A Solar Powered Office on the water

[digitalnomad]

I have been researching for weeks on what might be the right solution for an offgrid office on the water.

I am looking at converting a Bavaria 36 into a remote office. She is currently on the hard in Greece awaiting its usual maintenence prior to returning to the water. This gives us a great opertunity to add the power system.

The key questions which I seem to get very different answer to are:

1. What is the best arch for a Bavaria 36, to give a strong base for rigid solar panels?
2. What are the best solar panels at the moment?
3. What are the best solar controllers at the moment?
4. What are the best batteries at the moment?
5. Why can't you just buy a kit for this kind of system?

From talking we differnt suppliers in several countries they all seem to point towards a 4 rigid panel system, with supplimentory support from flexible panels if the need arises.

How to calculate the usage of a coffee machine, monitor, macbook pro and the firdge are also very difficult concepts and every supplier gave me different opinions none of them related to any mathmatical calculations.

The trend seems to point towards a system running 4 rigid panels in parallel with 5 x 100ah storage and the most expensive controller you can find.

I have been told that I should get 4 x 140w panels as that seems to be the normal panels in stock. One supplier recommended the 160w panels but not one of the suppliers could explain the requirements in detail.

The closest to a real scientific answer was that you should expect between 25% - 75% of the capasity of the cells. That I would need to work during solar hours only as even with a 500ah storage you would only get a couple of hours out of the batteries before they are reduced to the minimum 50%.

I was also told to sail the boat around the coast with a Hydrogenerator as nothing else would really meet my needs (have you seen how much they cost?).

So ... sorry for the long explanation, but I would love to hear from someone that has real experience with running an office on the water so that I can try to get a system or systems working for this year.

[Simon.Sails]

Interested in this as well, sorry don't have any answers from experience. I think there are so many variables involved you'll have to do the math (excel spreadsheet) yourself.

Calculate your total consumption at anchorage (I don't suppose you'll work during a passage?) and then get a conservative estimate of your solar output on a regular day.

Obviously a catamaran with more real estate for solar would be better, but I guess you already have a boat.

There are a number of YT videos with their own power generation/consumption estimates:

https://www.youtube.com/watch?v=5JOI...=O%27KellyTech

[dougweibel]

If you have no experience living on a boat then estimating your power needs will be difficult. So much depends on the boat and your expectations. Some people on some boats could easily get by on 100Ah per day, perhaps significantly less. Other people on other boats might burn through 500 - 1000 Ah per day. We are anchored next to a big cat with 4200 watts of solar. I'm guessing they use a lot more energy than us.

Then on the solar side a lot depends on season and geographic location. Higher latitudes in winter with cloudy skies is massively different than low latitudes in summer with clear skies. Your idea of 25% to 75% of the rated output is incomplete. You will likely get somewhere in that range for some number of hours in the day, but when the sun is low in the sky you get less unless you change the angle of the panel to be more perpendicular to the sunlight. I don't count on good output for a couple hours after sunrise and before sunset.

An office does not need to consume a lot of power, but it could, again depending on your expectations. We run two MacBooks on our boat daily and they are only a small contribution to our energy budget. We don't run processor intensive applications all day and we don't use external monitors. A coffee machine should be pretty easy to estimate. What is the watt rating, how long does it take for a brew cycle, and how many cycles a day? Divide your watt rating by 12, or the house bank voltage you are contemplating, to get approximate amps.

With your apparent experience and knowledge I'd be very wary of anyone suggesting a hydrogenator to you. They are most useful if you spend a lot of time sailing at reasonable speeds and are generally useless at anchor. It seems more likely a wind generator would be a better option, but again that is geographically dependent.

[Adelie]

Originally Posted by digitalnomad

I have been researching for weeks on what might be the right solution for an offgrid office on the water.

I am looking at converting a Bavaria 36 into a remote office. She is currently on the hard in Greece awaiting its usual maintenence prior to returning to the water. This gives us a great opertunity to add the power system.

