A Pv Question..... Dont Laugh

[the doctor]

Hello All,

I was talking to my uncle the other day.... ( he is an electrician too) and he asked me something that I have been mulling over.

If you connected a 3kW pv direct to say an old storage heater, would it charge it up and work. He says that the inverter is the expensive bit and heating is also an expensive bit so why not kill two birds with the one stone... Sort of got me thinking of the old electricair 10kW central storage unit with ducted heating connected to a big pv on the roof....

Too start this thread, I am stating that yes, dc would probably ruin the small switch contacts in stats and so on.

He also said tonight, "Why cant you connect a 3kW pv straight to an immersion element" Again a way of 'storing' the energy if you like...without an inverter...

Cheers,

Alan

 

[binky]

Can't think of any particular reason why this wouldn't work. Inverters are much cheaper if not G83 gid tied units - have a look at charge controllers. Downside of this idea, is that summertime when PV works best, is also the time you don't need heating, so as this is a dedicated system,you're a bit stuffed for a suitable use for the leccy, unless you have a swimming pool? (Standard tank of water would not use enough leccy to match PV production)

 

[sellers]

Yes, but the inverter needs 240v to work. So what you would have is a storage heater thats on all the time and only free when the PV's up and running. You may be able to fashion something using a photocell.

 

[ProDave]

Actually it sounds to me like he's planning to connect the DC string of inverters straight to a heating element WITHOUT the "expensive bit" the inverter.

It probably will work, but it will not be particularly efficient, and you will have to select the number and type of panels to give a voltage of close to 240V

What's the motivation for doing this, rather than a proper system on the FIT that pays you money, and you can still use a dump controller to heat some free hot water

 

[binky]

the idea does miss the obvious point as highlighted by Pro Dave, the FiT pays for the system, and makes a profit, so why worry about inverters - now down to £600, and being legal, cos it might cost a few quid. A full 4 Kwp system is less than £6500 using decent gear, you can run immersion via Immersun gadget at £300+vat, and the fact is ROI stands at around 12% - get that off a bank account if you can :slap .

 

[the doctor]

Hi

Thanks for the replies...

I was at a house today and the customer has one of these...

http://www.immersun.co.uk/

It is a clever little box that scraps the export of spare energy and sends it to an immersion element. Far better value than exporting the juice for half price.

He had just ripped out his electric shower and fitted a second mixer shower fed off the tank.

 

[ProDave]

The good bit about the immersun and other things like it, is you STILL get paid the "deemed export" sum as well as using all yur surplus electricity.