300W+ Solar Panel

Alpina,
I’ll be interested to see the responses you get to your questions. I had similar questions so I emailed Victron Energy about my 100/20 controller. The reply was that anything over 100 volts would damage the controller so it was important not to exceed 100 volts. As to maximum amperage, the controller will take more than 20 amps for input but only “pass” through a maximum of 20 amps of charge to the battery. I have a 15 amp fuse between the panel and the controller that would trip before the controller would see 20 amps on the input side.
The 330 watt panel I was interested in is rated at 69.7 volts open circuit and 6.07 amps short circuit current. Panasonic recommends a 15 amp fuse between panel and controller.
Based on that, I believe I am ok with the 100/20 controller and the 330 watt solar panel.
All you electric experts please correct me if I’ve missed something!
 
Alpina":3e81x2of said:
If I install a 335W panel, will a 100V/20A charge controller work? What's confusing to me is the various voltages and amperages that are quoted. The panel states rated voltage of 57V. Open circuit voltage of 68V. So do I divide 335W/57V to get amps 5.6A? But I know that the battery charges at ~13.7V, so is it 335W/13.7=24.5A?
Click to expand...

scross":3e81x2of said:
The 330 watt panel I was interested in is rated at 69.7 volts open circuit and 6.07 amps short circuit current. Panasonic recommends a 15 amp fuse between panel and controller.
Based on that, I believe I am ok with the 100/20 controller and the 330 watt solar panel.
Click to expand...

On an MPPT controller, there are two sides to it. The solar panel side and the battery side.
The formula is as follows: Watts = Voltage * Amps.
As voltage increases amps will decrease. As voltage decreases, amps increase.

The battery side is going to be between 13.2 and 14.6 volts.
The solar panel side must remain below 100 volts and below 20 amps for the MPPT 100/20 controller.
Because as voltage goes up, amps go down, it's really the open circuit (short circuit) voltage that matters.

Check out this screen shot off my Victron MPPT 100/30 with a 200 watt solar panel putting in 166 watts for an illustration.
http://www.tugnuts.com/gallery2.php?g2_itemId=79485

The top portion (solar) is the Pv (panel voltage). It shows 33.95 volts at 4.9 amps as captured from the sun. 33.95 volts * 4.9 amps = 166 watts.

The bottom portion (battery) is the battery side. It shows 14.6volts at 11.0 amps is going into my house bank. 14.6 volts * 11.0 = 161 watts.

Note: The 5 watt difference is most likely due to the power the MPPT controller needs to operate.
I have the Victron 100/30 (100 volts and 30 amps max).

The open circuit voltage (an electrical short) on the 200 watt panels I went with is 39 volts. When I put two in series that'll double to 78 volts. Peak voltage under normal conditions is 33 volts per the spec sheet on the solar panels I purchased. (66 volts for the pair hooked in series).
400 watts / 66 volts = 6 amps.

On the battery side I should see a max of 400 watts / 14.6 volts = 27.4 amps.

Looking at the specifics of your 335watt solar panel:
Battery side: 335 watts / 14.6 volts = 23 amps. This exceeds the 20amps to the battery, so the excess will be discarded by the controller and only 20 amps would be delivered to your house bank.
14.6 volts * 20 amps = 292 watts.

Solar Panel side: 335 watts / 68 volts = 4.93 amps. (open circuit voltage)
Normal operation on the panel side = 335 watts /57 volts = 5.89 amps. (normal peak voltage)
 
Martin,
Thanks for the detailed explanation.
There’s a big gap in 12 volt panels between the 180-210 watt and the 320-340 watt sizes. Even though 290 watts might be optimal for my system, it’s hard to find a quality panel in that size. My panel rarely puts out it’s full watt rating in power. I’m normally getting 80-90% of the panels rated watts due to temperature and other factors. Going with the 330 watt panel may occasionally provide a bit more amps than my controller can deliver to the battery but I can live with that.
Just wish Panasonic wasn’t exiting the solar panel production business. The typically lower efficiency and lower priced panels from China have driven Panasonic out.
 
scross":sj5dzww1 said:
Martin,
Thanks for the detailed explanation.
There’s a big gap in 12 volt panels between the 180-210 watt and the 320-340 watt sizes. Even though 290 watts might be optimal for my system, it’s hard to find a quality panel in that size. My panel rarely puts out it’s full watt rating in power. I’m normally getting 80-90% of the panels rated watts due to temperature and other factors. Going with the 330 watt panel may occasionally provide a bit more amps than my controller can deliver to the battery but I can live with that.
Just wish Panasonic wasn’t exiting the solar panel production business. The typically lower efficiency and lower priced panels from China have driven Panasonic out.
Click to expand...

