Need advice powering immersible heaters with solar!

[janx221]

Hi there!

I have 3.8kw worth of panels ( 10x 380w 48v) and my house has central heating system powered by wood burning stove.

Is it possible to install for example 2x 1500w 48v dc immersible heaters into the tank and directly connect them to the panels for a little extra heat and maybe reduce the amount of wood needed to burn? Is this kind of system safe? Another option would be connecting the panels such that the output voltage is 240v and then getting 240vdc immersible heaters.. is there some difference? Can AC water heaters work with DC volatge from panels ?

Any advice and suggestions are welcome or just tell me is a bad idea

Thanks in advance!

 

[mopat]

Is it possible to install for example 2x 1500w 48v dc immersible heaters into the tank and directly connect them to the panels for a little extra heat and maybe reduce the amount of wood needed to burn? Is this kind of system safe? Another option would be connecting the panels such that the output voltage is 240v and then getting 240vdc immersible heaters.. is there some difference? Can AC water heaters work with DC volatge from panels ?

Yes.
Yes.
Difference, not really.
Yes.

 

[OzSolar]

Welcome to the forum!

Any advice and suggestions are welcome or just tell me is a bad idea

It's a great idea but it's hard to pull off in practice. In my experience, all active solar space heating systems eventually get abandoned. It's a fundamental challenge as the peak demand is opposite the peak resource. Short days and long nights.

You'll save more by using you PV to make electricity for your home year around than dedicating it to space heating.

Do a little digging around the forum. There's several threads on this subject. You'll see that you've got to carefully match the voltage of your solar to the electric elements (ohms law) plus switching high voltage DC requires some special components not readily available. There's quite a bit more going on than just hooking them up.

My family lives in passive solar home that I designed and built myself. Honestly it wasn't that hard. If it's sunny and warmer than 10f we don't need any supplemental heat in the day time. Depending on how sunny it was in the day and how cold it is during the night we rarely need supplemental heat until a few hours before sunrise and honestly we could make it if we were willing to wait until the sun started warming up the house again.

 

[cotswoldstony]

Hi, pv solar water heating works well in the summer months using dump load for free hot water especially on small capacity water tanks and you have a good solar array to do this. This will not work well in the winter months in the UK so I would suggest fitting a heat exchanger coil around the wood stove pipe and into the central heating system this will lower your wood consumption. I did this in my workshop on a waste oil heater and ran radiators around the walls for a free central heating system for many years. The heat exchanger coil you make must be 6 or 8mm copper pipe according to the temperature output from the stove pipe at medium Kw/Btu output rating of the wood burner to keep radiators hot with low wood consumption.