Houseboat Solar

Sandie

I am looking for guidance in setting up my solar on my houseboat. I will not be running an AC unit. I figure we will use about 1000 watts a day on the busiest of days. (I have googled until I am blue in the face) The houseboat will not be lived on, the houseboat is moored at Lake Oroville, Northern CA. I would like to also tie in my Honda 5000 generator. My thoughts are; 3-300 watt panels, connected to a combiner box, leading to a 60 amp solar charger then to 6 12 volt Marine Deep Cycle batteries. Then lead to  a 3000 watt inverter then to a panel which would have two 60 amp breakers. One side for generator, one side for solar. Is this over kill? I would look at packages but I cannot find a package that uses 300 watt panels. I find most are the 100 watt panels. This is not my first houseboat but I did not install the solar on the other one, I  just enjoyed it.

mcgivor

Welcome to the forum 

Building a system tailored to the load demand is better than looking for a kit that may or may not be sufficient. Size the inverter to actual needs rather than getting a large one thats self consumption may exceed the actual loads. Use larger capacity lower voltage batteries to achieve the desired capacity to avoid parallel strings. Avoid batteries that are listed as marine deep cycle, they are a compromise between starting lighting and true deep cycle.

Choosing a  higher than 12V nominal keeps things easier, smaller conductors, overcurrent protection and so on. The design should start with accurate load calculations, this will determine the battery capacity needed which will in turn determine the PV needed to keep everything working correctly.

Don't impulse buy equipment,

 

Photowhit

So are you saying your daily loads would be roughly 1000 watt hours? Say a TV uses 50 watts an hour if run for 4 hours that would be 200 watt hours. 

As @mcgivor eludes to, there is little reason to have a 3000 watt inverter, particularly at 12 volts, if you have no need for it. I've run my home off 1800 watts for many years until recently. I understand the 12 volt constraints of a boat, lots of things like your marine radio and running lights will be running on 12 volts.

Many 'marine' batteries aren't true deep cycle batteries. Having 6 in parallel creates a lot of problems in them sharing the lad and charging equally. You migh be better off with 2 or 4 - 6 volt golf cart batteries, reducing the strings to 1 or 2.

Sandie

Thank you, I will do more research, I was trying to add to my two current batteries. I do not want to oversize the inverter. I have tried the calculators but find one uses amps, one uses watts, each have different info. The calculator for watts determined 903 watts so I was estimating usage from that. At 72 years young I am baffled at how much or how little I can find on the internet. I do know the basics but putting it together is something else. Maybe overthinking. 

Photowhit

I certainly understand.

Consider that 1800 watts is roughly a 15amp circuit in a home. So it should handle microwaves comfortably. Even a circular saw, though you may want to turn off all other appliances to use one in high demand.

BB.

Amps vs Watts.... When you work with Amps, you also need to state the working voltage to get the "complete picture". With Watts, that "includes" Amps and Volts--So you only need to talk about Watts for power usage.

You can use either, but with multiple voltage systems (you have significant 12 volt and 120 volt loads)--Convertering to Watts and adding the Watts together makes it easier to keep things straight.

Power = Voltage * Amps (current)
Power = 12 VDC * 10 amps = 120 Watts
Power = 120 VAC * 10 amps = 1,200 Watts

Amps = Power/Voltage
Amps = 1,500 Watts (say your AC inverter output) / 12 volts (your DC battery bus) = 125 Amps (nominal--more math needed)
Amps = 1,500 Watts / 120 VAC circuit = 12.5 amps

So your 12 VDC circuit is (roughly) 10x the same power on a 120 VAC circuit.

And when designing your system, as the guys asked above--Watts is a rate of energy usage (like miles per hour)... Watt*Hours is an amount of energy usage (like miles driven).

1,000 Watts --- Is that your peak loads (like running a small microwave and LED lighting at the same time)?
1,000 Watt*Hours -- That would be, for example, 1,000 WH / 5 hours night = 200 Watt average load (for 5 hour period)

To measure your loads (Amps, Watts, Amp*Hours, Watt*Hours), there are lots of nice meters out there.

