Resurrect old solar install

[motion30]

Solar panels are so cheap now, Sun Electrics in Miami has some panels for as little as $0.38 a watt. Many are around 50 to $0.60 a watt. I think upgrading to larger panels might be a good investment

[skipgundlach]

Originally Posted by motion30

Solar panels are so cheap now, Sun Electrics in Miami has some panels for as little as $0.38 a watt. Many are around 50 to $0.60 a watt. I think upgrading to larger panels might be a good investment

Cheap is usually inverse to size per watt.

If you want the biggest bang, replace the relatively inefficient stuff with SunPower celled panels, whether from them or others using them to build their panels.

We nearly doubled our wattage in almost the same footprint by ditching our Kyoceras (370TW) and going to SunPower (720TW). The wiring and controller in place could handle, at the margin, the series voltage of 135, so we went with parallel, as our wiring could easily handle the ~7A per panel (max 14A @ 67VDC) max. Our controller did the heavy lifting, translating that into, so far, a peak of 50A; it can handle up to 60A, which would be absolutely perfect conditions which will never happen in our real-world life.

But it was costly; those watts were much more than those of cheaper panels delivering a third or less, even, of a reduction from our input, in the same size (e.g. our 370W rarely put out more than 20A at 12V, despite being within a couple of inches in length-width dimensions). For us, it was a life-changing event, and a great cost/benefit ratio, to maximize the output in a relatively small space. If we'd had 3x the space, we could have used lesser quality panels...

If I were starting from scratch, and I didn't already have a serviceable controller and wiring (to wire our system was a very large technical/space challenge, best done in a general refit, rather than trying to live aboard and cruise as it happened), I might have used two separate wiring runs and controllers.

FWIW, I found a ready buyer for our 3 panels and analog ammeter with shunt for $200, and a buddy ship took off their 2 of the same vintage and power, and sold their old controller and panels to another cruiser in the mooring field for the same $200. (see above about space/cost ratios)

Sounds to me like a total redesign and implementation might be in order, with some of the costs recovered via recycling (selling) your old gear. There will always be someone who has more real estate than cash....

[StuM]

Originally Posted by skipgundlach

We nearly doubled our wattage in almost the same footprint by ditching our Kyoceras (370TW) and going to SunPower (720TW).

TW? terraWatts?

[newhaul]

Originally Posted by StuM

TW? terraWatts?

I wish I had room for the battery bank to utilize one tarawatt let alone 750 of them
Dang autocorrect.

[hellosailor]

Ex-
An MPPT controller should give you about a 10-15% power gain.
4*75W=300W
2*90W=180W
300W + 180W = 480W at a nominal 14.4V that's 33 amps, and you'll see effectively five hours at that rate in a full day of sunlight, so your panels can provide around 165AH in a given day. Figuring a ten percent charging and system loss...That's more like 150AH even using an MPPT controller, if I've gotten my math right.

Lithium batteries could cut out most of the charging loss--but that's a whole other expensive and complicated topic.

Sounds like you need lots more panels, or a way to significantly reduce your load. Numbers are a harsh mistress.

[Elie]

Originally Posted by TreblePlink

Don't put them in series. Get a little shade on one, and the whole string's output is dramatically reduced.

You have almost 500 watts solar, but your usage is a bit high for that amount.

I may disagree on this statment:
It all depends on the MPPT controller's voltage limit. let say you have 2 array of solar pannels in serie. the total voltage if everything runs well in full sun, is nominaly 48 volts. If one pannel is affected by some shadow, and its voltage drops to 12 volts, the total voltage is now 36 volts( V total = V1 + V2 + V3 ...) . The controller will still be able to extract and convert a maximum amps since the battery voltage is lower than the avalable voltage.

[Excalibur5]

Thanks everyone for your input. I can't justify the cost to upgrade the existing panels. Looks like before shipping for (6) 100w panels and controller I could easily be looking at more than a boat buck, and that would only gain me 120 watts. It seems to make more sense to just buy additional panels and mount to my dinghy davit.

I am thinking 300 watts. Maybe the Renology panels, either 3 100 watt units or a pair of 150s coupled to a victron 100/20 mppt controller. This would bump me up to 780 watts which I sure hope would be enough.

That being said, any suggestions on mounting the panels to the dinghy davits? I have garhauer 1" davits.

[smac999]

Originally Posted by Elie

I may disagree on this statment:
It all depends on the MPPT controller's voltage limit. let say you have 2 array of solar pannels in serie. the total voltage if everything runs well in full sun, is nominaly 48 volts. If one pannel is affected by some shadow, and its voltage drops to 12 volts, the total voltage is now 36 volts( V total = V1 + V2 + V3 ...) . The controller will still be able to extract and convert a maximum amps since the battery voltage is lower than the avalable voltage.

atcual testing proves otherwise. series systems stop producing when one is covered.

https://www.youtube.com/watch?v=1qD3mN8VotQ

[mitiempo]

Originally Posted by Excalibur5

I currently estimate I use 200 amp hours daily at anchor, and 300 amp hours daily while underway.

