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Old 02-12-2020, 03:32 PM
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Solar Panel Help.

I picked up 8 "grid" solar panels but find they are 36 volt..what can you do with them?

I want 12 vlt or even 48 vlt...maybe 24 volt is possible..any ideas how to get some use out of them?
Alex
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Old 02-12-2020, 04:22 PM
JA
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Originally Posted by xelasnave View Post
I picked up 8 "grid" solar panels but find they are 36 volt..what can you do with them?

I want 12 vlt or even 48 vlt...maybe 24 volt is possible..any ideas how to get some use out of them?
Alex
Hi Alex,

When you say that you "find they are 36 volt", how did you come to that conclusion: measurement of the output or from the info on the name/data plate on the panel. The reason I ask is that a 24Volt solar panel will typically have an open circuit voltage in to the 30Volt plus range.

To be more clear about the possibilities, could you post a picture of the manufacturer's data label?

Best
JA

Last edited by JA; 02-12-2020 at 04:44 PM.
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Old 02-12-2020, 04:50 PM
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Thank you for your reply.
36 volt is on the plate..I have yet to put a multi meter on them to see what is coming out..I can't provide a photo at the moment as they are at the other side of the property so hopefully tomorrow.
Alex
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Old 02-12-2020, 05:03 PM
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I was just now looking at a new panel for sale at Rainbow Power company and it says 36 volts...it may be that 36 volt is what you would use to charge a 24 volt battery.
Alex
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Old 02-12-2020, 05:29 PM
JA
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Yes entirely possible, it all depends on the battery management part of the system/inverter on more modern systems or on the solar voltage regulator in the old school battery only/off grid full-DC systems.

Best
JA
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Old 02-12-2020, 07:12 PM
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I bet 36 is what they use for 24 or double for 48..I need to order another system and was hoping to use these panels, given they were free,..I planned on two 300 watt plus panels..the one I liked was 36 volt.. I did want 2 ...anyways whatever it is 12, 24 or 48 I am only interested in the 240 volt at the power point..I hope that 500 amp hour of battery will do at 12 vlt but probably will go for double so there's $1500 gone, a inverter / charger ($1000) ... and to think 12 months ago I did it all on 120 amp hour battery and 120 watt panel..these folk who think off grid and solar energy will save the world should try providing their own power...and I still need to run a genny for airconditioning.

Happily the new roll off roof observatory is 4 degrees cooler than the van which needs a car port or similar to reduce its oven status....but it's been hot in the van 110 f the other day...that is deadly..for me...I will ring Rainbow Power in the morning and work out the panel problem...I think the ones I have are 150 watts each.so that is 1200 watts..one point two kilo watts system..that sounds good but I still will need to be careful with power..even with 1000 amps of battery that gives you 250 approx to use..and the desk top will chew thru it... easy to do that one a good stack and process..I think but have yet to record data...but that's a decent guess I reckon.

And the fire pump that the tree took out can't be repaired so another grand for a fire pump...might have to start eating the wildlife...lucky I did not buy the 16 inch and suitable mount.
Alex
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Old 03-12-2020, 08:22 AM
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Joshua Bunn (Joshua)
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Hi Alex.
If you are going to use a Battery charger, which I assume you will, that will take care of the voltage for you. Higher voltages at the panels will work better for your system charging, up to a point. For example, I use five 38 Volt panels in series to give about 160 Volts DC in full sun, and four banks of these run in parallel together to give 20 panels in total. This goes to the MPPT battery charger which reduces this down to 55 Volts to charge my "48Volt" batteries but, optimises the power going into the batteries by increasing the charge current. That's the benefit of MPPT charging over PWM charging.


