morning if we only heat it once a day and we need to heat at night time. Then I use Eskom and battery power. 

Instead of adding more batteries at high cost I decided to add storage in the form of a second inline 150L geyser. Two 3kW elements might be too much so I decided to use a cheap flat plate collector on the first geyser. (some day I will install it)

For now only one geyser is electrically connected and I use a pump to circulate and heat the second geyser. Interesting enough the one geyser alone used about 10kWh per day and heating both now only adds another 2kWh per day.

[Gerrie]

7 hours ago, gbyleveldt said:

That one is a challenge on the Goodwe (I’m currently working on the driver to remedy that issue), but I believe the Sunsynk already has a setting to prevent battery use on non-essential items. It’s one of the reasons I point people to Sunsynk rather than Goodwe.

I had a look at the sunsync manual and see they have a non-essential output that can be used for something like a geyser or pool pump that can be switched on when the battery voltage is within preset limits, that is definitely a nice feature to have as that could solve heating water worries. The only issue I have with sunsync is their warrantee that seems to cover them from every angle, only their approved company’s can install the units and the unit needs to be serviced only by their company otherwise you could loose the warrantee. 

[Craigm]

3 minutes ago, Gerrie said:

The only issue I have with sunsync is their warrantee that seems to cover them from every angle, only their approved company’s can install the units and the unit needs to be serviced only by their company otherwise you could loose the warrantee.

Is there a list of approved installers somewhere? 

[Gerrie]

I think MDSolar is the go to guys as I got the manual with their name on.

[Yellow Measure]

The powerforum has a list of commercial suppliers here.

Edited November 16, 2020 by YellowTapemeasure

[DDD]

On 2020/11/14 at 7:43 PM, Richard Mackay said:

Bear in mind that if you install many panels and plan to use the power as required (e.g. to heat your geyser) you will have the challenge of managing this, especially if you want this to be automated.

As  far as solar PV for your geyser have a look at the Geyserwise Dual. It is a dedicated system (3 or 4 panels) but they have a clever system of using DC direct from the panels to heat the PTC element via a MPPT. This has to be more efficient than powering a 220V geyser element from an inverter. 

Dedicated means you can not use it for anything else.  Dedicated means than when the solar geyser is at optimum temp the panels are not used and the power on it is wasted

One of the best ways is to get a solar circulation pump. Glass tubes or water heater on the roof. Circulate the hot water through your conventional heater when there is son.  I have a 55 000L koi pond my pump runs 24/7 365 , a 10 000 L swimming pool 220V geyser I also use my own water and use an electrical pump for me and my neighbor. I have a grid tied system I have my electricity usage down to +/- 10Kw per day. Will now jack it up to get paid by the COCT.

There are other ways of doing doing tricks when Eskom is dead.  You do not need those fancy batteries and batteries controllers and what ever. You can never get your ROI with them. SImple once they paid they have to be replaced ....
Therefore rather get a glass tube system and circulated the hot water put a cheap timer on your geyser and voila it works immediately.

I got my electricity bill down to +/- R180 p with all of the above. 

Edited November 16, 2020 by Erastus

[Richard Mackay]

49 minutes ago, Erastus said:

Dedicated means you can not use it for anything else.  Dedicated means than when the solar geyser is at optimum temp the panels are not used and the power on it is wasted

One of the best ways is to get a solar circulation pump. Glass tubes or water heater on the roof. Circulate the hot water through your conventional heater when there is son.  I have a 55 000L koi pond my pump runs 24/7 365 , a 10 000 L swimming pool 220V geyser I also use my own water and use an electrical pump for me and my neighbor. I have a grid tied system I have my electricity usage down to +/- 10Kw per day. Will now jack it up to get paid by the COCT.

There are other ways of doing doing tricks when Eskom is dead.  You do not need those fancy batteries and batteries controllers and what ever. You can never get your ROI with them. SImple once they paid they have to be replaced ....
Therefore rather get a glass tube system and circulated the hot water put a cheap timer on your geyser and voila it works immediately.

I got my electricity bill down to +/- R180 p with all of the above. 

I hear what you're saying but 3 PV panels won't bust the budget! (or be a significant loss to the main PV panels)

Also the panels are cheap (and getting cheaper). They are hardy with a simple installation. No piping of water etc.

[DDD]

7 minutes ago, Richard Mackay said:

I hear what you're saying but 3 PV panels won't bust the budget! (or be a significant loss to the main PV panels)

Also the panels are cheap (and getting cheaper). They are hardy with a simple installation. No piping of water etc.

PV panels not as effective as glass vacuum tubes. Very simple a PV panel is 18% effective. A vacuum tube with a small "manifold" you can give you 85C You can not get the same with 3 PV panels.
Do not think I am against PV its simply not as effective as a vacuum glass chamber and even on day when PV panel does not generate the vacuum tubes generate heat.
 

To heat a geyser and save on electricity you can not beat a vacuum tube system.
Else its better then to use grid tied and stack solar panels with a timer.  But the last option in my opinion is to get a dedicated 3/4 panel system. If you calculate the ROI they are one of the worst models.

3PV panels = R 7500 then you need installation ...   A vacuum tube system that one can expand or what ever is in the same $ range and more effective for heating water WHEN THERE ARE CLOUDS is where they stand on their own.

 

 

Edited November 16, 2020 by Erastus

[Pietpower]

2 hours ago, Richard Mackay said:

I hear what you're saying but 3 PV panels won't bust the budget! (or be a significant loss to the main PV panels)

Also the panels are cheap (and getting cheaper). They are hardy with a simple installation. No piping of water etc.

You were talking about efficiency of connecting them direct to the geyser.

Yes it is more efficient to connect direct to the geyser as opposed to connecting via inverter but the lost power far outweigh the efficiency calculation. Iow efficiency is much higher via an inverter if you use balance of the power. 

