Just upgrade to a new panel - data is in

[derfy]

Just competed a new panel installation. See attached image.

My boat now uses just a single 400 watt panel, mounted on the starboard side of the bimini. I am currently in the Caribbean, with prevailing east wind, so this side is pretty reliably in the sun.

The panel is 80"x40", and I added two stainless tubular bows to the bimini frame to mount it above the canvas. Tubes had to be bent by professionals who have the tooling, and I had the t-joints welded. Wiring from a previous panel installation was already there and I had already an Outback 60 Amp charge controller.

Here are the results of Solar Panel Day 1.

Bottom line is the panel supplied about 42% of my energy needs, based on this one very typical, perhaps ideal day.

My charge controller gives me some fun facts. Note my background 12v house load is about 12 A (mainly from a freezer/fridge icebox conversion, and a separate electric cooler for converting warm beer into cold beer).

Total amp-hrs into the house 12v load and batteries (recharging) ... 121 Ah
Total energy into the house 12v load and recharging ... 1.5 kwh
House 12v range ... 12.1v to 13.9v (I never saw lower then 12.3, so 12.1 was likely a glitch)
Solar panel max output voltage 45v
Solar panel max output current 24.2 A
Solar panel max power 310 watts


Conditions were near ideal, sunny with some very interspersed high cloud cover.

The good news is that this system eliminates one of the two times per day I must run my generator. That is pretty huge. It has been calculated (by a very knowledgeable cruiser I met) that running your generator in the islands cost about 10 USD per hour (fuel, maintenance, and depreciation), and I usually must run it two or more hours to get a full recharge, twice each day. Now I will run it about 2.5-3 hours once a day.

The panel comes nowhere near supplying enough power to handle the total house load, and simultaneously recharge my batteries that have drained overnight. At the end of the day, the house batteries need a good recharge from the generator. I need to make water and heat water also at this time, which I must do with the generator.

So, the total cost of the solar was about $1800 (material and labor - mostly for the shiney stainless steel frame - panel is only about 400 USD), and payback will be in about 90 sunny days on anchor using my friend's 10 USD per hour estimate of generator costs.

Some interesting notes (to me, anyway)...

- All specs are exaggerated by 2x. This brand new "400 watt" panel, on a good day in the tropics, never produced more than 310 watts (according to the logs). I never saw it above 270 watts, and then only briefly. Usually it was 250 watts or less. I expected that, so I am not surprised. So...take all panel specs and divide by 2 get a realistic peak power. (same is true for battery capacity, btw). They are all overrated big time. These numbers will do nothing but go down over time as this panel ages. Of course, average power is what matters and is subject to solar exposure and time of day. But the higher the peak power, the more energy will be generated.


- Payback is much quicker on a boat. 1500 kwh per day is a lot of energy on boat. On land, it is only about 15-30 cents worth of power. We use about a 1 kwh each hour of the day in our condo. Payback on land for this system (which would cost 2x more, since I already had the charge controller, and you would need either batteries or grid tie hardware), is essentially infinite. This is what people are finding out. The payback is longer than the life of the hardware - even with govt subsidies.


- Solar power out is greatly reduced by even modest cloud cover. I have good, real time visibility of the current being delivered into the 12v load. The least little wisp of a cloud overhead hugely reduces the output. Output power is highly variable and very subject to clouds. (As I am writing this, a squall just come over. Power from the panel dropped from 190 watts to 40 watts instantaneously ... in addition to getting my cabin and bedsheets wet - had my hatches open).


- Total Opex? Okay, I now get 40% of my power from solar while on anchor. But have my operating cost gone down? I still have a big diesel generator (whose oil I am about to change, and whose impeller I changed a week or so ago). I cannot get rid of that. I use it less, so Opex is less from lower daily usage, but I still use it daily and have to maintain it. But now I have panel hardware that will depreciate over time (wear and tear and internal loss of conversion efficiency), and that I will have to remove and store the panel whenever I storm prep the boat. That will be a PITA.

I hope this is helpful to anyone considering an installation or upgrade.