Regards Joshua
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Old 03-12-2020, 12:42 PM
Wilsil (Wilco)
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What you need is a solar regulator what can handle the input of 36V and regulates it down to 12.8V for charging your batteries.
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Old 03-12-2020, 02:30 PM
glend (Glen)
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Alex they should have a sticker on the back that tells you what they are. You cannot mix different voltages but you can use them if you get the right MPPT, basically a charge controller that will drop your input to 12V. I have 24V panels on my shed system, running through a charge controller into my bank of 12V batteries. Just find the right controller and you should be right, but Don't mix different output panels.
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Old 03-12-2020, 03:04 PM
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Thank you all for your help and input.
Here are some photos. I rang Rainbow Power but could not speak to anyone b fore I had to go...later..
I am trying to work out what battery bank I should go for..anyways here are photos.
Alex
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Old 03-12-2020, 03:16 PM
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A 48 volt battery will likely be more efficient than 24 or 12. Depending on how much energy you will use, it will reduce the battery bank size and the cable size needed to charge the battery. You will just need a converter from 48 to whatever voltage you use .
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Old 03-12-2020, 04:25 PM
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Is it all about the money really...at the moment I am thinking 4 acid batteries, Trojans, as I have used them for 20 years off and on... $1500 gets me 500 amps at 12 volt or 250 amps at 24 vlt...the inverter charger then will be around $1000 ...however I have yet to work out my needs given my current set up is not delivering.. the free panels has me thinking of course...heavy gauge wire not a problem as I have 30 mts of welding cable ..been carrying it from house to house for 30 years so I would love to get some value from it.. today I bought the desk top computer to the main house so I could spend time with my daughter and stack some stuff and meant to put a mettter on it to see what it draws.
But forgot..but my guess is probably around 500 watts...say 4 amps..make it 6...so a days work a minimum of 50 amps (12 vlt) so 200 amp hour should service it..but best to go for double so you could think 500 amp hours (25% discharge) will be enough...I just have to watch the cash flowing out..fire pump, ride on mower for fire management, a first person view drone..heck the way its going I will have to eat into the cash set aside for the sports car which is only a investment ...
Plus I need to get the van under a car port structure...or in a big shed..and a bigger better van maybe...

But basically I have everything I want..plus another astro camera..but thats it...for this month.

I plan talking to my neighbour..it turns out he did the solar for the shed here, so I will show him the panels and seek his thoughts. I dont onow why I only now thought of that.
Thanks again.
Alex
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Old 06-12-2020, 06:50 PM
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Alex, a Victron MPPT regulator will do the trick, depending on how much you want to spend and your expansion plans. The regulator I use at our shack is a Victron MPPT 250/100 , not exactly cheap but has bluetooth so you can monitor with a tablet or smartphone. Input can be up to 250V DC and output current up to 100 amps, that translates to around 1200watts at 12V , 2.4kw at 24v and 4.8kw at 48v. At my shack I feed 2 x paralleled strings each of 5 panels for a total of 2Kw. maximum voltage in is around 90 volts, the regulator can automatically select the battery voltage of 12/24/36 or 48 or be manually set. You can set all parameters such as maximum current, float and equalisation voltages from the app. It will also regulate correctly for lithium batteries.
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Old 07-12-2020, 05:42 AM
gregmc (Greg)
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Re discharge depth, lead acid (eg. AGM or Gel) are basically flat at 50%. Lithium (ie. LiFePO4) can go down to around 20 & 30%

When you include depth of discharge and the number of rated cycles for a battery, lithium iron phosphate work out cheaper over their lifetime
(DOD - charge cycle as - look them up in each battery spec)

And a warning, don’t buy cheap batteries from a Facebook add. They are likely to be fake.

Some batteries like enerdrive & invicta have built in power meters accessible via a Bluetooth app.

Also note that some batteries will allow parallel and no series connection (and series with no parallel)

There are some good sources of information from companies like victron and bmpro on the internet

Cheers
Greg

Edit: some Links-
Victron AGM verses Lithium
BMPro information

Victron info on wiring

Last edited by gregmc; 07-12-2020 at 06:17 AM.
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Old 07-12-2020, 01:51 PM
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Alex, a Victron MPPT regulator will do the trick, depending on how much you want to spend and your expansion plans. The regulator I use at our shack is a Victron MPPT 250/100 , not exactly cheap but has bluetooth so you can monitor with a tablet or smartphone. Input can be up to 250V DC and output current up to 100 amps, that translates to around 1200watts at 12V , 2.4kw at 24v and 4.8kw at 48v. At my shack I feed 2 x paralleled strings each of 5 panels for a total of 2Kw. maximum voltage in is around 90 volts, the regulator can automatically select the battery voltage of 12/24/36 or 48 or be manually set. You can set all parameters such as maximum current, float and equalisation voltages from the app. It will also regulate correctly for lithium batteries.
Thanks Phil.
Would it not be..1200 watts at 12 vlt, 600 watts at 24 volts..etc? Off top off my head..let me think it thru when I get home.
I have engaged a neighbour who is an electrical engineer and worked developing solar panels who should be able to take the panels off the roof and maybe help setting up the others.
Alex
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Old 07-12-2020, 01:53 PM
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Quote:
Originally Posted by gregmc View Post
Re discharge depth, lead acid (eg. AGM or Gel) are basically flat at 50%. Lithium (ie. LiFePO4) can go down to around 20 & 30%

