Home-automation to control fan heater based on solar PV output?

celerity

Does anyone know of a product that allows a plug socket to be controlled via the web?

I have solar PV, and have realised that on several winter days I have over 2000W of "spare" energy to use. I would like to take advantage of this by turning on a fan heater to warm my office up.

However, as has been discussed many times on here, solar is not reliable enough to do this on a simple timer basis, an automated solution needs to be a lot smarter.

I have rigged the output data for my panels to the web, as well as room temperature, and would like to use this data to control the fan heater.

The idea would be that I'd write a script along the lines of:

if (temperature-of-room < 19C AND solar-output > 2000W) then Turn On Heater.

I don't have any home automation experience though, so don't really know what is readily available to me.

I suppose I'm really after a plug socket which either connects to my router wirelessly or via ethernet, and also runs its own webserver and a simple API to turn the switch on or off.

Alternatively, a similar product but which works by USB and an easy to use driver, which I could plug into a lowcost Linux "plug" computer.

Or, alternatively again, use a Linux plug computer, but skip the web and just connect it directly to my Sunny Beam. The slight disadvantage of this is that the Sunnybeam doesn't give temperature data, so I'd need to get a separate USB temperature sensor.

The point being I don't want to have any of my main computers running in order to operate the heater, I want something with a low power footprint.

To give an idea of my skillset, I'm a web programmer and am happy to write web services, configure Linux etc. What I wouldn't be comfortable doing would be to use an Arduino chip or similar.

Any advice appreciated,

/\dam

penrhyn

Sounds an overcomplicated solution, what about something like this?

http://www.livefoods.co.uk/product_info.php/habistat-sun-switch-day-p-493

HappyMJ

celerity wrote: »

if (temperature-of-room < 19C AND solar-output > 2000W) then Turn On Heater.

The problem with that is the temperature will be the opposite of the solar gain on the property. The higher the solar gain the higher the temperature on the house. If it's cold then the solar panels will not be producing 2000W of "free" electricity so it will never trigger.

Really the only thing you should be considering timing is the washing machine in the middle of a summers day.

Cardew

Assuming you have gas CH, 2kW(spare) electrical capacity will save approx 6p to 8p an hour.

Drop that spare capacity to 1kW and you will be losing money.

How much woul you save in an average UK winter - £5?

celerity

Thanks for the responses everyone,

@penrhyn : that wouldn't be accurate enough to work, I'd only want the switch to activate when my panels were producing above a set figure, not just when a cheap light sensor was activated. Also, the output on the device you linked to is only 600W, whereas my fan heater pulls about 1kW.

@HappyMJ : I don't really understand your response I'm afraid. First of all, the temperature sensor is inside, not outside. Secondly, low temperatures do not result in low solar PV output. On the contrary, provided the sun is shining, low temperatures result in a significant boost in output as the panels run more efficiently when cool.

@Cardew, I'm on oil, not gas, sadly! I'm going to be buying a plug PC anyway for various projects, so that cost shouldn't be factored in. It's really just the "smart" socket I'd have to buy for this, and I have no idea how much they cost, or what is available, hence this thread.

/\dam

HappyMJ

celerity wrote: »

@HappyMJ : I don't really understand your response I'm afraid. First of all, the temperature sensor is inside, not outside. Secondly, low temperatures do not result in low solar PV output. On the contrary, provided the sun is shining, low temperatures result in a significant boost in output as the panels run more efficiently when cool.

