Immersion and Solar

[lewisericeric]

I'm sure this has probably been done somewhere already but I can't find it!

 

Basically, my panels are going into float mode after charging the batteries easily by 11.30AM- 1PM and it seems a waste not to have the panels being used during the rest of the day - I can either get more batteries or try and hook the panels up to the immersion. I'd rather go with hooking up to the immersion.

 

I've seen this online (second pic down) http://edwardsnb.blogspot.co.uk/2013/04/immersion-heaters-and-solar-panels.html

 

Full details of it here: http://www.altestore.com/store/Charge-Controllers/Dump-Loads-Dump-Load-Controllers/Diversion-LoadsDump-Loads/Water-Heating-Element-for-12V-or-24V-DC/p2326/

 

It's basically a 12v immersion heater....

 

However, I don't really know how it would be set up to the solar panels. I presume it needs to run via the MPPT controller still? ( just for info I have an Outback FlexMax 80 )

 

Does it need to be fused etc. and also would this fit with the calorifiers we have on boats. I have one of the blue case calorifiers, only a couple of years old from Midland with the 240v immersion on top.

 

Anyone in the know how about this sort of thing. Just to add - Im not botherd about opinions on whether its worth it or not - i may as well add it even if it gives just a bit of warmth to the water, its better than having the panels just in float and doing not a lot!

[Chris Pink]

Fuse yes.

 

I think it would have to be switched I don't think the outback does load diversion.

 

There's no need to be so grumpy.

 

Eta; looks like you can do load diversion

 

According to the heater specs although they are wrong about the Morningstar units they can't do load diversion so I would check your outback manual first.

[Theo]

Incidentally, having extra batteries would not serve your purpose. Frexample if you use 100Ah each day then you need to replace just that. Having lots of capacity will make no difference to the amount of charge that you need to replace it.

 

Nick

[smileypete]

What's the voltage of your array at maximum power point?

 

If it's say 100V then connecting it directly to a 240V 3kW immersion will give ~500W.

 

Might work out OK and be a bit cheaper than a 12V immersion.

 

cheers, Pete.

~smpt~

Edited April 22, 2013 by smileypete

[lewisericeric]

Exactly Nick - that's why adding batteries is something I'm not considering - there's just no point especially when they're a consumable etc.

 

Chris - ill check my outback manual and maybe it will give me some wiring info there too. I suppose that's my biggest query really - how to basically wire the solar panels to the immersion heater? I never grumpy

 

Also, is knowing if that element will fit these boat calorifiers.

 

Smileypete - I think each panel is 30v roughly. And I have 690w of solar.

 

ETA - just seen your edit smileypete. I have 3 panels rated at 230w and I think like I say they are 30v each.... I currently have a 1kw immersion fitted.

 

It's how I would wire it up though that's the difficult part for me to understand?

[matty40s]

Two wires.:..

 

 

 

 

Don't get grumpy

[lewisericeric]

Two wires how?!? Now I am grumpy!!!

[Grace and Favour]

Two wires how?!? Now I am grumpy!!!

Neg to Neg

Pos to Pos

 

 

 

 

[lewisericeric]

But it's not wired to the battery is it????? It needs wiring to the solar or the MPPT.

[Paul C]

around 3 minutes in, explains how this particular device (Blue Sky SB3024i /iL) can do what the original post suggests. It has a separate terminal for its 'load control' output.

 

PS A bit more reading shows that this is a $75 option (a software upgrade) which is done by removing, then installing a new chip into the controller. The manual for the "DUO-option" is here:

 

http://www.blueskyenergyinc.com/uploads/pdf/Manual_Addendum_BSE_SB3024_DUO.pdf

Edited April 22, 2013 by Paul C

[peterboat]

Hi I have a 12 volt 300 watt immersion heater in my calorifier it runs off 2 independant solar panels through a 12 volt regulator the instructions are very explicit about the immersion not being a dump load also it cannot be connected to a battery. I chose a an immersion that fitted into the calorifier they had various sizes so it was no problem. On reflection I should have stuck to the 240 volt 1 kilo watt that was originally fitted and used it as a dump load as my system too idles from lunch time onwards on sunny days hope this helps

 

Peter

[lewisericeric]

Thanks for the links Paul I will have a look into them

 

Peter- I have a 12v 1kw immersion. I guessing then the product that Paul has suggested is connected to the batts and the. That regulates/sends any excess power to the immersion? Am I on the right lines here.

 

Bit of a dummy when it comes to the technicalities of it all!

 

So it looks for ease and for what I've got I should use my immersion as a dump load and forget about changing the immersion for a 12v one?

[DeanS]

I have a solution.

Moor up next to us, and share some of your solar. ?

 

TaDaaaa!

