1kw+ of solar - how to do it cost efficiently?

[BayouGrande]

We've got a 50' trawler with a flat roof and, after a month in the Bahamas and DR, we've realized we need solar. The generator can't charge our 2700ah 12v house bank quickly enough (100a charger) to make sense and our inefficient refrigeration draws the bank down quickly.

I'd like to add 1-2kw of solar, ideally 1.5. I've looked at Renogy kits but am curious if it would be more cost effective to piece it together myself. Anyone do a similar system or have any suggestions?

Thanks

[pcmm]

Look around, there are much better deals than renogy. Their kits typically ship with cheap PWM controllers that you should just toss in the bin anyway! If you can fit 300 watt panels, you can easily get them for under $1 a watt. Couple that with a real MPPT controller and you've got something, just be aware that 15 kW of generation takes up a lot of space! A 300watt panel is 40" X 80" (roughly) and you'll need 5 of them to get to 1.5kw, and a controller that can handle 150amps.

[Olly75]

Originally Posted by BayouGrande

We've got a 50' trawler with a flat roof and, after a month in the Bahamas and DR, we've realized we need solar. The generator can't charge our 2700ah 12v house bank quickly enough (100a charger) to make sense and our inefficient refrigeration draws the bank down quickly.

I'd like to add 1-2kw of solar, ideally 1.5. I've looked at Renogy kits but am curious if it would be more cost effective to piece it together myself. Anyone do a similar system or have any suggestions?

Thanks

first rule of solar is to use as little energy as possible. So before speccing or designing the system sort the fridge out, either insulate it change the compressor or both. Then look at the other systems, like lights and change for led's etc.

[BayouGrande]

Thanks. All the lights are Led. It's cheaper to add solar than redo the refrigeration given our boat.

[BayouGrande]

Originally Posted by pcmm

Look around, there are much better deals than renogy. Their kits typically ship with cheap PWM controllers that you should just toss in the bin anyway! If you can fit 300 watt panels, you can easily get them for under $1 a watt. Couple that with a real MPPT controller and you've got something, just be aware that 15 kW of generation takes up a lot of space! A 300watt panel is 40" X 80" (roughly) and you'll need 5 of them to get to 1.5kw, and a controller that can handle 150amps.

Thanks! Good info. Space is no issue.

[skipgundlach]

Wow. Lucky you.

Efficiency is what determines watts per square meter, and the rating generally determines the cost.

At the level of wattage you're talking about you could be into the residential or commercial panels and controllers.

By far the most efficient (over 20%, up to 22+) will be SunPower, which controls distribution firmly. However, they DO work with folks like us, and the head of product development and I are doing a tiny (compared to you) deal.

So, if money is the issue, but real estate (how many square meters can you cover and wire) isn't, there are LOTS of ways to skin the cat. But, before I realized that I'd have to rewire and re-control, and would have shading issues, I was about to buy 2 of the 435w panels direct; they actually had 3 of them, and had I been able to use them, would have spent something in the mid-2Ks to get them to Vero Beach FL for 1305w. That same footprint is now more wattage, but as i don't have the use for them, I didn't follow them.

A little while ago, I determined that the 3 kyocera 120/130 panels I had would take just a tiny bit less space than two of their 345w panels; I had a distributor willing to help me, and he now only stocks the 360s at the same price and footprint. Unfortunately, he got the whim-whams from my having tried to help someone else in another forum, a dealer who couldn't buy as well as the master distributor I'd been talking to went ballistic and called him, and the deal disappeared.

So, drop the horse' mouth, scott.mchugo@sunpowercorp.com a note and tell him I said hi. He's their product manager, and will assist you in determining the best route for you. Likely you will be buying several controllers for the size of array you have in mind, but that's not a bad thing, assuming you can fit the wiring, in that it isolates problems should any develop.

I wish I had the space. It would make my life SO much easier right now (distress and anxiety and descriptions deleted as unhelpful)...