On a sunny day in winter the property heats up due to the sun shining through the windows. It might be cold outside but it radiates heat inside and heats up naturally. It's called solar gain. A 2000W load would mean you would be need to be generating about 8kWh in a day if the sun was shining for 4 hours. In winter that's highly unlikely. It might work with a little 600W mini oil filled radiator but not a 2000W load. Heaters and solar panels just don't go well together.

larkim

Not if the room you are in is at the back of the house though. Obviously, keeping the right doors open etc etc helps, but in some houses a dark cold room is a dark cold room no matter what you try.

whasup

My suggestion is do a list of all the items that cost you money and all the possibilities for reducing that outgoing. Listed in order of priority, cost effectiveness and potential return I'd bet developing an automated fan heater will be way, way, way down the list.

celerity

HappyMJ wrote: »

On a sunny day in winter the property heats up due to the sun shining through the windows. It might be cold outside but it radiates heat inside and heats up naturally. It's called solar gain. A 2000W load would mean you would be need to be generating about 8kWh in a day if the sun was shining for 4 hours. In winter that's highly unlikely. It might work with a little 600W mini oil filled radiator but not a 2000W load. Heaters and solar panels just don't go well together.

OK, I think you are saying a) my switch would never trigger and b) when it did I'd end up losing money anyway.

First of all, it's not a 2000W load, my fan heater draws about 1000W, measured by pugging it into an energy meter.
Secondly, I honestly don't see the relevance of solar gain in the house - my office simply does not warm up significantly in the winter, even when it is sunny. Certainly not up to 19C anyway, which is the temperature I like it to be.

The situation is that my panels have already regularly been pumping out more 1.5kW more than I am using to run my office during November, and for hours at a time. I would like to use this energy in an automated way, so I don't have to bother micro-managing it.

Cheers,

/\dam

celerity

larkim wrote: »

Not if the room you are in is at the back of the house though. Obviously, keeping the right doors open etc etc helps, but in some houses a dark cold room is a dark cold room no matter what you try.

It's not just cold, it's really badly insulated .

I've put 30cm insulation in the loft, but can't cavity wall because the builders filled the cavity with 1cm of polystyrene sheet, which is of course useless for insulation, but does prevent any other proper filler being put in (three cavity wall surveyors have confiemed this).

External cladding isn't a great option due to one inaccessible wall and so many windows that it wouldn't make much difference.

I don't really fancy internal cladding either, as it will make the room a bit smaller and be massively disruptive to my work (all the furniture would need to be moved, the room redecorated etc).

The windows are double glazed but are a bit old. I don't have the budget to replace them with decent ones, especially as given the cold walls this may not help as much as it could. I have sealed up the ventilation holes above them though!

A plumber is about to zone the rad in here, so we can heat it independently of our house, that will help.

I'm seriously considering asking a builder for a quote to brick up an external door and window that aren't needed, but don't know how much good that would do.

We have installed a wood burner, which is great. But it does take several hours to get the room up to temperature.

In practise, what I'll probably end up doing is using the oil-fired rad in the morning and the wood burner in the afternoon.

Really, this thread is just speculating on how I can use free electricity to help out these two primary forms of heating.

/\dam

zeupater

Hi

Go and pick a £30 low power electric oil panel radiatior from te5co (currently £20) 400/600/1100W and try it out manually besides where you're sitting and see what benefit it gives when switching manually .... you'll need an OWL (or similar) and a SunnyBeam (or similar) in front of you to achieve this .... if you see a benefit and your fingers don't wear down to stumps then find a way of automating the switching (x10/Bluetooth Inverter script/OWL USB (http://www.uk-automation.co.uk/products/Owl-USB-Connect-%252d-USB-energy-monitoring.html))... if it doesn't work out then you'll have some more junk for the back of the garage ... but it'll have only cost £20-£30.

ps ... if you get all of the scripting sorted and can run this from a reliable low cost tablet pc then it might be useful to others ....

Easier way if you have a SB4000TL inverter would be to have the inverter switch a relay if the production is >X and have a room thermostat switch a second relay depending on temperature ... total cost is wire, thermostat, a couple of relays and an electrician for a couple of hours (which could equate to a couple of pints if you know a friendly one who likes to play ! :cool:) ..... the only problem is that the automatic relay could be switched on at the same time as the kettle or washing machine

HTH
Z