[lewisericeric]

Gladly dean! But you'd have to come here (somehow!) we love this place too much and couldn't go back!

[peterboat]

Hi yes I am thinking of going back to the 240 v immersion as I suspect half a day of more watts is worth more than a constant 200 - 300 watts. It does work but if I put the other 2 panels back into the system I will do much better who knows

 

Peter

[blodger]

Just wondering if a voltage relay would be any good to connect either from the battery or the controller load function to a 12v immersion element. Perhaps a timer could be incorporated so that it does not look at connecting till noon.

I have often wondered whether say a 600w inverter in the line to a 240v ac immersion element would convert whatever 12v nominal power is put into the 'load' circuit to warming/heating the water.

 

ETA I presume VSRs are available at different connecting voltages, 13.8v up. I have seen them on EBay at 30 quiddish. Also I have a 1kw element and was considering feeding this through a 110v transformer to derate it to 500. I suppose there are lots of options but the fact there is little reporting of it having been done successfully, ie worth the cost/effort means its a bit 'pie in the sky'

Edited April 23, 2013 by blodger

[smileypete]

But it's not wired to the battery is it????? It needs wiring to the solar or the MPPT.

Are your panels in series? If so you should get about 90V which will give 140W when connected to a 240V 1kW immersion. Also how's the immersion connected? If it plugs in then just unplug and connect the solar array to the 'L' and 'N' pins on the plug with croc clips. But if the immersion is permanently wired in to the boats mains then best leave alone.

 

Maybe a better way would to leave the inverter on then use a timer to control the immersion, have the timer come on for short periods late morning and early afternoon.

 

Something else is that lukewarm water sitting around for long periods is a risk factor, albeit very small, for legionalla. The water needs heating to 60°C for a while before use really.

 

cheers, Pete.

~smpt~

Edited April 23, 2013 by smileypete

[ditchcrawler]

Are your panels in series? If so you should get about 90V which will give 140W when connected to a 240V 1kW immersion. Also how's the immersion connected? If it plugs in then just unplug and connect the solar array to the 'L' and 'N' pins on the plug with croc clips. But if the immersion is permanently wired in to the boats mains then best leave alone.

 

Maybe a better way would to leave the inverter on then use a timer to control the immersion, have the timer come on for short periods late morning and early afternoon.

 

Something else is that lukewarm water sitting around for long periods is a risk factor, albeit very small, for legionalla. The water needs heating to 60°C for a while before use really.

 

cheers, Pete.

~smpt~

I wonder how many cases of legionalla have be caused by this?

[Paul C]

I wonder how many cases of legionalla have be caused by this?

 

It depends if you regularly drink from the hot water tap (tank). Yes, the heating profile for the hot water is slower than eg a 3kW immersion element or running, the engine for 8 hours cruising, but there's plenty of other comparable scenarios. For example running the engine or cruising for a shorter period of time.

[Arthur Brown]

I suspect that ALL the legionela problems involve slightly warm water. In solar water heating systems the solar is a prewarm and then there MUST be a real heater to produce 60+C and hold the water there for a while to heat sanitise it. IIRC someone on this forum had legionaires disease from stagnant water in the shower pipes. The infection is usually transmitted in water spray being taken into the lungs so splash from a shower or tap is a prime infection route.

[peterboat]

Bugger! I am never going in the shower again!! No seriously I use my warm water for washing in and washing down surfaces etc the water I drink is from a filter on the cold system and all crockery etc is done by dishwasher. I mostly get showered at the gym so I should be safe but thanks for the warning

 

Peter

[onionbargee]

would solar voltaic really be worth bothering with to heat water ? iv'e never heard of it, but i'm not well versed on solar.

 

isn't a solar water heating panel designed for that ?

[Paul C]

would solar voltaic really be worth bothering with to heat water ? iv'e never heard of it, but i'm not well versed on solar.

 

isn't a solar water heating panel designed for that ?

 

I wouldn't fancy the plumbing requred to-from a solar water heating panel. (Others might). At least with a solar panel (the electric kind) there's just wires.

[Chris Pink]

Which makes one wonder; how does electricity run uphill?

[Jambo]

would solar voltaic really be worth bothering with to heat water ? iv'e never heard of it, but i'm not well versed on solar.

 

isn't a solar water heating panel designed for that ?

 

It's much more efficient to use a proper solar water heating panel. They convert something like 60% of the energy falling on the panel to useful heat whereas a PV panel will only convert about 15% to electricity.

 

But when you have limited battery capacity, there's a lot to be said for making use of your PV panels when the batteries are full. If it's quite simple to dump that excess capacity into water heating then it's worth looking at.

 

I'm trying to work out whether it's easier to install a small solar water heating panel or to go for PV dumping. Can't work out what's easiest yet.