New Solar Panel

[bsharp007]

I was given a Sharp 185 Watt solar panel and was thinking about replacing the 90 Watt panel that came with my 2012 Hawk. This thing of course takes up a much bigger foot print on the roof. But my main question is can my current system handle this panel, my controller is the standard Morningside SS-6-12V that FWC is still putting into their campers to handle their solar panel systems. I also have 2 marine batteries.
I'm mainly using the current solar system to power a 80L Dometic compressor fridge that came stock.
Most of the time the 90 watt panel keeps up with the fridge, occasionally the batteries start to fall behind.
Just wondering if it's worth it for me to replace the current stock solar panel with the 185 Sharp? Fyi, I'm a complete newbie in regards to 12 volt stuff, got on the Morningside site and it didn't list the max watts the controller could take.
Any thoughts or insights are appreciated.

 

[dsrtrat]

First find out the output voltage the solar panel, then divide that into the wattage of the panel to get amps.
This will tell you what size controller you will need, your 6 amp controller will need to be replaced with a larger size.
Typical output voltage will be around 17-18 volts but some panels may be as high as 36-40 volts.
It's always better to have a larger controller if you are close to the upper amp limit of the smaller one.
No panel is 100% efficient but it is wise to size for 100% as a precaution.
Dsrtrat

 

[camper357]

Your controller is not big enough.

 

[bsharp007]

OK, just to confirm here's some of the numbers posted on the panel:

185 Watts
44.9 V
Max Power 5.11 amp
Max Voltage 600 V
Fuse 10 amp

Divided voltage into the panel watts it came to 3.7. Am I missing something...probably

 

[mynxd]

bsharp007, you have calculated the amps @ 44.9 Volts. When you change the voltage down to 12 Volts (what you want out of the controller), the AMPS will go up to approximately 15 Amps. your current controller is only rated for 6.5Amps. The Morningstar MPPT controller 15A should handle this panel.

 

[dsrtrat]

Northern Arizona Wind and Sun has a lot of information on solar controllers in their FAQ's section of their store.
I suggest you study this information before you decide on a controller for your high voltage panel.
Dsrtrat

 

[bsharp007]

Sounds like I need to spend a little money, I'll check out that site Dsrtrat recommended.
Just another question though and as you can tell I'm a newbie in regards to electrical, is it worth it to upgrade from a 90 watt to a 185 watt? I do seem to start to run my two batteries a little low after a day or two, I guess my main question is this overkill?

 

[Captm]

No it's not overkill and it's worth the upgrade especially since you already have the panel. Give NAW&S a call and they'll have the answers for you, they are super friendly and easy to deal with.
Cheers

 

[ski3pin]

No it's not overkill and it's worth the upgrade especially since you already have the panel. Give NAW&S a call and they'll have the answers for you, they are super friendly and easy to deal with.
Cheers

I had a similar type of discussion with a tech at AM Solar in Oregon on Monday. The answer I got -"You can't have too much solar."

 

[Spitfire]

Would the existing wiring from the panel down to the controller be adequate to handle the increased load?

 

[ntsqd]

Wiring reacts much more to current than it does to voltage. Current heats the wire, voltage does nothing by itself. If I'm reading it right BSharp's old panel is likely to be a 12 VDC nominal panel, so about 5.25-7 amps in the panel to controller wiring. The new panel is 45 VDC, so at it's stated 5.1 amps max the wiring won't know the difference and given that it's slightly lower current than the low of the present panel and at a higher voltage I would expect the overall system efficiency to go up a little.

 

[RC Pilot Jim]

My 60 watt panel is putting out 20.8 volts BEFORE the controller and 14 volts AFTER the Morningstar SS-10L . That means it is generating
2.88 amps, correct ?

question: Is that 2.88 amps per hour ? Or. Per sunlight day ?

