Solar package review for Houseboat- feedback and suggestions please

[SteveCA]

Hi guys,

I have done a fair amount of internet research on solar for RV's and Boats over the past few months and am embarking on an install of a system for a houseboat. This forum has been a wealth of information and damn funny to read too (you know who you are....)!

Our daily requirement is about 3000 watt hours mostly from the usual suspects: microwave, coffee maker, cabin lights, water system pump and cell phone charging. I am looking at the following setup:

3 Sharp 235 watt panels (B grade panels, 90 day warranty at .85/watt)
Morningstar TS-RM-2 remote meter
Morningstar TS-60-MPPT controller, controller breakers (with box), mc4 extension for the string of panels, a combiner box (with string breakers), and 10/2 cable for running from the combiner to the controller
4 Costco golf cart batteries
Xantrex PROWatt 2000 Inverter

This will be added to the existing 2 trojan 105's ( 6volt wired in series)

The boat has a generator and shore power which is not used as the dock has no shore power.

Background info:

Boat is located at Lake Shasta, California and is primarily used in the summer months where days are in the 90's and sun is available all day from 9 am (we park facing eastern shore) to 8PM. Winter use is almost non-existent.

I have several questions:

1. is the system sized appropriately to provide the required daily power needs? is the ratio of panels wattage to battery storage sized correctly? Can we get by with two panels instead of 3?
2. is there a way to power the inverter with 24V while supplying the boats systems with 12 volt using the same bank of batteries?
3. Is the extra cost of the MPPT controller cost effective when compared to a PWM controller at 1/3rd the cost
4. is it prudent to add new batteries to the existing batteries (2 years old not babied)
5. is it possible to add an automatic transfer switch that shuts down the inverter when the generator is started? if so, what switch do you recommend? I am not worried about shorepower as it is never used and we will put a big sign on the receptacle just in case.
6. are Sharp B grade panels reliable? the warranty is very short but the dealer claims that they have never had a warranty claim or return on the Sharp panels.

sorry for the 64 questions, Thank you in advance for your feedback.

[Sunking]

Steve sorry to bust your chops but what you propose is not going to give you 3 Kwh/day usage. You do not have enough of anything to come close to that.

For example if you were to use the T-105's, which is a horrible choice for this, will take 12 of them to give you 3 Kwh/day, and a minimum of 1500 watts in solar panels to support the batteries and generate a minimum of 3 Kwh/day usable energy. Sorry guy no point in answering your questions as you are not even close.

[SunEagle]

Steve sorry to bust your chops but what you propose is not going to give you 3 Kwh/day usage. You do not have enough of anything to come close to that.

For example if you were to use the T-105's, which is a horrible choice for this, will take 12 of them to give you 3 Kwh/day, and a minimum of 1500 watts in solar panels to support the batteries and generate a minimum of 3 Kwh/day usable energy. Sorry guy no point in answering your questions as you are not even close.

Maybe if he didn't run his microwave, coffee maker and water pump from the batteries he could get by.

[SteveCA]

Thanks for the chop busting but that's why i'm here. Let me ask the question a different way. What would it take to provide 3Kw on sunny days, in the summer from mid may to early september. We don't care about the other months or cloudy days. That's what the generator is there for. From what I've seen, folks in similar lattitudes are getting 1-1.2 KW per panel per day, on sunny days on their grid tie systems. is off grid systems that much more inefficient? I an here to learn so chop busting is fine with me. Thanks for your help.

[SunEagle]

Thanks for the chop busting but that's why i'm here. Let me ask the question a different way. What would it take to provide 3Kw on sunny days, in the summer from mid may to early september. We don't care about the other months or cloudy days. That's what the generator is there for. From what I've seen, folks in similar lattitudes are getting 1-1.2 KW per panel per day, on sunny days on their grid tie systems. is off grid systems that much more inefficient? I an here to learn so chop busting is fine with me. Thanks for your help.

It's not the solar panels that are holding you back it is the battery system that needs to be real big to handle your needs at night.

Even on sunny days if you had a 3kw system you would only get that much output for a few hours tops. The rest of the daylight would only yield a portion of the total system wattage. To get your 3kw all day long would require a system many times the size of the 3kw. Your house boat will not be big enough to mount them all.