The key questions which I seem to get very different answer to are:

1. What is the best arch for a Bavaria 36, to give a strong base for rigid solar panels?
   Depends on how many panels and if you intend to use it for other things like acting as a dinghy davit.
2. What are the best solar panels at the moment?
   Define Best. Best efficiency? Cheapest? Best bang for the buck?
3. What are the best solar controllers at the moment?
   Define best? That asked I would go with Victron BlueSolar controllers, 1 small controller per panel. Yes you will pay somewhat more than getting 1 or 2 large controllers but you gain redundancy and most importantly you limit the effects of shading on panels. With multiple panels feeding 1 controller, if one panel is shaded it drags production down on all the panels.
4. What are the best batteries at the moment?
   Define Best. Do you have access problems where the batteries will be installed? That is can you get in and add water every 3-4 months? Do you need super high output to run something on the boat?
   Like electric propulsion (EP) or an electric galley (EG). How are you recharging most of the time? Plug in at a marina or generator/alternator or solar or wind? Best bang for the buck is DIY LiFePo. If you don't want to do DIY then Golfcart Flooded Lead Acid (FLA) is next (Trojan SPRE 06 255), then Firefly G31 and Battleborn LiFePo. The only time you want AGMs (including Firefly) is if you have need of high amp output and have access to high amperage recharging (generator, shore power or high output alternator on main engine). If you have access issues then I would go LFP or Gel.
5. Why can't you just buy a kit for this kind of system?
   Because electrical needs, available space, available charging and sailing locale vary so much boat to boat.

From talking we differnt suppliers in several countries they all seem to point towards a 4 rigid panel system, with supplimentory support from flexible panels if the need arises.
I would Put the biggest panel I could on an arch over the stern that was not used for anything else. I would put panels atop the bimini, 1 or 2 per side, leave a gap in the middle. I would put 1 panel per side on the dodger.

How to calculate the usage of a coffee machine, monitor, macbook pro and the firdge are also very difficult concepts and every supplier gave me different opinions none of them related to any mathmatical calculations.
Rule of thumb for refrigeration is 50Ahr/d per unit.
Will vary some with specific unit, insulation, sailing locale, season. For the rest spend $30 and get a energy meter. Plug each item into the meter for a week at home and see how much each uses. The assumption here is that you will use the same things afloat the same amount as on land. I tested a breadmaker, 330Whr per 2lb loaf, that's about 30Ahr at 12v.

The trend seems to point towards a system running 4 rigid panels in parallel with 5 x 100ah storage and the most expensive controller you can find.
As previously indicated, 1 small, good controller per panel. 500Ahr capacity is probably a good starting place. If you want an electric galley then 750-1000Ahr. If you want to go with EP then that's a special discussion.

I have been told that I should get 4 x 140w panels as that seems to be the normal panels in stock. One supplier recommended the 160w panels but not one of the suppliers could explain the requirements in detail.
I would get the biggest panel that would fit each space.
200W or more for the arch, 160W or more for each side of the bimini, 50-75 for each side of the dodger. If you only get one controller then all the panels should be the same. Side effect of multiple controllers is if a panel dies, you can replace it with something different from all the other panels, you don't need to match it almost exactly.

The closest to a real scientific answer was that you should expect between 25% - 75% of the capasity of the cells. That I would need to work during solar hours only as even with a 500ah storage you would only get a couple of hours out of the batteries before they are reduced to the minimum 50%.
Rule of thumb for MPPT controller (Victron BlueSolar) is average daily output in Ahr is 33% of nameplate wattage for the panel, 25% using a PWM controller. Varies some by season, weather, length of day,....
The point of the batteries is that you have power even when the sun is down. If you want to heat the boat from battery power or have on tap hot water, it's not going to work without a lot more panels and batteries, but the rest of it should be no problem.
Figure out how much power you are actually using on average per day. You should have 3 to 4 times that amount in lead acid battery capacity. That will get you thru 3-4d with reduced solar output (overcast/rain/whatever) before the batteries are so low you might be damaging them. Whatever your capacity of battery storage you have in Ahr you should have 0.8-1.0 times that amount in Watts of solar panels.

