Just competed a new panel installation
. See attached image.
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)
panel max output voltage 45v
Solar panel max output current
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. :-)