The 120 AC meter that everyone has used is the "Kill-a-Watt Meter"--But there are many brands these days:

https://www.amazon.com/s?k=kill-a-Watt+meter&ref=nb_sb_noss_2

For DC circuits, there are quite a few options too:

https://www.amazon.com/s?k=dc+wh+ah+meter&ref=nb_sb_noss

Eventually, you probably will want an  AC+DC Current Clamp DMM (digital multimeter)--They are great for debugging, and very easy to measure current--Just clip around a wire (no cutting of wires). There are AC only current clamp DMMs... But we need the AC+DC clamp meter for solar/boats/car electrical systems:

https://www.amazon.com/UNI-T-UT210E-Capacitance-Multimeter-Resolution/dp/B075ZHDQFP (inexpensive, "good enough" for our needs)
https://www.amazon.com/gp/product/B019CY4FB4 (medium priced meter)

-Bill

Sandie

This should be so easy with the 2 existing batteries, solar charger, 1000 watt inverter and generator, BUT it does not work and it is not matching so I want to upgrade and make it work for us. We bought this boat in June and it is now out in dry dock.

I just want to run a couple 12 volt lights at night for a bit (maybe an hour) water pump as needed, phone tablet chargers, 12 volt stereo, and a microwave or toaster now and then, a tv and DVD when the littles are exhausted to calm them a bit. Yes, we have a nice generator but who wants to hear a generator when you are out on the lake. Of course cost is a factor when renovating. This boat will be used by two little 'old ladies mostly, until the family arrives😂

I like the idea of the golf cart batteries so I will do that, buy new solar panels, make sure what this existing solar charger is and figure out what size new inverter we need, hook it up to new panel and breakers and see what I have.

I have never joined a forum before, thought I would give it a try.

706jim

Everything is fine.......until you mentioned microwave and toaster. The other stuff is not a big deal, but those other two are. Running a microwave or toaster is not much different from cranking your engine for a minute continuously as far as amperage is concerned.

BB.

We all work hard here to keep the forum useful and friendly for everyone. No "use the search function" answers.

Highly suggest that you do your design(s) on paper first... Much cheaper than finding out that some of the parts you purchased on sale don't work well together.

Especially, for smaller power systems, conservation / minimizing your loads is the first goal.

Light, there are a lot of 12 VDC LED lights out there these days. For small operations (cabins, boats, etc.) staying with 12 volts can be the easy way out. Short wire runs, and low power requirements.

For larger systems and homes/remote needs, going with 120 VAC (or even 240 VAC) with an AC inverter makes wiring much easier... You can sen more power, farther, with relatively small/cheap copper wiring and standard home wiring supplies. 12 VDC more than a few 10's of feet, becomes problematic (voltage drop because the current at 12 VDC is 10x the same power at 120 VAC--From above). And with 12 VDC, you want around 0.5 volts drop maximum... With 120 VAC, 4-6 volts drop can work OK (not great, but works).

Here is a quick Amazon link showing the wide variety of 12 VDC lighting out there.

https://www.amazon.com/s?k=12+vdc+lights+led&ref=nb_sb_noss_2

I highly suggest that you get one of an LED light/fixture and see if it works for you (color temperature, CRI, beam pattern, etc.) first... There are lots of choices out there and you don't want to buy a 10 pack only to figure out that that 6,000K "white light" makes colors (and people) look pale.

Just to give you something to aim at... "Golf Cart" batteries are typically 6 volts @ 200 AH. You need 2x in series for 12 volts, and you can add the together in strings to add AH capacity (200 AH, 400 AH, 600 AH, etc.). I suggest that you stick somewhere around 1-3 parallel strings.

Inverter wise, a 200 AH @ 12 volt battery will reliably support a suggested 250 Watt maximum AC inverter/AC continuous load. 2x strings or 400 AH @ 12 volts would support around 500 Watts maximum inverter/loads (numbers are really "soft"... 250 vs 300 Watts is not much of a difference).

The downsides of AC inverters--They are around 85% efficient (average usage)... So they waste a bit of power there. Also, just having the AC inverter "on" with no loads, you can waste another 6 Watts to 10-20 Watts or more (larger inverters have higher "tare" losses).

One way to go is to measure/estimate your loads (average Watts, hours of use per day)--That sizes the battery bank.