If you have 12 panels then adding 3 is a significant increase.

 

[DDD]

48 minutes ago, Pietpower said:

You were talking about efficiency of connecting them direct to the geyser.

Yes it is more efficient to connect direct to the geyser as opposed to connecting via inverter but the lost power far outweigh the efficiency calculation. Iow efficiency is much higher via an inverter if you use balance of the power. 

If you have 12 panels then adding 3 is a significant increase.

 

Now you are moving the goal posts.

Its logical that if you have PV installed add PV expand your solr panels
I think the question was when starting.

When starting the order of MAX ROI is:

1. Geyser with vacuum tube tied into existing geyser.  No fancy electronics a geyser is nothing but a dummy load that sucks power.  The less power the less heat. nothing you can do about it. The only way you save is finer control and more of time. That is done with a normal inexpensive timer that you can set till you have optimum. 7 day timer is better as Sundays, Saturdays normally one sleeps later bath later and save by switching the geyser later on.  The fancy electronics are there to fool people and then you pay more for a timer cost R 320 at Builders.
2. Gas stove You can't beat the heat and the cost of it with natural gas.
3. The rest of electrical stuff

If you start new the most expensive way is fancy batteries and fancy system that people get caught with....

But to start saving is simple.  GAS tube heater with cheap timer and maybe circulation pump.
Then with the savings buy a gas stove.
Then get grid tied inverter.

To get rid of Eskom outages there are very cost effective ways of doing power back up.

Thus far I did not spend R45K and I am getting money back and if you wish Eskom load shedding not an issue.

If you fix the goal posts to the best way TO START this is the way to go. It is in line of whats costing money and what is saving.

Let me explain I was quoted R130K for a system not grid tied ....
A total waste.

I bought a second hand gas tube 100l geyser for R900. Then a small pump R 320 few pipes and I have 350L sun warmed solar geyser.  During the day with grid tied It uses sun in any case.  Glass vacuum tubes never ages.  The fiberglass 100l never rusts....

Will I have these fancy hybrid systems.

I personally believe that are far better cost effective ways to do it ..

And I have proof of it.

it.

[gbyleveldt]

16 hours ago, Gerrie said:

I had a look at the sunsync manual and see they have a non-essential output that can be used for something like a geyser or pool pump that can be switched on when the battery voltage is within preset limits, that is definitely a nice feature to have as that could solve heating water worries. The only issue I have with sunsync is their warrantee that seems to cover them from every angle, only their approved company’s can install the units and the unit needs to be serviced only by their company otherwise you could loose the warrantee. 

At least they won't flip you the bird as Goodwe would. Warranty without any support is worth as much as the text on their website. If I come across as bitter then you are reading me correctly

[gbyleveldt]

22 hours ago, Pietpower said:

Yip, it is a challenge.  I try to manage the load with timers rather than the inverter.  The pv gives some charge to the batteries. Then the geyser comes on and gets power from pv and batteries not using eskom. When the geyser is finished the pv charge the batteries again.

If the geyser did not use any battery power then I would have very low load in the afternoon and pv panels would be in 'idle' mode with nothing to provide power to.

I used timers as well in the beginning, but it was a pain to manage that and prevent the battery feeding back into the grid when the load wasn't drawing a lot of power.

I just got the dynamic On-Grid DoD change working on the HA driver last night. Still a few bugs to fix, but it works. I can now leave the inverter in General mode but leave DoD at 100% during the day (thus not using batteries at all for loads) and change it to, say 30% at night after all the heavy consumers are done. I can even detect when the high consumers kick in and dynamically change DoD so the inverter wouldn't use battery for those. This change is immediate without the inverter needing a restart. Now I can decide when the inverter should use the batteries in on grid mode without them getting murdered when someone uses the oven or the geyser kicks in when there's no PV.

All these workarounds for something that Goodwe can simply fix in their software.

[Pietpower]

2 hours ago, Erastus said:

Now you are moving the goal posts.

I am changing the goal posts?  While you are moving over to gas stoves and gas heaters?

PS: My reply was isolated to Richard's comment of solar panel on the inverter vs solar panels direct on the geyser vs efficiency.

[DDD]

4 hours ago, Pietpower said:

I am changing the goal posts?  While you are moving over to gas stoves and gas heaters?

PS: My reply was isolated to Richard's comment of solar panel on the inverter vs solar panels direct on the geyser vs efficiency.

Sorry misunderstood. Sometimes 1 tales are difficult!!

[Richard Mackay]

On 2020/11/16 at 11:10 AM, Pietpower said:

You were talking about efficiency of connecting them direct to the geyser.

Yes it is more efficient to connect direct to the geyser as opposed to connecting via inverter but the lost power far outweigh the efficiency calculation. Iow efficiency is much higher via an inverter if you use balance of the power. 

If you have 12 panels then adding 3 is a significant increase.

 

I'm not following your argument: Please clarify 'lost power' and 'balance of the power'

[Pietpower]

Same thing.

When you connect the panels direct to the geyser there will be times when the geyser is not requiring any further heating.  The sun will likely still be shining on the solar panels although they will not be producing power. That is the potential 'lost power'.  

If the panel can potentially produce say 100% power a day and you only use say 60% for hot water heating the lost power is 40% or the 'balance of the power available' is 40%. Connected to an inverter you can use that 40% for something else or battery charging.

[Richard Mackay]

8 hours ago, Pietpower said:

Same thing.

When you connect the panels direct to the geyser there will be times when the geyser is not requiring any further heating.  The sun will likely still be shining on the solar panels although they will not be producing power. That is the potential 'lost power'.  

If you require the panels to power the geyser all the time set the temperature to mox!