Cruisers Forum
 


Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 14-04-2021, 07:18   #1
Registered User
 
SaltyDogsLLC's Avatar

Join Date: Feb 2017
Location: St Simons and the Abacos
Boat: FP LUCIA 40, Hull #51
Posts: 34
Water Heater switching while on Solar - Victron System

Victron System, Multiplus Compact 12V/2000VA/80A, MPPT 100/50 Solar, Cerbo GX with touchscreen controller. I believe I can use those Cerbo GX relay outputs to switch the water heater on and off based on battery state.

I looked on another thread that discussed doing this, so my question is more about would you be inclined to use a 300W 12VDC heating element or what is currently in my water heater (AC powered, have to see what the wattage is)? I guess the downside is that the AC element requires the inverter to be on, but it's on anyway since it powers outlets on boat. My research shows the DC element is not quite as aggressive in heating the water as AC.

I'm not opposed to running the genset each day, but you know how sailors can be (the wind is free, shouldn't everything be?)...since we have solar and wind turbine, I thought I could maybe snatch some heating energy from them. We have 760 W of solar, only 400 AH battery capacity on house bank. Thanks for your comments and suggestions.

If you've done this already, I'd really love a quick diagram/schematic of what you've done!

Enjoy the day
__________________
Escape Plan
Lucia 40
www.svescaeplan.com
SaltyDogsLLC is offline   Reply With Quote
Old 14-04-2021, 10:07   #2
Registered User
 
chris mac's Avatar

Join Date: May 2015
Location: edmonton alberta
Boat: 1992 lagoon 42 tpi
Posts: 1,211
Re: Water Heater switching while on Solar - Victron System

I just switched out my element. It was 110v, 1500 watt. Which is a 125 amp draw at 12 v. That's a pretty heavy draw against golf cart batteries(which is what I have)
I installed a 12v 300 watt element. That is only a 25 amp draw. Which means the solar panels are able to replace the power as it's being used and isnt hurting the batteries.
The downside of course is needing to run the heater for 5 times as long to get the same temp increase.
For our 11 gallon tank, 3 hours seems to get it hot enough that we need to mix cold in for a shower. Here in the Bahamas, I'm able to run it 3 hours per day and still have full batteries at sunset.
I have 640 watts of solar, and 840 AH battery bank.
I am looking at increasing solar and getting the victron monitor as well.
chris mac is offline   Reply With Quote
Old 14-04-2021, 14:19   #3
Registered User
 
SaltyDogsLLC's Avatar

Join Date: Feb 2017
Location: St Simons and the Abacos
Boat: FP LUCIA 40, Hull #51
Posts: 34
Re: Water Heater switching while on Solar - Victron System

Thanks Chris - is the water heater on full time, or switched?
__________________
Escape Plan
Lucia 40
www.svescaeplan.com
SaltyDogsLLC is offline   Reply With Quote
Old 14-04-2021, 15:13   #4
Registered User
 
chris mac's Avatar

Join Date: May 2015
Location: edmonton alberta
Boat: 1992 lagoon 42 tpi
Posts: 1,211
Re: Water Heater switching while on Solar - Victron System

Quote:
Originally Posted by SaltyDogsLLC View Post
Thanks Chris - is the water heater on full time, or switched?
I ran it to the breaker panel. So I manually turn it on and off.
chris mac is offline   Reply With Quote
Old 15-04-2021, 02:57   #5
Registered User
 
JustMurph's Avatar

Join Date: Aug 2020
Location: Brisbane, QLD, Australia
Boat: Mumby 48
Posts: 43
Re: Water Heater switching while on Solar - Victron System

If there is a 12V option, I'd go for that in your case. I have a 240V 750W water heater and use my Cerbo GX to control it so that it runs on excess solar (1.7kW system).

Happy to offer some advice on configuring the Cerbo GX to do that.
JustMurph is offline   Reply With Quote
Old 15-04-2021, 03:55   #6
Registered User

Join Date: Aug 2010
Location: Oz
Boat: EX prawn trawler 14m
Posts: 123
Re: Water Heater switching while on Solar - Victron System

Just want to share some information on what is working for me.
At home 3x 270w panels in series with a 4500w 240v element, increase of 10 deg per day in 400 ltr system. Controlled by digital thermostat. That's DC to AC element direct. Backup element in the top of the tank set to 60 deg and connected to the grid. This setup maintains temperature even during a string of rainy days, solar panels still work better on rainy days than thermal heating panels do. My backup element hasn't used one bit of power during 5 continuous rainy days.

In the caravan 300w 240v element run off 1 K 12/240 inverter same digital thermostat. Mostly have turned on when tug is running so alternator handles the load and have hot water when we pull up. Caravans 320w solar handles this pretty well also including other loads while we are anchored up, although I limit the time I have it turned on. I see an increase in temperature of about 2 to 3 deg per hour in an 11ltr tank. No problems getting to 45deg which is what our temperance valve is set to.

Haven't bothered on the boat as it's a stink boat and don't have them white sheets and poles, so we have to run the engine anytime we move. Heat exchanger has HW system up to 80deg within 15 minutes. Then the Genset cranks the 240v element anytime we are anchored. Over 1k of solar on the roof but haven't found the need to go down that road.

Hope this helps someone.
Cheers Dave
redog is offline   Reply With Quote
Reply

Tags
heater, solar, water

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Switching from Cockpit to Cabin Top Mainsheet System sailscubasurf Deck hardware: Rigging, Sails & Hoisting 2 29-01-2017 21:21
Switching to fresh water flush question SausalitoDave Plumbing Systems and Fixtures 29 03-08-2016 14:26
Solar Controller Automatic Series/Parallel switching zboss Marine Electronics 3 02-08-2014 10:43
Gas Water Heater or Combined Calorifier / Immersion Heater ? simonmd Plumbing Systems and Fixtures 5 30-12-2010 08:50
Switching batteries while engine running hns1934 Electrical: Batteries, Generators & Solar 7 28-09-2008 20:47

Advertise Here


All times are GMT -7. The time now is 15:44.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2021, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.