When you include depth of discharge and the number of rated cycles for a battery, lithium iron phosphate work out cheaper over their lifetime
(DOD - charge cycle as - look them up in each battery spec)

And a warning, donít buy cheap batteries from a Facebook add. They are likely to be fake.

Some batteries like enerdrive & invicta have built in power meters accessible via a Bluetooth app.

Also note that some batteries will allow parallel and no series connection (and series with no parallel)

There are some good sources of information from companies like victron and bmpro on the internet

Cheers
Greg

Edit: some Links-
Victron AGM verses Lithium
BMPro information

Victron info on wiring
Thanks heaps I am looking forward to looking at the links when I get home. Much appreciated.
Alex
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Old 14-12-2020, 12:25 AM
rickermiler (Rick Miller)
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I also decide to install solar panels in my home house. Like in this review https://websolarguide.com/solar-vents-for-roof/

Last edited by rickermiler; 14-12-2020 at 05:19 PM.
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Old 14-12-2020, 09:34 AM
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Quote:
Originally Posted by gregmc View Post
Re discharge depth, lead acid (eg. AGM or Gel) are basically flat at 50%. Lithium (ie. LiFePO4) can go down to around 20 & 30%

When you include depth of discharge and the number of rated cycles for a battery, lithium iron phosphate work out cheaper over their lifetime
(DOD - charge cycle as - look them up in each battery spec)

And a warning, donít buy cheap batteries from a Facebook add. They are likely to be fake.

Some batteries like enerdrive & invicta have built in power meters accessible via a Bluetooth app.

Also note that some batteries will allow parallel and no series connection (and series with no parallel)

There are some good sources of information from companies like victron and bmpro on the internet

Cheers
Greg

Edit: some Links-
Victron AGM verses Lithium
BMPro information

Victron info on wiring
Those links were very helpful...however I have decided to go with the old acid battery...may be false economy in the long run but I may not last a long run...I will be more than happy to out last the batteries.I am already keeping brochures for old peoples homes and funeral suppliers.

The system has been designed, thought about , adjusted, costed ( I even did a spread sheet), and I am about to order stuff today if I can get motivated..got a touch of cabin fever..rain inside a caravan etc.so maybe just play guitar..the system is to be 24 volt, eight Trojan 250 amp (6vlt) hour batteries to provide (real power over 20 hours) of 450 amps at 24 volts ( which would be 900 at 12 volt..I need to think in 12 volt) ...so 20% of that ...this should be ample...I will leave the current 12 volt set up as is and early days will see the new system as a charging unit for the current 12 volt system with a big lead going to the observatory. I am going for a 1000watt Victron Inverter / Charger and a new solar regulator so I don't have to take the one in the 12 volt system...and there will be fancy fuses and mounting boards..and "enclosures"..never had an enclosure before ..and it will be a professional job as it will be done by my neighbour who was an electrical engineer in his working life...I know I am going over board but the new system will be housed in a new garden shed as will be the genny. I think this set up will allow a comfortable life.

The air conditioner needs the genny but when I get the car port built over the van probably won't need it much.

Again thanks to everyone for your input I greatly appreciate getting all your thoughts as all of this really helps me get things done...
Alex
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Old 14-12-2020, 09:38 AM
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I also decide to install solar panels in my home house.
Welcome Rick...Are you on or off the grid?
I have an inverter for the grid that someone can have if they are connecting to the grid..the panels came to me because my brother in law updated his grid system...so hence the unusable inverter in my possession.
Anyone wants it send a PM
Alex
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