It's easier to find the smaller panels than the large one's. When I was researching solar, going above around 300 watts diminishes your selection. I don't know what the largest wattage panel is that they make, but finding them above 330 watts is challenging. (First you have to find them... then you need to find them somewhere that has them in stock).

Also, once you get around 160 watts and above, panels will go from 12volt to 24volt.

WIth solar, you obviously have to size the power requirement to meet the needs of the boat. But then you have the shape and size of the panel, the quality of the panel. Does it handle shading? Is it marine grade to help keep out saltwater? What's the efficiency of the panel. (The highest efficiency ratings I found were just under 25% efficient. I've seen some as low as 9%). I could have gotten a 200 watt polycrystalline panel that's 16% efficient, compared to a mono crystalline panel that's 23.7% efficient. What's the difference? 200 watts is 200 watts... The panel efficiency relates directly to how big or small the panel is.

The Sunpower 200 watt panels I went with are the same width as the factory 160 watt poly panel. But the 200 watt panel is a few inches shorter! 40 more watts and slightly smaller of a panel.

They say, rule of thumb is to take the wattage of the panel, divide by 4 and that's how many amp-hours you can expect in an average day. We saw that with the factory 160 watt panel on our Victron MPPT 100/30 which keeps really good daily metrics of solar power.

I went with 400 watts, but I really just wanted 350 watts. I really liked Sunpower's panels due to their efficiency rating, marine rating, warranty, they look awesome also. (mono panels are black where poly are usually a purple haze). The 175watt panels from Sunpower were only offered in a square format and I needed them to be rectangle. So that left me with either a pair of 150 watt panels or a pair of 200 watt. When hooking panels up in series, it's best that they be the same type/size. I figured with the pair, I'd have port and starboard panels. That would give the panels a slight lean to each side of boat (to hopefully capture more sun rays). The roof rack is not flat/level, as it curves. It also covers both aft hatches on our boat. With the new mounting brackets I went with, the panels are elevated above the roof rack about 2 inches. This lets us open the aft hatches more and it'll allow us to open those hatches when it's raining out. On the flip side, I won't be storing any kayak's up on the roof rack as there's no room.

I totally agree with you and definitely would not worry about your max output of 330 watts being 3 amps more than your controller can handle. Solar spends way more time not at peak wattage than at peak. The larger panel most likely will capture more wattage for you on a cloudy day and be an advantage on the not-so-sunny days.
 
I ordered my split cell 340w panel from platt.com. It’s slightly largely in both length and width but critically if half is shaded I still get half power and not zero output.
 
I've found 2 Sunpower 435 watt panels that were 2 years old for $150 each on craigs list.
The C30 roof cross bars on the roof were only held in with a set screw. The panels took off like a kite loosing my panels on the highway. Lucky no one was hurt or died! Just one was destroyed, other 1 was scuffed.
I then found 2 more Sunpower 435 watt panels that were new from a left over project for $150 each on craigs list again.
Now my cross bars are through bolted. Just returned from a 2,200 mile drive and all is secure.

My panels are about 6 amps at 80 volts. I run them in parallel for better shading performance. Using a Victron 150/70 controller, I see over 2.5kw a day output! It's capable of more, but less than 50% of the charging is at bulk; rest is absorption and float. When my batteries are low and accept more amps, I've seen over 55amp at 14+ volts (AGM) to my 4 house batteries. I have 2 electric fridges, electric stove, 1000 watt micro, electric BBQ, 2 tablets, 2 phones, 4 USB fans, and always on AIS (anchor alarm), underwater lights, and more. I have full batteries back by 11-12 daily even using electric cooking. My 1st outing had mostly sunny days, so the system won't be overkill if its cloudy and only getting 50
5 output.
I've very happy and would do it again.
Both panels use the factory 10gauge wire as I'm only doing 12 amps at 80 volts. The 150/70 required substantial cable upgrade for the 3 feet run at 60 amps.
$300 for solar
$25 for Y adapter for connecting two panels
$650 for charge controller
$40 in 6 gauge wire and connectors.
$15 for a 80 amp circuit breaker from controller to batteries.
$65 gas in my truck to get the panels and back home.
$200 for 8 (4x per panel) super sweet stainless 1" tube to solar mounts that required NO drilling, only a single Philips screwdriver to mount!

Total: $1,300 for unlimited power.

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Gavin,
Thanks for the lead on Platt Electric as a source for solar panels!
The Platt location near me didn’t have any panels in stock. To avoid freight charges would have been a month or two wait to piggyback my panel with a larger order.
So, they referred me to a location 45 miles away. That location had a great deal on a high quality LG 335 watt panel in stock with no shipping charges.
https://m.platt.com/platt-electric-supp ... id=1445099
One of those LG panels is now in the garage waiting to be swapped out for my original 180 watt panel.
Thanks again!

