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anteror
Senior Member

Joined: 06/10/2009
Location: Finland
Posts: 189

Posted: 09:12am 26 Aug 2013

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I begin a new discussion about this..because we in Finland really have
made a lot of work and testing for this, to use electric PV panels,
for heating water etc
We have not anykindof feed in tarif..

, that almost all our neighbour
countries have, SO..
We have this system in many places and we have a good reason to do so.

First.. some points, why;
-You can easily use existing systems to have solar power.
You do not have to buy any new water heater(s) or heat transfer units, to use
this system.
You do need any pumps, tubes and their thermal insulation, penetrations with tubes,
heat exchange fluids, sensors..etc

You just need PV panels to make the power for water heater, floor heating etc
and connect the panels with high voltage without anykindof controller directly to water heaters resistance unit.

We have connected the panels to produce high voltage, in series.
We have 230-240V system in Finland, so we have connected 5-40-100.. units to make
150-240V to water heaters etc

Smallest water heater I know, that is working with PV solar is just 50L,
but most are 300-3000L water heaters.

If you connect the PV panels to water heating, the most important thing is that
you found the right resistive load.

IT is very easy.
In every solar panel there is the value for optimal value for optimum voltage under load in tecnical details.
When you connect panels and found this in the best production time, about
12-13, and the voltage is right, as in the technical detail says, under load.
That is it.

WE have used this unit, when you want MORE.. power electronic relay
Carlo Gavazzi 1000V Dc solar connecting relay; RGS1D1000D25KKE

http://www.productselection.net/PDF/UK/rgc1d.pdf

You can control with this relay with existing mechanical bi metal heat relay,
in the water heater.
We have connected for example 20 units of solar PV panels in series to make 5-6kw
and 500-600V Dc, or 10+10 in parallel to make 250-300V Dc etc
PV panels 235-300W.
Biggest system to heat water, I have seen is over 500Kw and it did not need any relay, because the energy storage was so big.
You need this relay for extra high power for water heater, because mechanical bi metal heat relays do not stand high DC power.
With this electronic relay without tips, you can connect.. what power you want for too litle water heater, that is conected to floor heating, radiators etc
OR.. you have a BIG family and teenagers are in the shower all the time etc

In places that you do not have mechanical heat relay we have used this cheap and
good digital thermostat. You can program it to work, with many ways.
It works with the same Dc voltage, as Garlo Gavazzi
electronical relay;

http://www.ebay.com/itm/Automatic-Digital-Temperature-Contro ller-Thermostat-12V-110V-220V-Control-Switch-/160809424363?v ar=460074411046

I can understand if you have feed in tarif, so this system is..

BUT this system will give you water, or floor heating etc without any
heat loss and it is easy and a bullet proof system, without any moving parts..

ANYTIME when it shines, THE POWER WILL burst out to your water heater etc
WITH FULL POWER without any loss or delay, even in VERY cold conditions.
AND all this..

with just normal cheap wire..

Also..!;

When you need emergency power(and you wil need, some day..), you can easily connect
the PV panels in parallel to produce loading power to use at home.. with inverter(s)
If your country does not have feed in tarif, but will have some day..
you can easily connect the PV panels to product power, to the grid and
get profit etc

SOME.. sunny day

Antero

Edited by anteror 2013-08-31

vk4kij
Newbie

Joined: 04/05/2010
Location: Australia
Posts: 9

Posted: 04:44pm 03 Sep 2013

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Hi Antero,

All interesting.

I am currently thinking about what I need to do with my hot water needs.

I have a small (65l) LPG hot water storage system, which does a 45kg bottle of LPG every 6 weeks.

I was thinking of putting some hot water panels up, along with the pump, and the pipes, probably a larger storage tank, etc.

Using PV panels certainly makes things easier, I imagine the storage tank heat losses would be less over the LPG one.

But.

I would still need a way of heating the water if there was not enough sun for the day.
The cost. Second hand hot water panels seem to be cheaper, at least over here.
More roof area would be taken up with PV panels compared to hot water panels.

I suppose I need to think more on the advantages and disadvantages of either way.

Ian.

anteror
Senior Member

Joined: 06/10/2009
Location: Finland
Posts: 189

Posted: 09:10am 04 Sep 2013

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To vk4kij;

It is very challenging to use so litle water heater for solar.

Here, how you need power for water heating;

1000L water, needs 1,167 Kwh energy to warm one degree Celsius.
100l water needs 0,1167 Kwh energy to warm one degree Celsius.
300l water needs 0,350 Kwh energy to warm one degree Celsius.

1liter is= 0,22 gal, or 35,2 oz

You need at least, 300l water heater, to use solar reasonably.

We have used 1-2Kw solar PV power to heat 300l water heater.

With 1kw solar PV panels, with sunny day you get 8-10Kwh energy.

SO.. it will warm the 300l, in a sunny day;

8kwh warms 300l water / 0,350= 22,8 degrees Celsius.

Etc

You must have energy storage to use solar or wind power,
with a reasonable way.

We have made water heating resistors by ourselfes with Kanthal resistor
wire.
Pottery enthusiasts use Kanthal resistor wire, to their furnaces.
It can take very high temperatures and do not brake.

You can then conect the PV panels to any voltage and found the right
resistance load.
You must have clamp ammeter to DC amps and volt ammeter.
You use car starting gables.
One end to start point and you slide the other head with resistance
wire to find the right resistance load,
when amps X volts = power in wats, is the best.

Then you cast this resistance wire in concrete, or in fireproof mass,
to fit in the outside of your water heater and insulate it, with fireproof
insulation.
Very cheap and everlasting resistor, to stand any water quality..
and can be installed to any water heater, or mass heater.

Also for wind power with any voltage and water power etc

Antero
Edited by anteror 2014-01-21

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