Cool idea: fridge powered entirely by solar panels, no battery use

[john61ct]

https://joeyh.name/blog/entry/fridge_0.1/
https://joeyh.name/blog/entry/fridge_0.2/
https://fridge0.branchable.com

Similar idea, but separate https://www.ice-energy.com

[newhaul]

Rich builds systems just like this for remote off grid situations . Not just for boats.
CoolBlue Overview

[OzePete]

Ozefridge manufacture real hold-over systems with 'Sure-thaw' control that require as little as one run cycle per 24 hours. The built-in ECO2 power management causes this daily run cycle to occur once the voltage reaches 13.5VDC and therefore abundant (otherwise wasted) power is used... NO battery drain!

Click on data to enlarge...


The above chart is of a typical 100 litre (4+ CF) top opening fridge with 75mm of urethane insulation, maintaining a cabinet temperature of 2 to 4C in a 30C environment. Note the bottom window indicates sufficient daily (24hr) refrigeration is provided by one 3.25 hour run cycle, programmed to run when power is abundant like once the solar or whatever is no longer needed to recharge the batteries and such abundant power would otherwise be wasted.
A correctly sized system can be engineered to operate most properly insulated cabinets similarly to the one above, thus requiring virtually no battery consumption.

Cheers OzePete Ozefridge | 12 Volt Refrigeration Systems

[john61ct]

Thanks Pete. Can that setpoint be tweaked by the user?

Or startup triggered by a switch or external relay, e.g BMV-712 based off SoC?

Adapted to freezer usage by stacking multiple units + thicker insulation?

Used for 24V or 48V circuits?

[john61ct]

Same Qs for Rich of course

@SV THIRD DAY

[noelex 77]

This is certainly possible, but you end up wasting a lot of solar power.

The solar panel size needs to be larger, as there is no battery system to help average the times of good and bad solar output. So if you want consistent temperatures, it is easy to cope with the short night time period, but cold storage is limited so the solar output has to large enough to supply enough power for the lower solar output days or even weeks.

Solar is cheap so if you have the room to fit a larger solar array, such as on a roof, and dispense with the complication of a battery system it has appeal, but I don’t think it has any application on a yacht where the room for solar is limited and a battery system is already fitted.

[Uncle Bob]

Originally Posted by noelex 77

This is certainly possible, but you end up wasting a lot of solar power.

The solar panel size needs to be larger, as there is no battery system to help average the times of good and bad solar output. So if you want consistent temperatures, it is easy to cope with the short night time period, but cold storage is limited so the solar output has to large enough to supply enough power for the lower solar output days or even weeks.

Solar is cheap so if you have the room to fit a larger solar array, such as on a roof, and dispense with the complication of a battery system it has appeal, but I don’t think it has any application on a yacht where the room for solar is limited and a battery system is already fitted.

Ah, I read the post as no battery use, not no battery system. As I read it the suggestion is to use excess solar when it is readily available, as in would go to waste, to recharge the fridge with a system similar to that suggested by pete.
But I could be wrong, it has been known to happen.

[OzePete]

Originally Posted by john61ct

Thanks Pete. Can that setpoint be tweaked by the user?

Or startup triggered by a switch or external relay, e.g BMV-712 based off SoC?

Adapted to freezer usage by stacking multiple units + thicker insulation?

Used for 24V or 48V circuits?

Hi John, the Ozefridge's ECO2 set point value (trip voltage that forces the refrigeration cycle to run), is user adjustable although we set it at about 13.5 VDC which suits most situations. Also the controller panel has a switch where ECO2 (the 'start and run when abundant power is available), can be switched off.

Not sure what 'BMV-712 is but the ECO2 power management system is automatic and now standard on all of our hold-over eutectic systems.

The same feature applies to freezer applications.

Cheers, OzePete

[john61ct]

Sorry, Victron's bank monitor, has a programmable relay,

so able to turn a load dump ON

based on its AH counter reaching say 90% SoC, rather than just using voltage.

Or an IGN switch if I want the freezer running as soon as my high-output alternator kicks in. . .