Aint it great to be green? I feel so much less guilty now. :-)

[Hartleyg]

Just a couple comments:


"Specs are exaggerated" - your panel is mounted almost horizontal - normal for many boat installations, but NOT what is considered normal for panel ratings - to get the rated power, you have to have the panel fully facing the sun, and this time of year in the Northern hemisphere, a horizontal panel isn't close. The summer will bring you better numbers. Also, you have a sailboat, so shadowing from seemingly inconsequential stuff like shrouds, topping lift, etc. do make a difference.

Your 2X reality factor is probably a useful number, due to the compromises involved in mounting panels on boats, but it isn't the fault of the panel manufacturers!


"...background 12v house load is about 12 A" You may want to look into upgrading your refrigeration setup - spending 3500 watt-hours a day on your refrigerator is pretty high! Adding insulation, reducing box volume and modern compressor setups might be worth the investment.


That 25 amps coming from the panel mandates a minimum of #10 wire, with nice, shiny junctions - #8 would be better, even #6 depending on the length. Every bit of resistance in the wiring represents electrical energy turned into heat - which is NOT useful! This can be a problem in upgraded solar installations, when a large panel (like yours) replaces a smaller one.



Welcome to the solar panel enthusiasts group!


Fair Winds,


Hartley
S/V Atsa

[noelex 77]

Thanks for the report. Solar is great.

You seem to have plenty of room for at least another panel. With some adjustments reducing power consumption, you may be able to ditch the generator completely. It is not hard to make a boat self sufficient with 800w+ of solar in the Caribbean.

This is where the real transformation occurs. Ignore the cost. Quiet, vibration and heat free power with virtually no maintenance and high reliability is priceless.

The sale of the generator will likely pay for the upgrades to reduce the power consumption, such as an energy recovery watermaker.

Just a thought. I hate generators .

[noelex 77]

Originally Posted by derfy

- All specs are exaggerated by 2x. This brand new "400 watt" panel, on a good day in the tropics, never produced more than 310 watts (according to the logs). I never saw it above 270 watts, and then only briefly.

You need to assess the system over a longer time frame, but if the installation has been well done and the solar panels are high quality, you should occasionally briefly see at least close to the rated output of the panel under very good solar conditions.

Even if the panels are mounted flat, it not unusual to see even slightly higher than the rated panel output briefly under exceptionally good solar conditions. While these high output conditions are short lived and therefore do not have much impact on the average output, they indicate everything is performing correctly.

[sv_pelagia]

Definitely, add a second panel... you've got the room. Makes no sense not to.

(Window in bimini to observe sails not that important. On our setup we also had to forgo our little roof window. No regrets.)

[markcouz]

Great report and info, by far the most important of which is Total Energy Recovery of 1.5kWh.

This gives you an efficiency factor of a shade under 4 (0.4kWp x4eff = 1.6kWh). I wish more people would publish this data rather than momentary measurements, which while interesting wont give a realistic indication of performance over a full day.

If you have the time or inclination I would really like to see energy recovery over an extended period (day/week/month/year) - or if anyone else reading has this range of data please publish!

[Randy P]

Nice to see fixed panel use. I’m not a big fan of flexible and semi-rigid panels, but can see where they’d be useful if your boat design dictated that. I agree with getting another panel, but not so much getting rid of your generator, YET. I’m using 2 170W panels on a small power boat and find they’re quite adequate to keep my beer cold and lights on at night at anchor, away from shore power. Like you, my biggest amp hog is the old timey (1977) Norcold (Nevercold) AC/DC fridge.

[derfy]

Originally Posted by Randy P

Nice to see fixed panel use. I’m not a big fan of flexible and semi-rigid panels, but can see where they’d be useful if your boat design dictated that. I agree with getting another panel, but not so much getting rid of your generator, YET. I’m using 2 170W panels on a small power boat and find they’re quite adequate to keep my beer cold and lights on at night at anchor, away from shore power. Like you, my biggest amp hog is the old timey (1977) Norcold (Nevercold) AC/DC fridge.

Attachment 230486

Yes, I previously had flexible panels that quickly degraded. I just hope I can keep for damaging this one when I drop my main. I will try to skew the boom over to the port side when I do that.

