methley
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Discuss Solar Panel immersion heater automatic switch. in the Solar PV Forum | Solar Panels Forum area at ElectriciansForums.net
not that I know of I think the only way to calculate real power and control the proportional controller is to use software.Cool .. Thank you.
Could we do the entire system with the 2 CT's + controller and without using a microcontroller ? any comparator circuits using LM series ?
Just found Solar Panel Immersion Heater Switch - Use Surplus Power To Heat Water | eBay
Has anyone tried one of these?
Do not know if there is any garantee with it but have asked the question.
To be cost effective it has got to last several years
I wouldn't buy the £168 + £8 p&p ebay one as there's a good chance it will be running your immersion heater off the grid. If you pay 3p/kW for gas and 15p/kW for electric then running this off the mains at a 1:5 ratio or for 10 mins per hour will negate any savings made. Anything more than 10 mins for hour of greater than 500W baseload at your property (kettles, TVs etc on-top of fridges/freezers) will start actually costing you money!
I'm amazed it's sold so many, especially as you could do the same by simply flicking the switch on your immersion heater when your solar meter is saying 1.5kW or greater. You'd probably be better off with a timer from Argos which you only turn on during peak hours and turn it off when the weather forecast is bad.
Anyways... I've been looking into this and you will need a 1kW immersion heater ideally rather than the 3kW most people have. I've looked into stepping a 3kW down to 1kW via 220 to 110V, but it's not cost-efficient.
I'm looking to make one of these for myself, which will automatically turn on the immersion heater when the solar is exporting 1kW or more. It will automatically turn off at below 1kW export, so will never take electricity from the grid. If anyone, would like me to try and make one for them, please PM me. I'll probably need some pics of your install (consumer unit, gen meter etc) and details of what exactly you want. My install is going to be quite simple but I don't mind making it a bit more complicated for your needs if I can.
Bear in mind... I will be doing this as a hobby not a business!!! So please be kind!!!
Anyways... I've been looking into this and you will need a 1kW immersion heater ideally rather than the 3kW most people have. I've looked into stepping a 3kW down to 1kW via 220 to 110V, but it's not cost-efficient.
I think the benefits will probably be small... between £50 and £100 per year for gas, bit more for economy 7, probably double or triple for electric / oil / lpg. Once I figure it all out I'll post what I think and hopefully people can correct my inevitable mistakes.
I've got gas, so will get the least payback, and I want to make the payback within a few years, so alot better than Solar PV itself. If energy prices rise then you are protected even more. I'm thinking if it warms up the water during the day, the gas boiler won't be needed, so for at least 3 months of the year I won't need to pay to heat the boiler up for showers, baths, washing up etc.
If everyone just made one for themselves then yes it would be alot of effort for little benefit, but I'm quite interested in getting different ones working, so for me it's a bit of fun too. I've got a kit-car, I could've bought it cheaper already made... but where's the fun in that?
Appreciate your thoughts... constructive criticism will stop me spending way too long on this or making mistakes so please keep them coming!
Thanks
this is a link to the schematic of the current circuit
Detailed energy monitor system design | OpenEnergyMonitor
you make this circuit board and the take a cable from the pwm arduino pin to the 0-5v of the proportional controller.
I would definitely recommend a fully proportional power diverter rather than a stepped type. I have built a Crydom based diverter based on a circuit supplied by a member of this forum.
If this last weeks production is anything to go by the proportional system will really come into it's own in the winter.For example this week my 4kW WSW system has only produced around 4 to 6 kWh per day but the diverter has sent 2.5 kWh of the 4 kWh and 4.6kWh of the 6kWh to the immersion. This is everything not being used for other things like base load, dishwasher, washing machine etc. and about 40- 60W export. On poor days like these the power going to the immersion from the proportional diverter can be as low as 10 or 20W and up to a maximum of say 300W yet the tank can still be up to a good temperature by tea time. A stepped system might not kick in until say 500 or 1000W and so would not provide any heat on days like these. On medium to good days my immersion thermostat will kick in by about 11am at this time of year but then that shouldn't be much different on a stepped system depending on the tank size etc.
The only drawback of a proportional system is the cost. The cost of parts to build mine was £170 but compared to a plumbed solar hot water system even the £300+ of a ready built proportional system seems cheap.
Reply to Solar Panel immersion heater automatic switch. in the Solar PV Forum | Solar Panels Forum area at ElectriciansForums.net
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