Flat Panel or Evacuated Tubes

[webtailor]

Hi,

I'm about to do a Retrofit for my Geyser. Any experience from you guys regarding the type of technology used?

Shall I go Flat panel or shall I go for Evacuated Tubes?

i'm in Joburg. Is suppose that I should plan for "Frezee", "Frost" and "Hail"...

Any recommended company name is welcomed.

 

[Schicks]

I've recently had a retrofit installation done using flat panels. I added a second 150 litre geyser to increase storage capacity and have 2 x 2sq.m flat panels installed. My electricity consumption has dropped from 320kWh/month to around 18kWh/month.

A friend of mine retrofitted a 20-tube system to his 200 litre geyser and is getting pretty good results although he still runs short of hot water overnight. His electricity savings have been similar to mine.

Both of us are in Jo'burg.

IMO the choice is related to cost. Flat panels are cheaper than evacuated tubes, but evacuated tubes perform slightly better. I'd recommend that whichever way you go, you double your current water storage.

I used an agent for ITS Solar to do the installation for me.

 

[Sinbad]

Tubes. No heat loss to the air, less chance of freezing.

 

[alqassam]

I've recently had a retrofit installation done using flat panels. I added a second 150 litre geyser to increase storage capacity and have 2 x 2sq.m flat panels installed. My electricity consumption has dropped from 320kWh/month to around 18kWh/month.

A friend of mine retrofitted a 20-tube system to his 200 litre geyser and is getting pretty good results although he still runs short of hot water overnight. His electricity savings have been similar to mine.

Both of us are in Jo'burg.

IMO the choice is related to cost. Flat panels are cheaper than evacuated tubes, but evacuated tubes perform slightly better. I'd recommend that whichever way you go, you double your current water storage.

I used an agent for ITS Solar to do the installation for me.

Cost wise what are we looking at? 5 to 10k 10 to 15k 15 to 20k?

 

[SilverNodashi]

Tubes. No heat loss to the air, less chance of freezing.

which?
From whom?
Price?

 

[Sinbad]

which?
From whom?
Price?

I don't know suppliers. I just know the benefits of evac-tube over flat panel

 

[SilverNodashi]

I don't know suppliers. I just know the benefits of evac-tube over flat panel

Oh, I thought you had one installed.

 

[Sinbad]

Oh, I thought you had one installed.

I have an evac-tube geyser. Have had it for about 6 years now so I have no idea if the supplier is even still in business
It's not a retrofit though, it's a complete on-roof unit.

 

[ciscoyeti]

When you retrofit a normal electric geyser you should always go with EVT tubes, flat plates will run a high risk of bursting during winter and when they do your insurance will give you two options either upgrade to tubes or install another flat plate and they will no longer cover it.

 

[Schicks]

Cost wise what are we looking at? 5 to 10k 10 to 15k 15 to 20k?

Flat panel retrofit costs around R12k for a 2.4sq.m panel complete with installation and controls.
Evac tube retrofit (20 tube) costs around R18k installed.

 

[treeman]

There are other options. I see now one can get dual geyser elements that support both 220VAC and PV panel DC. So you just run wires from the solar panels to your geyser. No issues with water leaks, pumps or valves clogging up and you have the benefit of getting PV installed.

 

[Sinbad]

PV panel DC = the most inefficient way to heat your water

 

[eddief1]

PV panel DC = the most inefficient way to heat your water

Im interested in this, can you guys provide more info on the DC options and how they work, never heard of them before

 

[Sinbad]

Im interested in this, can you guys provide more info on the DC options and how they work, never heard of them before

Well you grab like 20% of the energy that hits the collector and convert it to electricity and then convert it to heat.
Would be more efficient to use the electricity to run a heatpump.

 

[P924]

Well you grab like 12-16% of the energy that hits the collector and convert it to electricity and then convert it to heat.
Would be more efficient to use the electricity to run a heatpump.

FTFY

To harvest the same energy as an 18 tube panel, you need about 2kW of PV panels, ideally, you would also have an MPPT controller for that. I leave it up to the reader to estimate costs based on that info.

 

[SilverNodashi]

FTFY

To harvest the same energy as an 18 tube panel, you need about 2kW of PV panels, ideally, you would also have an MPPT controller for that. I leave it up to the reader to estimate costs based on that info.

But if you already have the solar panels on the roof, the MPPT controller and the inverter in place, and you're not constantly using say 5KW of energy, then surely it's not as inefficient as everyone makes it to be?

 

[Sinbad]

But if you already have the solar panels on the roof, the MPPT controller and the inverter in place, and you're not constantly using say 5KW of energy, then surely it's not as inefficient as everyone makes it to be?

If you have "spare" solar generation capacity, then sure. Not sure how many houses would be net exporters of electricity though?

 

[P924]

But if you already have the solar panels on the roof, the MPPT controller and the inverter in place, and you're not constantly using say 5KW of energy, then surely it's not as inefficient as everyone makes it to be?

Well, then you would also stand to gain a lot by using a heat pump instead of resistive heating... This is of course assuming you cannot export your excess energy.

 

[Sinbad]

Well, then you would also stand to gain a lot by using a heat pump instead of resistive heating... This is of course assuming you cannot export your excess energy.

Good point on the heatpump. Up to 4x more efficient than resistance heating?

 

[thehuman]

But if you already have the solar panels on the roof, the MPPT controller and the inverter in place, and you're not constantly using say 5KW of energy, then surely it's not as inefficient as everyone makes it to be?

Evt tubes is between 90% and 70% efficient .
You will need 3 x more roof space / pv pannels to generate same amount of heat .