Solar Dump tiny cabin

[sun85]

Hi There,

I have a Renogy Rover 40a MPPT controller charging 880a Lead acid batteries, with 700w of Renogy Solar panels.

Is there a way to wire in a Water Heater "dump load" to make use of excess solar?

if so what do i need to add or how do i change the settings if possible on the controller?

sorry im very new to all this, thanks in advance.

 

[SamDeleted]

Hi sun it is possible by adding morningstar Tristar PWM to your system, takes a bit of setting up & learning, I'm not 100% sure on it myself

Installing and configuring a Tristar controller for a wind system | Hugh Piggott's blog

 

[SamDeleted]

MorningStar Tristar Three-function PWM controller

Buy MorningStar Tristar Three-function PWM controller For Sailing Boats & Yachts, with Free Delivery to the UK. For use with solar electrical systems and as a diverter for excess energy to a dump source. These powerful tropicalised three-function PWM controllers provide reliable solar battery...

www.promarinestore.co.uk

Doesn't come cheap I'm afraid

There may be other option though I am not sure

 

[OzSolar]

Hello and welcome to the forum!

There's a few threads about using excess PV to heat water but first we should talk a bit about your solar to battery ratio.

FWIW, from experience, I'll caution you might struggle to properly charge your batteries.

Generally speaking lead acid batteries in a cyclic application will do best with when they see amp of at least 10% of thier AH rating for charging. 880 AH x 10% = ~90 amps of charging.

What voltage is your system? How many batteries?

 

[sun85]

Hello and welcome to the forum!

There's a few threads about using excess PV to heat water but first we should talk a bit about your solar to battery ratio.

FWIW, from experience, I'll caution you might struggle to properly charge your batteries.

Generally speaking lead acid batteries in a cyclic application will do best with when they see amp of at least 10% of thier AH rating for charging. 880 AH x 10% = ~90 amps of charging.

What voltage is your system? How many batteries?

They are 110ah leisure batteries currently running 8 of them in parallel, and at 12v, im only running them down to 50% for obvious reasons.

system is powering a 80w wine cooler and 50w of fish pond equipment 24-7

I've aso wired in a Renogy 30a PWM which is controlling 300w of the system as all together it would be to much for my 1 MPPT controller

thank you for everyones replies

 

[SamDeleted]

They are 110ah leisure batteries currently running 8 of them in parallel, and at 12v, im only running them down to 50% for obvious reasons.

system is powering a 80w wine cooler and 50w of fish pond equipment 24-7

I've aso wired in a Renogy 30a PWM which is controlling 300w of the system as all together it would be to much for my 1 MPPT controller

thank you for everyones replies

Hey sun85 out of interest , how are your 8 leisure batteries wired up ?

Are they all being drawn on / charged equally?

 

[sun85]

Hey sun85 out of interest , how are your 8 leisure batteries wired up ?

Are they all being drawn on / charged equally?

Hi Sam,

One controller is wired, battery 1 positive closest, and negative on battery 8

The other controller wired, positive on battery 8 and negative on battery 1

 

[SamDeleted]

Hi Sam,

One controller is wired, battery 1 positive closest, and negative on battery 8

The other controller wired, positive on battery 8 and negative on battery 1

Ah I see . you've got it right to do it diagonally. 8 batteries is a lot of in parallel so always worth keeping an eye on the balance

Only one thing is , ALL connections to the battery bank should be made at the same two corners, not mix and match

SCC
Inverters
Mains charger
DC loads

everything , lugs stacked on battery 1's pos & battery 8's neg


Worth a read if you're interested:

SmartGauge Electronics - Interconnecting multiple batteries to form one larger bank

 

[sun85]

Has anyone used this ? i have a Water butt and was thinking about the element, Controller and possibly the relay

12V Water Heater 300W 1 Inch BSP screw in element - dump load

www.bimblesolar.com

12V 24V Digital Voltage Sensing Relay 10A - battery protection -- dump load -- auto switch battery banks

www.bimblesolar.com

12V 200A Split Charge Relay - Charge 2 batteries from alternator or for Dump Load - Outback Aux

www.bimblesolar.com

Wiring here:

https://www.bimblesolar.com/docs/digital-relay-E1200.pdf

 

[SamDeleted]

Has anyone used this ? i have a Water butt and was thinking about the element, Controller and possibly the relay

12V Water Heater 300W 1 Inch BSP screw in element - dump load

www.bimblesolar.com

12V 24V Digital Voltage Sensing Relay 10A - battery protection -- dump load -- auto switch battery banks

www.bimblesolar.com

12V 200A Split Charge Relay - Charge 2 batteries from alternator or for Dump Load - Outback Aux

www.bimblesolar.com

Wiring here:

https://www.bimblesolar.com/docs/digital-relay-E1200.pdf

I haven't personally, looks like a good cheap solution


Have a chat with bimble, they are nice people should be able to set you straight


If you get it working pls come back and share I'd be interested

 

[12VoltInstalls]

Ah I see . you've got it right to do it diagonally. 8 batteries is a lot of in parallel so always worth keeping an eye on the balance

How they are paralleled is important.

When I was running 8 fla’s I drew out a bunch of “options” that were possible.
In the end, 16 equal length cables or “4Px2” were the only practical way it made sense.
“Daisy chain” style arrangements leave the batteries in the middle neglected. And 800W isn’t quite enough to keep them healthy.