Mixing Solar with SHoreline

[Keajre]

Greeting Wonderful Boating Friends,

 

I had a thought.  I've had my 250w panel and MPPT for a few years now (with 600Ah of batteries and an inverter).  It only usually gets used properly when I am continual cruising in the summer months. When I am connected up to ShoreLine power the panel isnt used since the MPPT detects the batteries are full. 

 

Anyone know of a device or a method so that you could switch seamlessly between Solar and ShoreLine power so as NOT to use any grid power unless solar was at capacity or beyond?  

 

Say for example you are drawing 300 watts.  A usual scenario for me when working from home with laptop and monitor on.  The inverter has to power these items (either inverting or pass through when connected to grid) since they are 240 (most of other items are 12v).  Wouldn't it be great if say it was a sunny day, and the panel was capable of pulling in 200w, that ONLY the additional 100 watts would then be supplied by grid.  Would reduce the electric bill and carbon footprint.

 

I dont know of a way to do this without disconnecting shore on sunny days and inverting.  That's a bit of a lame solution though for several reasons.

 

Any thoughts?

 

[Alan de Enfield]

8 minutes ago, Keajre said:

Greeting Wonderful Boating Friends,

 

I had a thought.  I've had my 250w panel and MPPT for a few years now (with 600Ah of batteries and an inverter).  It only usually gets used properly when I am continual cruising in the summer months. When I am connected up to ShoreLine power the panel isnt used since the MPPT detects the batteries are full. 

 

Anyone know of a device or a method so that you could switch seamlessly between Solar and ShoreLine power so as NOT to use any grid power unless solar was at capacity or beyond?  

 

Say for example you are drawing 300 watts.  A usual scenario for me when working from home with laptop and monitor on.  The inverter has to power these items (either inverting or pass through when connected to grid) since they are 240 (most of other items are 12v).  Wouldn't it be great if say it was a sunny day, and the panel was capable of pulling in 200w, that ONLY the additional 100 watts would then be supplied by grid.  Would reduce the electric bill and carbon footprint.

 

I dont know of a way to do this without disconnecting shore on sunny days and inverting.  That's a bit of a lame solution though for several reasons.

 

Any thoughts?

 

Switch your battery charger off and use the mains to power your 240v appliances

Switch the inverter off

 

Let the solar keep charging your batteries for powering all the 12v appliances.

 

Doesn't really achieve what you want but it does let your solar work to capacity.

[Keajre]

5 minutes ago, Alan de Enfield said:

Switch your battery charger off and use the mains to power your 240v appliances

Switch the inverter off

 

Let the solar keep charging your batteries for powering all the 12v appliances.

 

Doesn't really achieve what you want but it does let your solar work to capacity.

Hmm ye that would be slightly better, I suppose then at least the pump, fridge and lights would be powered by solar.  Not a bad idea.  Didnt think of that, will try it ?

[Robbo]

Set the voltage of the mains charger slightly lower than the solar charger and run your mains stuff from the inverter.   So the only thing shore power is powering is the mains charger and as the solar charge voltage is slightly higher then it should use this first.

Edited September 24, 2018 by Robbo

[Jen-in-Wellies]

I have a switch inside the cabin that can be used to disconnect the shore line input into the inverter/charger during the day if it looks to be sunny. Got in to the habit of turning it back on in the evening for the charger to fully charge up the batts overnight. There are plenty of timers that can automate this. For example - https://www.screwfix.com/p/greenbrook-mechanical-timer-230v/4883r. 

 

Some Victron kit plays nice with solar and can prioritise it over shore line when available I believe. Some can be programmed to do so. Not looked in to this closely.

 

Jen

[Detling]

Remember battery life is measured by cycles, discharging the batteries when shorepower is available is just bringing forward the day you need new batteries. If you have massive solar, in summer just unplug on sunny days, as the solar will keep the batteries full but plug back in before 5pm or when it clouds over.  In winter it is unlikely the solar will generate enough to make it worth while.