[derfy]

Originally Posted by markcouz

Great report and info, by far the most important of which is Total Energy Recovery of 1.5kWh.

This gives you an efficiency factor of a shade under 4 (0.4kWp x4eff = 1.6kWh). I wish more people would publish this data rather than momentary measurements, which while interesting wont give a realistic indication of performance over a full day.

If you have the time or inclination I would really like to see energy recovery over an extended period (day/week/month/year) - or if anyone else reading has this range of data please publish!

I will track it for a while and update this thread. Today's data looks very similar so far. The weather here is extremely consistent this time of year.

[derfy]

Originally Posted by sv_pelagia

Definitely, add a second panel... you've got the room. Makes no sense not to.

(Window in bimini to observe sails not that important. On our setup we also had to forgo our little roof window. No regrets.)

I am considering a second panel. It would easy and not very expensive.

But, take a look at these pictures. Do you think a second panel would add much? In the Caribbean, wind is mainly from the east, so you can count on sun on the starboard side if you are feathering into the wind (and not anchored is a strong current.

In another area I can just slide it over to port.


The empty side gives me room to tuck the sail into the lazy jacks and sail cover.

[derfy]

Originally Posted by noelex 77

Thanks for the report. Solar is great.

You seem to have plenty of room for at least another panel. With some adjustments reducing power consumption, you may be able to ditch the generator completely. It is not hard to make a boat self sufficient with 800w+ of solar in the Caribbean.

This is where the real transformation occurs. Ignore the cost. Quiet, vibration and heat free power with virtually no maintenance and high reliability is priceless.

The sale of the generator will likely pay for the upgrades to reduce the power consumption, such as an energy recovery watermaker.

Just a thought. I hate generators .

Well, I certainly would not be taking out my beautiful Westerbeke 8 kw generator. How would I make water? (required sustained 1 kilowatt for one hour for 30 gal)? How to recharge batteries when on passage and the autohelm is slaving away, pulling several amps, where the sun will definitely be blocked by the mainsail and be at low or obtuse angles when healed? And... we sail at night on passage, pulling power for nav lights, bilge pumps, nav instruments, SSB, etc. No, it not close to realistic for me. It is just not even close.

[derfy]

Originally Posted by Hartleyg

Just a couple comments:


"Specs are exaggerated" - your panel is mounted almost horizontal - normal for many boat installations, but NOT what is considered normal for panel ratings - to get the rated power, you have to have the panel fully facing the sun, and this time of year in the Northern hemisphere, a horizontal panel isn't close. The summer will bring you better numbers. Also, you have a sailboat, so shadowing from seemingly inconsequential stuff like shrouds, topping lift, etc. do make a difference.

Your 2X reality factor is probably a useful number, due to the compromises involved in mounting panels on boats, but it isn't the fault of the panel manufacturers!


"...background 12v house load is about 12 A" You may want to look into upgrading your refrigeration setup - spending 3500 watt-hours a day on your refrigerator is pretty high! Adding insulation, reducing box volume and modern compressor setups might be worth the investment.


That 25 amps coming from the panel mandates a minimum of #10 wire, with nice, shiny junctions - #8 would be better, even #6 depending on the length. Every bit of resistance in the wiring represents electrical energy turned into heat - which is NOT useful! This can be a problem in upgraded solar installations, when a large panel (like yours) replaces a smaller one.



Welcome to the solar panel enthusiasts group!


Fair Winds,


Hartley
S/V Atsa

Thanks for the welcome and a very good comments.
I agree about the specs. It is just worth knowing that it is very unlikely to have a panel square-on to the sun on a sailboat, and even more unlikely that there will be no clouds in the sky. So 2x derating seems about right

Wiring and connectors are very important, but the 25 amps is a peak that was logged and not observed. The panel is typically running 35 volts, with currents of well under 10 amps. I have a 15 amp fuse on the panel, and 10 AWG wire with only one exterior connector to the panel.

The "fridge" is actually a two loads. 7 amps to my ice box conversion freezer/spillover fridge (Seafrost powered), and 5 amps to my Walmart-supplied igloo iceless cooler - used to convert warm beer into cold beer. What could be more essential? Unfortunately the Seafrost duty cycle is near 100%. I just recharged it and that made a big difference, but I still running it max.