Without sunlight the single battery maintains 12.5 - 12.8 volts overnight just running the 'Engle' on and off

Thanks, Jim

 

[photohc]

Hello Jim,
That would be a theoretical 2.88 amps before the controller. Usually, the 60 watt rating is best case and not the norm. Only way to tell for sure is to have either a Watts-Up meter or Trimetric installed. Depending on the type of controller, the amperage can be more/less. If the controller is an MPPT, then usually your amperage will be more, as the MPPT controller will convert the voltage down to charging voltage and the amperage will go up as a result. MPPT controllers are more efficient in this voltage conversion, which is why they cost more.

The amps is for an instant in time. It will vary depending on your sun exposure. For example, if you have a 70 amp-hour rated battery and run it down by 20%, you've used 14Ah. To bring it back to 100% you need to replace the 14Ah used. If the solar panel is able to generate 2 amps/hour (after the controller), then it will (theoretically) take 7 hours of 2 amps to recharge the battery to 100%.

I have found my 100 watt panel cannot keep up with my daily use (80L Waeco fridge). The fridge alone, draws 3.5 amps during the on cycle. I have since installed a second panel and I can now enter the night with a close to 100% charge.

I hope this is a little more than clear then mud! Harv

 

[RC Pilot Jim]

Thanks Harv,
My mind has always been "fuzzy" trying to understand the process as I understand most hard to grasp theories
experientially. (no wonder I had problems with school).

Observing in the field: My portable panel (October to May) keeps up with the Engle, charges the model airplane Lithium-Polymer batteries and radio maintaining the voltage between 13 - 14.1 volts during the day. 13 when Engle cycles and 14.1 when off. Adding the Fantastic fan speed 1 or 2 drops the voltage to 12.8 (during Engle cycle) during the day.

I don't have 'shore power' in my shell. The panel just charges the battery. Other than the Engle, battery runs the Fantastic Fan, 5 LED lights and occassionally charges airplane batteries. Would you advise keeping the Sunsaver - 10L or switching to an MPPT controler?

Watts-up meter: I use one of those with the airplanes to tell me remaining voltage in a pack after use. If I buy another one do I locate it before or after the controller?
Jim

 

[ntsqd]

You want to know what's going on with the battery. Put any meter between the battery and both the loads and the chargers. What the panel produces might be interesting to some, but is of no direct value to knowing how the battery is doing.

 

[photohc]

Jim, it would best to have the watts-up located after the controller to see what the battery is actually getting from the controller. Locating the watts-up before the controller can also help to trouble shoot if needed. You can accomplish that by installing Anderson connectors, which allow easy connect/disconnect. As for changing out the controller for a mppt version, that can be expensive but more efficient use of the output from the panel. You have a distinct advantage in being able to locate your panel angle and direction. Mine is fixed on the roof. Your Engle is also much more efficient than my 2 way Waeco 80L. If I could find a replacement to the Waeco that is efficient as an Engle, I would buy it. The Waeco is a battery eater on a hot day. Harv

 

[RC Pilot Jim]

Thanks Harv and Thomas. I will get the pieces and integrate into my set up.
Jim

 

[bsharp007]

3.5 amps for the 80L Waeco alone, well that explains why my batteries cans draw down on a warm day. It turns out that the 185 watt panel was too big to fit on the roof, between the rails of the rack. I'm thinking about adding another panel on to maybe another 90 watt panel. I'm guessing I'll still need to upgrade the controller which is currently 6 amps? I also keep reading about MPPT controllers being more efficient, I thought the MPPT were mostly for solar panels that aren't set up as 12volt panels? Would putting a MPPT controller in make any difference with my current Panel?

 

[ntsqd]

From what I've read of the MPPT's it will make a difference, but I'm doubting that it will be enough of a difference.

Adding more panel, with or without the MPPT controller, is likely what is needed. Your current 90W panel will only put out that 90 under ideal conditions, but it is best to size components according to this. Depending on where you want to measure the output, the panel is capable of 4.5A (@20VDC) to 7.5A (@12VDC). I'd say that your existing controller is almost too small. So no way adding a second panel of the same output will work with it. A 15A rated controller would be my starting point for adding a second panel.