L8R

Skip

[a64pilot]

I have 1 KW on a sail boat. I kept finding good deals on panels on the internet, but shipping just killed the deal, makes sense as your shipping large pieces of glass, and that is not inexpensive.
I found an installer in Pensacola that does Commercial and Residential installs. They had some left over panels that I bought for a very good price and went and picked them up so no shipping. About half of what the best deal I could get on the internet.
I also used a combiner panel box like a land based install will, my belief when you get to the size of array your talking that you are essentially a Residential installation.

I would however increase my charge capacity. I did that with an inverter / Charger, mine is 125 amps and that is a common size, but you could more than double charge capacity with a good inverter / Charger and of course enjoy 120 VAC that is silent too.

I think if I were you I would have two arrays with two controllers as opposed to trying to find one big one. Some even run one controller per panel. Myself I would be happy with two so if there is a problem you still have half power. I'd go for 2 KW if I had the space. You have the bank for it

[Emouchet]

Beware not buying residential type solar panel. The panel construction is not designed for usage under salty condition, nor design for the constant vibration, shear and twist a moving boat will bring to them. Cheap panel, for home will died quickly and the waranty will not work.
Have a look to that blog post:
Serious Solar

Also, in less than 2 years from now, new Perovskite technology will boost performance of solar from 18 to 25% (see page 25):
http://img.optics.org/showdaily/PWSD2017Day1.pdf

[skipgundlach]

Originally Posted by a64pilot

I have 1 KW on a sail boat.
clip...

Where did you put that? Even at the current very high efficiency rates, that would take up a lot of real estate (the highest efficiency panels in 360w are 41x61 inches, or 5x10 feet, nominally for a kw, and lots more area for less efficient panels)...

[a64pilot]

Originally Posted by skipgundlach

Where did you put that? Even at the current very high efficiency rates, that would take up a lot of real estate (the highest efficiency panels in 360w are 41x61 inches, or 5x10 feet, nominally for a kw, and lots more area for less efficient panels)...

I have three 250W panels on the davits over the dinghy and one on the Bimini that is attached to the other three forming a T shape.
Not the prettiest things I admit, but the three are the same size as the dinghy and the other is above the Bimini

[hafa]

Originally Posted by skipgundlach

...41x61 inches, or 5x10 feet,...

Small mathematical correction: 41" = 3.41'; 61" = 5.08'.

[Stumble]

Bayou,

For most boats space is very limited and that pushes boaters to use the most efficient panels available. The cost is a little more, but may reduce the space required by 25% or more. The cheap option of you have the space is to use a larger physical array of low efficiency cells.

So before selecting panels you need to decide how much space you are willing to dedicate to them. Fwiw to generate 1.5kw with 20% efficient panels you will need a minimum of 7.5m^2 of deck space. This is for nominal production, actually will be less.

[skipgundlach]

Originally Posted by hafa

Small mathematical correction: 41" = 3.41'; 61" = 5.08'.

Nominally, correct

[skipgundlach]

(3x41=123; e.g. 10 feet 3 inches; 61 DOES equal a smidgen more than 5 feet)

Unless you have some hard constraints (like a wind generator pole, antenna mounts and the like), exact measurements don't usually stop an installation

[briblack]

we've got 1kw. on a 46' sailboat. It's center cockpit, so we've got two 250 watt Kyocera panels on the fixed bimini over the cockpit, and two more on the arch aft. each pair goes to it's own Morningstar MPPT controller. provides a measure of redundancy for breakdowns, etc. works fine, no complaints. If I could, I'd make the panels articulate in at least one axis, to increase yield further. we often see 30 to 40 amps going towards the house bank, but since it's seven, group 31 batteries, it's only 4 to 6 amps each. not a drastic charge. but we're doing OK, it keeps up, day to day. we're running Firefly batteries, which tolerate partial-state-of-charge better than most.