The other way is to say you only have room for (or want) 4x GC batteries for a 12 volt @ 400 AH battery bank--And plan your usage from that... For example, 5 hours a night, to 50% discharge (for longer battery life):

• 400 AH * 12 volts * 0.85 inverter eff / 5 hours per night * 0.50 max discharge =  408 Watt average load (over those 5 hours)

That is for one "overnight" usage... For a Cabin/home would be suggesting storage for 2 days--But for RVs and Boats, that may not be work the extra battery weight (or reducing the average loads by 1/2).

For a small system (LED lights, radio, cell phone charging, a bit of laptop computer, and RV water pump usage), a 1,000 Watt*Hour per day system is not bad...

-Bill

Sandie

Bill, I agree with the LED lights and will use them. The ceiling is open and i have traced all of the wires now and it seems the existing wiring is good. I think the old system worked for previous owners, I would like to add to it and modernize it for current times. We will have 4 generations enjoying this adventure. I am glad to see comments that do not make me feel like an idiot. 

BB.

When you have the basics worked out for your wiring plan, don't forget the circuit breakers (or fuses).

12 volt batteries can output 100's of amperes into a dead short.

You want a breaker for every positive wire that leaves the battery bus. Sized for the load and awg of the load.

Fire safety is critical for boat and house battery power systems. Don't take any shortcuts.

Bill

Sandie

Bill, I followed the link on Amazon and ordered new LED lights. I plan to add a new panel with two 30 or 60 amp breakers, one for solar, one for generator. I watched a YouTube video of a small cabin system and it looked like that would work, that way you would switch over if you want to use a generator. Kind of like a transfer switch on a home. Yes, safety is very important, we do not want fire. I will also say that I am trying to figure this out and then get someone to look it over.

Sandie

Something like my drawing. 

BB.

Sandie, slow down a bit here... A 300 Watt inverter at 120 VAC is (300w/120v= ) 2.5 Amps AC.

A 5,000 Watt Honda genset is rated for "120/240V 5000W max. (41.2/20.8A) / 4500W rated (37.5/18.6A)"... Or between 41 amps if 120 VAC only  or 21 amps if 120/240 VAC split phase.

https://powerequipment.honda.com/generators/models/em5000

So you have a big "difference" between the output of a 300 Watt AC inverter and a 5 kWatt genset...

What are your 120 VAC loads? Is it just a few small electronics (cell phone and laptop, some USB chargers, an LED TV+DVD or Sat Receiver)--Or are you looking to power an electric range/cooktop, Microwave oven, etc. (from batteries? from genset?).

Having a "mixed" 120 VAC and 12 VDC system, with multiple power sources (batteries, AC inverter, Genset) is actually much more complex than your house wiring.

Just to give you an idea of the complexity of a relatively small 1,200 Watt Inverter-Charger with internal AC transfer switch (Cotek is a very reasonable mid-priced AC inverter system):

https://www.solar-electric.com/lib/wind-sun/COTEK_SC_User_Manual.pdf

I highly suggest you step back a moment and really define your loads first... And understand to generate power with batteries and AC inverters, the higher power/current you want, the more it will cost (and the larger the battery bank and equipment will be)...

For larger inverter/charger systems, there are even prewired panels that are designed to support various models and configurations of equipment to make installations simpler and cleaner:

Just to give you an idea of what a 2,000 Watt 12 VDC/120 VAC inverter-charger with solar charge controller system would entail:

https://www.solar-electric.com/naws-ms2012-pt100-ags-power-panel.html

I am not trying to scare you off... But need to do this in steps. First define your loads (DC and AC), and what you want from the system. A 300 Watt inverter for small loads/quiet time/night time loads with a larger genset for more power during the day (A/C system, microwave, cooktop, etc.) can certainly be done--Just need to define those loads/needs before designing the system. Other questions such as do you want to charge the battery bank from the generator/shore power, or just solar? What about charging from the boat motor?

Again, not right or wrong answers--Just better understanding your needs.

A 5 kWatt genset burns a 1/2 gallon of gasoline an hour (and around 3/4 gallons per hour at full load).

If you need that much power--Energy usage is a personal choice--Not right or wrong.

You can do mixed DC and AC inverter/generator systems for smaller power requirements (like a 300 Watt inverter with a 1,000-2,000 Watt inverter-generator type which tend to be quieter and more fuel efficient for smaller loads--Around 1/10 to 1/4 gallon of gasoline per hour)...

