Solar Panels - Fridge Setup

Submitted: Monday, Aug 04, 2003 at 12:45
ThreadID: 6357 Views:2880 Replies:4 FollowUps:7
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Hi all,

This is my first post so hello to everyone.

I am fairly new to solar panels (well no idea really). Ok what I have is this:

I purchased 2 x MSX30 Solar panels from a rural clearance sale in Queensland ($50 each). My friend also purchased some so I can get more if needed. I want to connect these to a fridge for when I do a couple of trips.

I put a meter on it the other day and it puts out about 23v DC.

My first trip is to Birdsville for the races, so I only need power for about 3 days. The fridge is going to be a Engel MT45F.

Ok for my questions, what do I need to do to get this to work.

What battery(s)
Do I need a module so they dont over cook batteries (if possible)?
Will these even do the job?
Any suggestions at all, can I connect these together etc?

Thank you in advance.

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Reply By: Member - Raymond - Monday, Aug 04, 2003 at 16:38

Monday, Aug 04, 2003 at 16:38
Hi Craig
Welcome to the best forum on the web.
You have got a steel at $50.00 per panel.
Either go for a Deep Cycle or Exide Extreme, with a battery isolating system.
If you have the fridge hooked up to the battery, then you should not need a control module as the fridge will be taking power out as the solar units are putting it in. The 23 volts will drop to about 13-14 volts if you connect the solar panels to the battery.
I have just come back from the Kimberley's and a 32 watt panel extended the life of the battery to 3 days while camping, your 60 watts should handle it well for 3 days.
Regards Raywanderin' in retirement. victor 2010
AnswerID: 26769

Follow Up By: CraigH - Monday, Aug 04, 2003 at 16:48

Monday, Aug 04, 2003 at 16:48
Thanks Ray,

Would something like a Pirhana DBE-150 isolating system be ok (150amps)?

What size battery should I look at, amp hours wise?

I am looking forward to connecting this up now, as I wasnt sure it would do the job.


FollowupID: 18292

Reply By: Member - Michael - Monday, Aug 04, 2003 at 16:53

Monday, Aug 04, 2003 at 16:53
I have a single 75watt solar panel mounted on my room and u definetly need a regulator to control the output from the panel.Jaycar do a regulator which also turns the supply on in morn and off 20 minutes after the sun has gone down.They will bleed back power to the panel from your battery if this does not happen.Solar panels are the way to go i used to take a .5kva genset to run fridge but no longer need to.Gotta get out there. Debbie and Mike
AnswerID: 26773

Follow Up By: CraigH - Monday, Aug 04, 2003 at 17:11

Monday, Aug 04, 2003 at 17:11
Thanks again,

I know this may be a stupid question, but anyway.

If one panel puts out 23v and 30amps if I connect two will this jump to 46v and 60amps. If so will the battery charge volatge still be 14v.

I just want to make sure I dont kill the battery.

I had a look on Jay Cars web site, could se a regulator big enough. Dont suppose you know the part number?

Sorry for the stupid questions.

Thank you.

FollowupID: 18294

Follow Up By: CraigH - Monday, Aug 04, 2003 at 17:24

Monday, Aug 04, 2003 at 17:24
watts not amps sorry. Duhh
FollowupID: 18299

Follow Up By: CraigH - Monday, Aug 04, 2003 at 17:31

Monday, Aug 04, 2003 at 17:31
Ok, found a "Solar Battery Charger Regulator M083 " from Jaycar for $22.95.

I assume this is the go.

FollowupID: 18300

Follow Up By: joc45 - Monday, Aug 04, 2003 at 18:07

Monday, Aug 04, 2003 at 18:07
Definitely go with a regulator. Batteries don't like boiling above about 15v for any length of time. Agreed, there's not too much chance of that with two 30w panels, but your batteries are a hefty investment as well. You've saved a mint on panels, treat yourself to a regulator!
I assume your panels are 30watt. In that case, the M083 regulator you chose will not handle the current for both panels (1.5A max). Jaycar have another; MP3126 for about $60 which will handle 20A, more than enough.
The panels, if they put out 23v open-circuit, are for 12V systems, so you have the right ones there. The 23v will pull down to the battery voltage, but will rise as the battery charges, and the regulator will stop the voltage rising above about 14volts once the battery is charged.
The two panels should be connected in parallel, but via isolating diodes to the regulator (don't connect them in series!!). In the terminal box on the panel, there should have been included a suitable isolating diode. This stops current feeding back into a panel, should one get in the shade and the other be in sunlight. If not, just buy a couple of 3A diodes (cat ZR1014 from Jaycar, about 25c) to do the job. Slightly better are 3A Shottky diodes (1N5822, cat Z0042 from Altronics, about $1.50 ea). These have lower voltage drop which will improve the charge current slightly, but there's not much in it really.
If you want to monitor the battery voltage, Jaycar sell a beaut little digital voltmeter cum dual temp guage (cat XC0116, about $40). The temp guage can be used to monitor your fridge. Just wire the power lead to your aux battery, rather than use the cig lighter plug it comes with.
If you can get more panels off your mate at that price, then do so up to the limits you reckon you can carry in your vehicle!!
good luck,
FollowupID: 18303

Follow Up By: CraigH - Monday, Aug 04, 2003 at 19:42

Monday, Aug 04, 2003 at 19:42

Thank you. On the wiring diagram on the back it does say something about diodes, but I assumed that was if I wanted to wire it via diodes. I will have a look at work tomorrow (setting them up after hours) and get back here.

I will order the MP3126 regulator, temp guage and diodes anyway.

Thanks for the part numbers as well.

I rang my mate up and told him, I think he is a little hestiant now to sell them after I told him they will do the job. But by the sound of it these will do the job anyway.

Can you still buy the MSX30 and where if I want more?
FollowupID: 18314

Follow Up By: joc45 - Tuesday, Aug 05, 2003 at 00:06

Tuesday, Aug 05, 2003 at 00:06
Not familiar with these, but a quick Google search on the web indicated they were made by BP Solar, and were 30w. No listing for Aust tho.
FollowupID: 18354

Reply By: bigboy - Tuesday, Aug 05, 2003 at 19:36

Tuesday, Aug 05, 2003 at 19:36
i have a l/c wagon with a engel ss80 fitted it runs 24/7
it has 2 x 45 w pannells with a regulater to stop over charge
i run a exide extreem with 620 cca and 80 ah and cost $110 from
L.C. 4X4 PARTS 0746696639.
THE BATTERY HAS NEVER gorn flat and was all set up by L.C 4X4 PARTS
give them a ring
AnswerID: 26861

Reply By: Leroy - Wednesday, Aug 06, 2003 at 12:10

Wednesday, Aug 06, 2003 at 12:10

Jaycar also sell a 5A regulator that shuts of in low sunlight. Here's the link.

I bought one but in Melb I haven't really have enough sunlight to do much testing!! hehe


AnswerID: 26927

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