It would be interesting to see a breakdown of this excessive consumption. Actually measured ideally vs a guestimate.

[Pete7]

Originally Posted by mitiempo

It would be interesting to see a breakdown of this excessive consumption. Actually measured ideally vs a guestimate.

The two fridges and watermaker are the high current items especially as he heads south.

I would suggest a Smart gauge but that will likely have the thread go completely off at a tangent. However, perhaps some form of battery monitoring is needed first before expensive purchases and decisions are made.

Pete

[travellerw]

Originally Posted by smac999

atcual testing proves otherwise. series systems stop producing when one is covered.

I appreciate you posting this as I had not seen this video yet. There are some issues with their tests (they even say that in the video, lots of variables). I do think the basis of their test was valid. I think the important thing to take from that video is you need to assess your boat and your situation. On a monhull where you may have loads of shade from the boom or even backstays parallel is probably best. On a catamaran, it may be a different story.

I can only give my real world performance on my catamaran. Our panels are split in banks that are all in series. They are way out back over the dinghy davits and have VERY little shade. We get great performance out of them. In fact the history log in the Victron MPPTs shows exactly what I would expect when I compare with other cruisers in the same area. Cloudy days kick the crap out of everyone's performance (series or parallel).

However.. You this has peaked my interest.. It may be an interesting experiement to swap one of my banks over to a parallel configuration and see the difference in the real world. Of course there are lots of variables that would skew the results (time of year, weather, ect), but might be a good "Poops and Giggles" excersize!

Back to the OPs problem.. I think he is on the right track with adding more panels and switching to MPPTs. Another suggestion would be to look at the wiring and ensure its properly sized. You may be throwing some power away there.

[skipgundlach]

Originally Posted by smac999

atcual testing proves otherwise. series systems stop producing when one is covered.

Interesting video. Where did they find panels without blocking diodes in this day and age???

And, as I am on limited bandwidth, I didn't get it all, but on my setup, when I have a charged battery, the solar can be at zero (nominal; I'm not sure it would ever be zero due to loads I normally would have on) amps at high noon (otherwise possibly 50A output). My apologies if it was covered, but what allowances does this video make for battery state?

(I can prove my personal case by looking at the output and then adding a load. When charged, the amps immediately jump up to cover the load; turn off the load and they drop again. I have done that to confirm my "automatic rough - a pilot's term of hearing his engine supposedly misperform when in dicy landing conditions, when in fact it's not - fear that something is "off" with my setup.)

[Wayfarer1008]

Being a person who has installed and maintained remote Seismograph stations The two big factors for loss of power were corrosion of wires, panels and oxidation of the surface of the silicon wafer solar panel caused by UV radiation. Hearing your system is 16 years old is a good testament to your maintenance of the system in that most systems suffer from major corrosion issues after about 10 years with UV starting to seriously affect the performance of the panels after about 15 years. With your system I would start with looking at your energy loss from corrosion in the wiring then move to your sequencer. For our applications we never wanted anything to run hot so we would purposely would install sequencer's that could carry up to double our output.

[Excalibur5]

Originally Posted by Pete7

The two fridges and watermaker are the high current items especially as he heads south.



I would suggest a Smart gauge but that will likely have the thread go completely off at a tangent. However, perhaps some form of battery monitoring is needed first before expensive purchases and decisions are made.



Pete

Pete-

Excellent point. For some reason I can't seem to get the spreadsheet to import here, but my estimated daily totals come to 187 AH anchored, 269 AH at sea.

I do have an ample power emon 2 system aboard. Currently, not using the water maker, my house load varies from 4 to 8 amps, steady while tied to the dock, so the above numbers look about right. At anchor we usually see daily use around 130-150 AH currently in AK, and that number will grow in the tropics due to more load from the fridges and the water maker.

Note this is on a fully outfitted Prout Snowgoose with a family of 5 aboard, so that is why the load is so high.

[travellerw]

Originally Posted by Excalibur5

Note this is on a fully outfitted Prout Snowgoose with a family of 5 aboard, so that is why the load is so high.

What are your kids ages? Do you have any generator capacity?

We are a family of 5 with kids ranging from 7-11. We found that our first year we were flush with power. However as the kids settled into the life, we used more and more power. We have very limited "screen time" for our kids, but we do have some. Those damn tablets, Kindles and Game Boys really add to your daily draw.

For us, we allow them to have unlimited game time on laundry day. On those days we run our Honda 2000 to make water and run our tiny washing machine. We let the kids use some of the excess of the Honda for their gear!

Which brings up something no one mentioned. A Honda generator.. you can purchase a Honda 2000 in the USA for about $700. Its always and option to run the generator 1-2 hours every day or two. Even with the cost of fuel down here its a very cheap option (we spend about $12-15/week on gasoline for our generator, including making water as our watermaker is 110V). Cheap, simple, takes up little space and provides a good backup for power.