Is the 17 V the peak power voltage (Vpp) or the maximum voltage with the panel unloaded. If the 17 V is the Vpp voltage then they are just normal panels. If the 17 V is the peak voltage then they are an old grid connect panel and they are too low in voltage to charge a 12 V battery. An MPPT (maximum power point tracking) style controller is necessary to boost the charging voltage is necessary. An MPPT controller with an output of 6 A or more will be suitable. However, I would be wary of getting a cheap one through eBay as many of those are not true MPPT controllers.
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PeterD Nissan Navara D23 diesel auto, Spaceland pop-top Retired radio and electronics technician. NSW Central Coast.
Is the 17 V the peak power voltage (Vpp) or the maximum voltage with the panel unloaded. If the 17 V is the Vpp voltage then they are just normal panels. If the 17 V is the peak voltage then they are an old grid connect panel and they are too low in voltage to charge a 12 V battery. An MPPT (maximum power point tracking) style controller is necessary to boost the charging voltage is necessary. An MPPT controller with an output of 6 A or more will be suitable. However, I would be wary of getting a cheap one through eBay as many of those are not true MPPT controllers.
Hi Peter
You have made a mistake here in your answer. A MPPT controller/regulator DOES NOT BOOST THE CHARGING VOLTAGE. And as you say most of the cheap ones are fakes anyway. The MPPT units do boost the current if there is excess voltage available, only. There has been previous false claims made about them on here in the past by non experts.
Trew,
I am not sure what you have in the way of a panel. I have never seen a house panel as small as 60W. It is probably just a normal panel, but hell, how would we know without more information. The panels have several lines of information that might help. My suggestion is to just buy a normal one from Ebay that has the specs and is bigger than 60W. Cheap as chips now.
As far as the controller/regulator goes it needs to have specs that are greater than the panel specs. Mostly for current of more than 3.69 A. Forget a MPPT and just get a PWM one but I strongly suggest you get one with 3 modes not just a single voltage setting.
New 60w 12v panels are around $1w delivered on evilbay at the moment, so s/h from farcebook they'd need to be 50cents/w delivered to even take the risk. If they are cheap then you need a photo of the panel face, there should be 4 x half modules across x 9 x half modules down and the panel should measure some where around 630mm x 540mm.
T1 Terry
__________________
You can lead a head to knowledge but you can't make it think. One day I'll know it all, but till then, I'll keep learning.
Any links to any sites or products is not an endorsement by me or do I gain any financial reward for such links
Is the 17 V the peak power voltage (Vpp) or the maximum voltage with the panel unloaded. If the 17 V is the Vpp voltage then they are just normal panels. If the 17 V is the peak voltage then they are an old grid connect panel and they are too low in voltage to charge a 12 V battery. An MPPT (maximum power point tracking) style controller is necessary to boost the charging voltage is necessary. An MPPT controller with an output of 6 A or more will be suitable. However, I would be wary of getting a cheap one through eBay as many of those are not true MPPT controllers.
Hi Peter
You have made a mistake here in your answer. A MPPT controller/regulator DOES NOT BOOST THE CHARGING VOLTAGE. And as you say most of the cheap ones are fakes anyway. The MPPT units do boost the current if there is excess voltage available, only. There has been previous false claims made about them on here in the past by non experts.
I did not make a mistake. MPPT controllers will only increase the current if the Vmp of a panel is at least a bit higher than the charging voltage of the battery. MPPT controllers will charge a battery when the Vmp is lower than battery charge voltage. In that case they have to boost the input voltage to provide sufficient charge voltage and when doing this the charge current is less than the panel output current.
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PeterD Nissan Navara D23 diesel auto, Spaceland pop-top Retired radio and electronics technician. NSW Central Coast.
I have accidently purchased a 160W folding solar panel for $130. It only puts out 17V no load, but I use a PWM cheap regulator mounted at the battery & it charges the AGM battery fine.
PeterD, some of the DC to DC chargers can do that as part of their normal function even when used as a solar controller, some but not all. There are very few RV MPPT controllers that can and will boost solar voltage and they certainly aren't in the small capacity that seems to be required for this application.
RV type MPPT controllers shouldn't be confused with grid tie inverters that often do have a voltage boosting feature. Most RV type MPPT controllers need to see 7v or more above the battery voltage to turn on, this means with a battery at 13.5v the MPPT controller must see 17.5v min before it will start up and if that voltage rapidly drops below roughly 2v more than the battery voltage, or 15.5v in the example mentioned, the MPPT controller will shut down again.
I have no intention of turning this into an MPPT v PWM argument, Just supporting what Jaahn has posted as being correct in the majority of RV type MPPT controllers
T1 Terry
__________________
You can lead a head to knowledge but you can't make it think. One day I'll know it all, but till then, I'll keep learning.
Any links to any sites or products is not an endorsement by me or do I gain any financial reward for such links
Hello Trew,
You can connect any solar panel to a 12v battery (within reason) via a regulator/controller. Questions - do you have the panel(s) or are you only looking at it(them)? How many are you considering using? What is the load on your battery(ies)?
I too have a small panel on top of my van, an ET 55w panel & it has an output voltage of 21v, not 17. One thing you must realise is that fitting the panel on the roof of a van will give you about 70% of the charge (see our discussion in the "Solar" section called "Cat among the pigeon, can of worms, etc"). However if this panel is sitting at the appropriate angle (on the roof or on the ground) & is in full sun, then you'll get close to your 3.5A, if it's horizontal, you'll get around 2.3A.
I see you too are a Nth Qlder & may not like camping under the full force of the tropical sun, hence the reason why I chose a small top-up panel on top & using up to six portables when I need the extra power.
Which type of controller you use is up to you - bearing in mind that eBay has some el-cheapo's that probably not worth wasting your money on. I'm looking at one at the moment & it offers a 5 year warranty & they are handled by reputable Qld companies.
Now you can go back to the experts (above).
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Warren
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