[SteveCA]

It's not the solar panels that are holding you back it is the battery system that needs to be real big to handle your needs at night.

Even on sunny days if you had a 3kw system you would only get that much output for a few hours tops. The rest of the daylight would only yield a portion of the total system wattage. To get your 3kw all day long would require a system many times the size of the 3kw. Your house boat will not be big enough to mount them all.

Okay, I'm trying to understand the math so tell me where I went astray/mis-represented my needs. I believe I may have misrepresented my needs. I don't need a constant 3KW. I need 3000 watt hours total per day:

The 3 X 235 watt panels, assuming 6 hours of full sun per day, theoretically put out 4230 watt hours. Assuming 70% efficiency in the charge controller and inverter (for microwave and coffee pot use), the daily supply should be about 3000 watt hours. 6 golf cart batteries with a total of 600 amp hours at 12 volts discharged to 50% yields 3600 watt hours per day. In reality, the lionshare of the use will be during the daylight hours, not at night so I assume that the batteries will rarely discharge to 50% on sunny days. If we have cloudy days, which is fairly rare, we will curtail use and run the generator for all AC usage. this is the math behind my proposed design. What have I missed?

[SteveCA]

I should also add that the usage on this houseboat is not daily. It is a weekender to one week max usage several times a summer. I understand that the proposed sizing may be on the light side, but keep in mind the light occasional usage, all of which is in the summer, with a 10 KW westerbek generator for any serious loads or microwave heavy days. We are mainly trying to avoid running the generator first thing in the AM for a cup of coffee or a 40 second microwave blast for some bacon. The proposed solar installation is by no means a stand alone system for the houseboat.

[SteveCA]

BTW, Here is a link to a pre-packaged system for 2940 watt hours per day:

http://www.wholesalesolar.com/products.folder/systems-folder/REMOTETELECOM.html

It uses 3 ET 245's so I am 30 watts shy of their packaged system.

[russ]

BTW, Here is a link to a pre-packaged system for 2940 watt hours per day:

http://www.wholesalesolar.com/products.folder/systems-folder/REMOTETELECOM.html

It uses 3 ET 245's so I am 30 watts shy of their packaged system.

A very different application - you are wanting instantaneous draw of high current - hang loose as one of the guys will be along to help you.

[SunEagle]

BTW, Here is a link to a pre-packaged system for 2940 watt hours per day:

http://www.wholesalesolar.com/products.folder/systems-folder/REMOTETELECOM.html

It uses 3 ET 245's so I am 30 watts shy of their packaged system.

Careful. That item delivers 2940 watts per day not watt hours. It will give you about 735 watts for only 4 hours each day. The watt output goes down before those 4 peak hours and after those peak hours even with the sun shining.

It doesn't give you the size of your battery system which is what you really need to know to handle any loads when the sun isn't providing peak power.

It is a nice system but may be much smaller than what you are looking for.

[Sunking]

I should also add that the usage on this houseboat is not daily. It is a weekender to one week max usage several times a summer.

OK this makes it a full time system being in the boat for a full week.

You have two issues but workable.

The big one in my opinion is the batteries. They are undersized and wrong type for the application. If you intend to use 3 Kwh/day, then the batteries need to have 15 Kwh capacity. At 12 volts 15,000 wh / 12 volts = 1250 AH. Using 225 wh 6 volt batteries in parallel is not the way to go and asking for failures and a maintenance nightmare. Instead you want to use 1250 AH cells like a Roll S2-1275AGM 2 volt 1200 AH battery if the batteries will be used for engine cranking, or if no engine cranking then a Rolls S-1590 2 volt 1200 AH Flooded battery.

For the panels is not a huge issue because you do have the generator, but will need a good battery charger. The problem with the panel is on paper you have enough wattage to generate 3 Kwh/day you desire, bu tin practice will fall short because the calculations assume perfect orientation and tilt angles on a fixed system like a house. On a boat you cannot have that and orientation and tilt is dynamic changing every second with your direction, pitch, and roll. On a boat you will likely have to mount them flat on top of a deck, then you might have shade issues casting shadows from mast and sails if it is a sail boat. You will never be able to achieve full production.