Here is a simplified DC solar + AC inverter (you could substitute an inverter-charger (like the Cotek) for use with a genset:

http://midnitesolar.com/pdfs/Nigeria system.pdf

Another small system drawing:

http://midnitesolar.com/pdfs/MNDC125_Navajo.pdf

A member who does not visit here much anymore has a personal website with his off grid / backup solar system evolution. If nothing else, the pictures and descriptions give you a good idea of what a DIY system entails):

http://2manytoyz.com/

If this is do it yourself project, or you end up hiring somebody to do the actual design and installation--Knowing more about solar/battery/inverter/genset power will be very helpful for you--Both so you understand your loads and the equipment, and when/if working with others on the system.

-Bill

Sandie

Hi Bill, the inverter is 3000 watts. I figure on a busy day at the lake with a full boat, we could use between 900-1000 watts. That is using microwave and or toaster, tv/DVD, water pump, 12 volt stereo, phone chargers, etc. When I used an rv site it suggested calculating amps per week. I did this and my amp use per day would be 59.75.  Then times that by days of use. That is without a refrigerator which I would like to prepare for in advance. Ours is propane now. I will check out the sites you have posted, for now off to the boat for a workday. Thanks for all of your good info.

BB.

Sandie, a 3,000 Watt AC inverter really needs a 24 volt (minimum) battery bank voltage. 3,000 Watts @ 12 volt is:

• 3,000 Watts * 1/0.85 AC inverter eff * 1/10.5 volts battery cutoff voltage = 336 Amps

To reliably run that, you would need an absolute minimum of 1,200 AH @ 12 volt battery bank (that would be, in golf cart batteries, 2 in series (for 12 volts) and 6x in parallel (for 6x 200 AH) for 1,200 AH. Or 12 golf cart batteries...

For various reasons, a 3,000 Watt @ 12 volt AC inverter (with 6 parallel strings of batteries) is just not a good design...

You could do this with a 24 (or 48) volt battery bank (with golf cart, or larger format batteries). But this will not be cheap (and you would need to replace "golf cart" batteries typically every 3-5 years). And most people end up "murdering" their first battery bank or two if they are not very careful.

If you where living on the boat full time and "off the grid"--Perhaps such a system would make sense (going electric instead of propane).

But for a "weekend/summer" usage system (?), generally battery+solar is a pretty expensive solution.

In general, a smaller battery/solar system for "quite times" (LED Lighting, USB loads for cell phone/small audio system/radio/tv) and use a genset for cooking/etc. There is always the question of propane vs electric refrigerators--But electric refrigerators are what take a battery system from "small" to "medium" size--Both in foot print can costs.

I undertand not wanting to hear the roar of a genset while relaxing on the lake... However, I would suggest looking at alternative gensets.

The Honda euXXXX family is much quieter:

em5000s = 66 dB(A) @ rated load; 63 db(A) @ 50% load
eu3000is = 57 dB(A) @ rated load, 50 dB(A) @ 1/4 load (electric start/larger fuel tank version--eu3000i smaller/lighter/pull start)
eu2200is = 57 dB(A) @ rated load 48 dB(A) @ 1/4 load

https://powerequipment.honda.com/generators/models/em5000#Specs
https://powerequipment.honda.com/generators/models/eu3000is#Specs
https://powerequipment.honda.com/generators/models/EU2200i#Specs

10 DB less is 1/10th as loud. You can hold normal conversations standing next to the inverter-generators... They are not bad.

Honda gensets are not cheap--There are lots of new brands of inverter-generators that are much less expensive (quality--I cannot really say)--But for 1/2 the price or less, may be worth a try. Many have remote start/bluetooth/other features...

https://www.generatormag.com/best-inverter-generator-reviews/

Not recommending the website (or generators referenced)--But gives you an idea of what is available for the smaller generators.

https://www.thetoolreport.com/3000w-inverter-generator-reviews/

Another review site for larger inverter-generators.

A Honda eu2200i will easily run a refrigerator/lights/electronics on 1 gallon of fuel for 4-8+ hours. And if you had no larger loads, a small microwave or (smaller, single pad) induction stove.

A 3,000 Watt solar/battery/inverter system will run a small home very nicely. Not a small or "cheap" system. That is a lot of power for a weekend houseboat...

-Bill

Sandie

Thank you Bill for all of your great information. I will check it all out.