I have relined the iceboxes with 2" thick styrofoam blocks cut to fit, and have very tight gasket seals on the lids. Helped a lot. But, ideally a real "do over" would be a bit better, with two independent compressors. But it is not worth it on this old boat. It would be major demolition to redo it and very tough to add another compressor in the available space. I would bet by time I am done, the load would be close to 12 amps, but that is just a guess.

[noelex 77]

Originally Posted by derfy

Well, I certainly would not be taking out my beautiful Westerbeke 8 kw generator. How would I make water? (required sustained 1 kilowatt for one hour for 30 gal)? How to recharge batteries when on passage and the autohelm is slaving away, pulling several amps, where the sun will definitely be blocked by the mainsail and be at low or obtuse angles when healed? And... we sail at night on passage, pulling power for nav lights, bilge pumps, nav instruments, SSB, etc. No, it not close to realistic for me. It is just not even close.

The requirements you quote are quite achievable with 800w+ of solar in most cruising locations. I have owned yachts with all the equipment you mention running virtually 100% from solar power with significantly less than 800w.

One of the consequences of installing a generator for the majority of power, is that the equipment choices naturally are chosen to work with this source of power. For example, the power efficiency of the watermaker is relatively unimportant if you have a generator. Installing a unit that produces the most water within a relatively short time is the overriding concern. This is just one example, but experience operating this equipment can obscure what can be achieved with solar power.

I suspect from your comments switching from predominantly generator power to predominantly solar power would require some significant equipment modifications. These changes may not be practical for your installation. I suspect once you have experienced the easy and reliable power produced by solar you may be tempted, even if your generator is “beautiful” . However, there is no perfect answer to power generation on a yacht.

Living with solar and a generator you will be in a position to make the best choices for your lifestyle, but the goals you outline are quite achievable on solar alone.

[Seadarer]

Sorry about all the math here, but you made me curious.

When I look at the calculations, a 400W panel should generate 400W/12V=33A at a peak with the sun directly overhead. This means that over the course of a day the angle that the panels pointing at the sun is derated by 50% during daylight hours (this is say 10 hours at the Tropic of Cancer in winter) and derated to 0% at night time. Thus, the deration is 50%X10hrs/24hr = 21% of the peak rate. This drops the effective power supply down to 7A on average over a 24 hour period.

Now, unless you continuously turn the panels to point at the sun, this should be further reduced by the angle of the sun in winter. At the tropics, this is as much as 46 degrees, reducing the effectiveness of the panels by a further 30%. Thus the winter power average should be something like 21%X70%=14.7% of the peak rate. This will yield an average power supply of 4.9A over the course of the day.

Since this should be the average winter power from your 400W panel, you might get by with 400W/4.9A X 12A = 980W of panel capacity on a clear day.

Lastly, so long as it does not cloud over or rain for too long you might get by without a generator but still need to keep your power consumption as low as possible.

Personally, I would keep the generator but get more solar panel capacity to make myself largely self sufficient and quiet.

[mvmojo]

We had ten 100w panels on MOJO (1,000 watts total for the math challenged), all mounted flat on the roof (trawler, not sailboat). With a MPPT controller we routinely generated 300 a/h per day from the sun, even in Long Island sound during the summer months all year long in the Bahamas and the Caribbean. With the exception of the hot water heater and the watermaker, the solar panels made 100% of our daily electrical needs. We had a 4.5 cu ft commercial refrigerator and a 5 cu ft. household chest type freezer, both running ac running from the inverter. We had this setup for 19 years and never saw any reduction in solar output from the panels. Prior to installing the panels we ran the 9kw genset 3-4 hours per day. After installing the panels, we ran it for 10-15 min when we wanted hot water for showers and about 2 hrs occasionally to make 66 gal of water via the ac driven watermaker (2 hp 220v ac motor & 2 membranes). For off the grid living, nothing beats solar. It's quiet, much cheaper than a generator and essentially maintenance free.

I'd strongly suggest adding another panel to the bimini. Swing your boom over to the side and lower it down to the side deck to avoid shading the panels...