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You are going to need about 3 Kwh to heat a 55 lt calorifier up from 15 to 60 deg C so a 300 watt element is going to take 10 hours, do you get 10 hours of sunshine after your batteries are fully charged? Calculation here

Edited by ditchcrawler
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12 minutes ago, ditchcrawler said:

You are going to need about 3 Kwh to heat a 55 lt calorifier up from 15 to 60 deg C so a 300 watt element is going to take 10 hours, do you get 10 hours of sunshine after your batteries are fully charged? Calculation here

Heat rises, reason why water tanks take from the top, so you don’t need to heat all the water up to get hot water.

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20 minutes ago, ditchcrawler said:

You are going to need about 3 Kwh to heat a 55 lt calorifier up from 15 to 60 deg C so a 300 watt element is going to take 10 hours, do you get 10 hours of sunshine after your batteries are fully charged? Calculation here

Doesn't look to attractive does it however if the following was to apply

50 litres raised by 5deg C using 300w would take 1 hour spare capacity

Would this be enough to stop existing hot water cooling down if so then the minimal cost may be worthwhile even if it is only for a few months a year.

Basically for an outlay of circa £50 everything you do get from it is then free. As I very rarely hook up then for me there doesn't really seem to be a downside 

In essence there would be minimal benefit but at least the minor benefit would be free after initial small outlay

Edited by reg
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3 minutes ago, reg said:

Doesn't look to attractive does it however if the following was to apply

50 litres raised by 5deg C using 300w would take 1 hour spare capacity

Would this be enough to stop existing hot water cooling down if so then the minimal cost may be worthwhile even if it is only for a few months a year.

Basically for an outlay of circa £50 everything you do get from it is then free

My argument goes the other way: Every degree you warm the water for free is warmth you don't need to provide via gas or diesel, so in theory it will save you some money longer term.

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1 minute ago, TheBiscuits said:

My argument goes the other way: Every degree you warm the water for free is warmth you don't need to provide via gas or diesel, so in theory it will save you some money longer term.

Which is what I said after the first line(which I've just edited by the way to clarify by preceding it with "looked at like that..") my end line says

 

6 minutes ago, TheBiscuits said:

Basically for an outlay of circa £50 everything you do get from it is then free

I think we are in agreement 

ETA

Looks like forum software has decided you said that and not me, so be it

 

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So what happens if your solar panels are producing an excess over what is needed for battery charging of less than 300W? Can this power be used to run a 300W immersion heater? Since the immersion is a pure resistive load, trying to make it take less than the rated wattage will surely result in the voltage falling, and hence no battery charging.

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2 hours ago, David Mack said:

So what happens if your solar panels are producing an excess over what is needed for battery charging of less than 300W? Can this power be used to run a 300W immersion heater? Since the immersion is a pure resistive load, trying to make it take less than the rated wattage will surely result in the voltage falling, and hence no battery charging.

Most controllers only switch the relay on when in float.    The outback has a PWM mode where it can reduce the immersion wattage,  I’m not sure if it can do this whilst charging as well tho.  Anyone of a outback that can confirm?

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