[inetdog]

The problem with the panel is on paper you have enough wattage to generate 3 Kwh/day you desire, bu tin practice will fall short because the calculations assume perfect orientation and tilt angles on a fixed system like a house. On a boat you cannot have that and orientation and tilt is dynamic changing every second with your direction, pitch, and roll. On a boat you will likely have to mount them flat on top of a deck, then you might have shade issues casting shadows from mast and sails if it is a sail boat. You will never be able to achieve full production.

For a general case boat, these are all important, and in addition will include concerns about running the main engine or a separate generator, etc.
But the OP has a houseboat.
The tilt and fine orientation while moored are going to be issues, and flexibility to re-aim the system if the boat is moved may be issues, but not on a day-to-day or hour-by-hour basis.

[SteveCA]

OK this makes it a full time system being in the boat for a full week.

You have two issues but workable.

The big one in my opinion is the batteries. They are undersized and wrong type for the application. If you intend to use 3 Kwh/day, then the batteries need to have 15 Kwh capacity. At 12 volts 15,000 wh / 12 volts = 1250 AH. Using 225 wh 6 volt batteries in parallel is not the way to go and asking for failures and a maintenance nightmare. Instead you want to use 1250 AH cells like a Roll S2-1275AGM 2 volt 1200 AH battery if the batteries will be used for engine cranking, or if no engine cranking then a Rolls S-1590 2 volt 1200 AH Flooded battery.

For the panels is not a huge issue because you do have the generator, but will need a good battery charger. The problem with the panel is on paper you have enough wattage to generate 3 Kwh/day you desire, bu tin practice will fall short because the calculations assume perfect orientation and tilt angles on a fixed system like a house. On a boat you cannot have that and orientation and tilt is dynamic changing every second with your direction, pitch, and roll. On a boat you will likely have to mount them flat on top of a deck, then you might have shade issues casting shadows from mast and sails if it is a sail boat. You will never be able to achieve full production.

Sunking,

Thanks for your feedback. I intend to wire the 6 volt batteries in series, in sets of two, and then parallel wire for the three sets to get 12 volts. I prefer to wire 4 6V batteries in series to get to 24V (for the inverter), but the boat systems all run on 12V. I understand your suggestion on the batteries and it looks like your design calls for 20% discharge which I understand is best for longevity. We will have to consider the cost benefit of using a lot more batteries versus shorter life. for us, the boat is used at most 40 days a year so I wouldn't be upset with 200 cycles of life under higher discharge percentages. that should give us 5 years which I understand is the likely useful life of the batteries.

As far as the panels and shade issues, we are quite fortunate because the boats tends to spend the entire day docked in an Idylic cove with no pitch or roll because the front end pontoons are beached and the boat is tied off to shore. The panels will be mounted flat on the top roof where there is no shade whatsoever. As I understand it, the ideal tilt during the summer months is around 12 degrees facing south. We will be at 0 degrees facing south with 12 hours of sunlight. i know they are not all full sunlight hours but in the summer, at least 5 of those hours are close to full sun.

I would like to know what you think of using Sharp 235W B panels. Are they reliable? the warranty is only 90 days.

[SteveCA]

Here is a photo of how the Houseboat is used. Basically is is used like a house. I may move once every 3-4 days at most. As you can see, there is a lot of unobstructed space on the roof for panels. Lake Shasta sunny on 95% of the summer days. the only issue is heat. It can get quite hot with temps in the high 90's and occasionally over 105. BTW, this is not the boat we are installing the system on. Our boat has no rails on the top deck.

Constellation 01.jpg

[rzelred1]

Houseboat solar at Shasta Lake

Hi Steve, Can you tell me what you finally did for a solar system. I also have a houseboat on Shasta Lake. I just put it in dry dock and plant to install solar panels. i keep hearing about issues with 36 volt panels on a 12 volt system causing problems. We have 4 6 volt batteries and want to add 6 110 watt 38volt panels. I'm trying to find someone who can look at our system and tell us if what i want to do will work.
Thanks Ray Zeller

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