Can i power my immersion heater from my 4kw pv system?

[ihave4kw]

I have a question, basically can i heat my water using my immersion and the power from my 4kwpv system? I am trying to get the most benifit from my recent pv system install and think this is a good idea, any thoughts?

 

[Green]

Yes you can, there's various ways to do it depending on your inverter etc. The simplest way it could be done is with a timer switch on the heater, but if you get a really cloudy day it would end up importing energy to use the immersion.

Some inverters (SB4000-TL) can set up a multi function relay which could work for you.

 

[Scooby]

Yes, provided your 4kW is actually being delivered, which is won;t on overcast days. A typical immersion heater element is around 3kW rating, I believe, so anything produced by your panels will go towards this and save you money - on bright days it should easily supply everything that's required.

There's a thread on this forum about trying to automate this kind of system, using electronics to monitor the PV's output and switch on the immersion accordingly. There is also at least one make on inverter which has this feature built-in, tho' I don't know how it works exactly.

A simple manual method is to monitor the weather forecast and time the immersion to come on whenever your PV's output should be at its highest (eg: around noon on a south-facing system). Although crude, you just have to bear in mind that any output from your PV system - even 1kW - will go towards your water heating, with obvious savings.

 

[jeffsurvey]

Yes you can, go to *link removed* they will supply you with a replacement two element immersion heater (1kW & 2kW) and a switch that will turn on the mains to the 1kw element only when the inverter is producing 1.5kw's so will not effect the pv meter reading.

 

[Scooby]

That looks like a good solution, but a touch expensive? How much is it without the elements, Jeff? I could be interested in a similar system that could control a 1.8kW storage heater I have bought for charging via my PV system, so no need for the immersion elements (and I don't have stored water anyways!)

And also a shame about the wiring requirements - that will add further to the cost. Any option for a clip-on current sensor that'll take the generation readings?

.

 

[i=p/u]

ive seen other member talk about a 1kw heater

 

[powervan]

client of mine put in 1kw element!rec it works a treat!!

 

[moggy1968]

there is a monitor, which your installer can obtain from segen (amongst others I expect) which I beleiev glows one colour when you are in energy defecit and another when in energy credit. never used one but looks interesting. It's called a wattson universal display

 

[Scooby]

Yep - getting one of these! It still requires a manual output, of course - reaching out with your finger and flicking a switch when the energy is 'good'. I understand it can also be connected to a computer and download real-time readings - a bit of programming should allow it to control pretty much anything you want. If you really wanted to go that far.

 

[JohnBoyZ]

Hi, There is a lot of info about this subject on the Central Heating forum section, here is a link to the thread
http://www.electriciansforums.net/central-heating-systems/23969-immersion-heater-pv-electricity.html

Cheers
John

 

[stuart99]

A lot of DIY installers of such systems are running their 3Kw heater elements through a 110v site transformer. This is dropping the output to around 700w.

 

[stuart99]

Yes you can, go to www.parsonsswitch.com they will supply you with a replacement two element immersion heater (1kW & 2kW) and a switch that will turn on the mains to the 1kw element only when the inverter is producing 1.5kw's so will not effect the pv meter reading.

Just had a look at that and like most solutions has the same problem, its only monitoring the output of the solar and then switching on at say 1.5kW. What it is not taking into account is the load currently being run in the house - so if you have the washing machine and dishwasher on, you could already be drawing over 1kW. The Parson Switch will not know this so blindly switches on the hot water as well - and you end up paying to IMPORT from the grid :stuart:

A lot of people don't realise that most of the newer SMA TL inverters already have a switch relay built into them which would operate exactly the same as the Parson Switch (might need some other external relays to operate the immersion).

 

[Dw911]

I cannot suggest you any better option than to visit this site www.snhtradecentre.co.uk. Thwy will deliver the demanded information.

How does a link to a site selling over priced taps and fires help the Op with his immersion heater issue ?

 

[SPARTYKUS]

Hi Ihave4kW,

might seem like a daft thing to say but we have solar-heated water - which admittedly does not work when the sun ain't shining (but neither will your immersion, well, not the one fitted at moment anyway).

It works great. for months and months of the year we do not use any gas or elec to heat the water. It saves alot of money. Our system was put in in the early days so possibly has a few too many panels but still, worth considering?

Cheers

S.

 

[Richard]

Would it be feasible to use a non grid ties solar PV system to solely heat a large heat store? This is something I have been thinking about for a while. Even if the inverter was only supplying a 3KW element with say 500W AC, am I correct in thinking that the water would still heat, albiet at a slow rate?

Thank you

Rich