PS: If anyone in the Bellingham WA area is interested in a slightly used Grape Solar 180 watt panel at a good price, send me a PM. I’ll be up there with it mid-June.
 
fantastic! Yes I found calling them was way more productive than using the website. they are definitely an old school company with a bit of tech on the side. we had a good discussion about waiting for a truck to come up from their west coast warehouse to help reduce the shipping.

great to hear you found one locally!
 
im not sure what was installed on your boat but I had to install the MC4 connectors to the existing cables on the roof (make sure you get the right polarity!) and then was able to plug in the panel. I drilled some holes in the frame of the panel to reuse the mounts already installed.
i took the opportunity to move the panel forward away from the shadow creating radar tower
I also added a switch between the panel and solar controller so I can turn off the solar panel if needed. one thing to note. you need to power up the victron controller via the battery before you connect the solar panel to the victron.
 
Gavin,
When I installed my solar system 18 months ago I did it the way you are talking about - panel mounted on 3030 t-slot extruded aluminum rails for maximum flexibility in positioning the panel, all MC4 connectors and an off/on 15 amp circuit breaker between the panel and Victron Energy 100/20 controller.
So swapping out the panels involves removing 6 bolts on the old panel and then reinstalling the 6 bolts on the new panel. Other than the new panel weights in at 45 pounds, it should be very easy.
The existing 180 watt panel was perfect for our boat. Kept the four 115 amp/hr house batteries going for up to 6 days with our daily 65 amp/hours of consumption when on the hook. Then, last month, I bought a Iceco JP42 portable freezer that consumes as much as 50 amp/hours a day. The reason for the solar panel upgrade it to keep that energy hog happy! Now we can pack 2 weeks worth of frozen protein in the freezer and use the freezer to make ice for the Yeti cooler where the veggies are kept.
We will be ready for the Broughtons as soon as they open back up!
 
That is why I went big. Two fridge/freezers consume a lot of juice. Both are maybe 75-100+ Ahr a day. That's without everything else in the boat. A couple meals in the 1000watt micro (130 amps DC) and on the electric stove top (70-100 amps), juice goes quick.
Item using power:

Amps pulled Hours item in use per 24hours Amp hours consumed in 24 hours

Items that are never turned off:
Base draw (C02, BMV712, battery meters, Victron battery sense, etc) 0.74A 24hrs 17.76Ahr per day
Toilet flush LEDs 0.06A 24hrs 1.44Ahr per day
AIS w/(wifi) and VHF spitter 0.3A 24Hrs 7.2Ahr/day
trim tabs with remote off on dash and button off 0.05A 24Hrs 1.2Ah/day
NEMA network (Garmin items, AIS, GPS, etc) 0.35 24 8.4
2x Blue LED USB chargers on dash (aftermarket) 0.01 24 0.24
LED mooring light (24hours. I forget to turn off) 0.15 24 3.6
Inside fridge running (75% duty cycle? = 18 hours on) 2.45 18 44.1
Outside fridge running (75% duty cycle? = 18 hour on) 1.9 18 34.2
Victron SmartSolar charge controller hard wired to battery 0.05 24 1.2

Items that are able to be turned off or variable use:
interior salon lights 2Amps 5Hrs 10Amp hour per day
guest bed 0.5Amps 0.5 hours a day 0.25Amps hours per day
bedroom lights 1.2 2 2.4
under bed LED 0.2 2 0.4
table lamp 3 LED bulbs 0.15Amps 1hr/day 0.15Ahr/Day
inverter in standby (KISE 2000 watt IC122055) 1.4Amps 1hr/day (I keep it off less needed) 1.4Amp hours/ day
stove guess (2 posts say 40Ah per 30min meal) 30min BF or Lunch + diner 120 0.75 90
microwave 1000/1500 act watt = ~105 amps DC 90% efficient inverter 138Amps 0.5 hours/day 69 Amp hour/day
Phone (6 watts or .5 amps while charging) 0.5 3 1.5
Phone (6 watts or .5 amps while charging) 0.5 3 1.5
Tablet (9 watts or .7 amps while charging) 0.7 3 2.1
Tablet (9 watts or .7 amps while charging) 0.7 3 2.1
Garmin GPS map86Sci (complete guess @ .1 amp if stays fully charged 0.1 24 2.4

total Amp hours per day max predicted consumption: 303 Amp hours. This wrong as I can go a couple days on batteries without solar.
solar power generated. 870 watts ( A x V = 870 watts) = ~60amp perfect day 40Amps predicted realistically 5 hours of sun 200Amp hours generated per day from solar.
 
serpa4":1svlzkpr said:
Total: $1,300 for unlimited power.
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Click to expand...

Pretty impressive set up. I found a local dealer to sell me a new Sunpower 335W panel for $175. Will get it in 4 weeks or so.


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