ditchcrawler Posted April 19, 2018 Report Share Posted April 19, 2018 (edited) 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 April 19, 2018 by ditchcrawler Link to comment Share on other sites More sharing options...
Robbo Posted April 19, 2018 Report Share Posted April 19, 2018 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. Link to comment Share on other sites More sharing options...
reg Posted April 19, 2018 Report Share Posted April 19, 2018 (edited) 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 April 19, 2018 by reg Link to comment Share on other sites More sharing options...
TheBiscuits Posted April 19, 2018 Report Share Posted April 19, 2018 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. Link to comment Share on other sites More sharing options...
reg Posted April 19, 2018 Report Share Posted April 19, 2018 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 Link to comment Share on other sites More sharing options...
ditchcrawler Posted April 19, 2018 Report Share Posted April 19, 2018 35 minutes ago, Robbo said: 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. Depends how long he stands in the shower for Link to comment Share on other sites More sharing options...
David Mack Posted April 19, 2018 Report Share Posted April 19, 2018 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. Link to comment Share on other sites More sharing options...
Robbo Posted April 19, 2018 Report Share Posted April 19, 2018 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? Link to comment Share on other sites More sharing options...
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