I was also told to sail the boat around the coast with a Hydrogenerator as nothing else would really meet my needs (have you seen how much they cost?).
Hydrogenerator is way down on the list of power sources, very low bang for the buck. If I was installing EP and could pay $1k or so more for regen that would be cost effective. Otherwise start with solar. Honda Eu2200i generator. If you are in a low insolation location like the Med off season or high latitudes off season then a wind generator.

So ... sorry for the long explanation, but I would love to hear from someone that has real experience with running an office on the water so that I can try to get a system or systems working for this year.

I don't know about running an office from a boat but I installed a laser printer in my car for work. I do a lot of spreadsheets in the field and needed to print something that wasn't as touchy about rain as inkjet. The small netbook I had could run off the car battery all day. Printing had a huge draw on startup (140A) but settled down to 80-90A. Unless I wanted to print 500 pages the group 24 starting battery in my car did just fine. never had a problem starting the car afterwards.

[jen1722terry]

We manage our two summer rentals properties from our little 31-footer, using a Macbook and a mini. We also have a fridge, sometimes a fan.

Our solar is one, 160 W panel and we're in Maine.

The batteries seem to get topped up each afternoon, unless it's foggy. Even then, we get by for a day or two, then run the mill to get the batteries back up.

But we don't have a coffee maker.

Cheers

[Joh.Ghurt]

Before you go overboard and plaster your boat with solar panels, check where your point of diminishing return for solar is. At some point it's cheaper and more efficient to just start the generator for an hour or two instead of adding more panels. It isn't evil to convert diesel to battery charges every now and then when the weather was unfortunate.

Hydrogenerators work best when you're underway under sail with decent wind for long time. Are you doing this often in areas where solar is insufficient? Can you do work from the middle of the Ocean with no cellular connections? Once you know how often and long you're in such situations, again check how many hours of diesel generator you would have to use instead. If the price for the diesel is less than the price of the installation of the hydrogenerator, this isn't a solution for you.

The most ecological thing to do is not to piss away money for things you don't need. This leads to the surprising situation that 2 additional jerrycans of diesel per year are more ecological than two more panels with the matching arch, charge controller, battery etc.

[noelex 77]

Is this a system for just summer in Greece or does it have to supply power all year?

[hzcruiser]

Originally Posted by digitalnomad

I have been researching for weeks on what might be the right solution for an offgrid office on the water. [...]
Hydrogenerator as nothing else would really meet my needs (have you seen how much they cost?).

Adelie has got you pretty much covered there!

What I noticed is that you're asking for the best, best, best of _everything_ but then baulk at the price of a hydro gen? That doesn't add up, sorry.

And no, a hydro gen is of no use for an office on the water. You need lots of solar and/or a generator.

[Heathenly Twins]

I am also looking to set my boat up to work aboard. I have limited experience with running a laptop aboard but i wouldn't waste my money on AGM, gel or flooded lead acid batteries again, their performance is pretty abysmal in my opinion. Lithium batteries aren't nearly as affected by Peukert's Law and can be much more deeply discharged etc etc. I'm personally going with 400ah of lithium and as i plan to mostly just cruise in the warmer months I'll initially just rely on a high output alternator until i have a better idea of energy needs. You could always try getting a few solar panels and just setting them on deck while at anchor. This temporary solution could give you an idea of their output and from that maybe you'll get a better idea. If your primary concern is getting work done I'm sure giving up luxuries like a coffee maker will not be a big deal while you build your system up. There's always instant coffee

Oh and I don't think a Macbook is all that power hungry. Lots if YouTube vloggers spend a large portion of the day on their computers doing video editing and their electrical systems are often not very special. Sailing Magic Carpet just has one 140 watt panel and probably lead acid batteries.

Good luck!

[Viss]

I found this Delos video very helpful in determining how much power we need to plan for (also looking at a remote office situation ):

<iframe width="560" height="315" src="https://www.youtube.com/embed/uuPvhk-EP9E" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
( https://youtu.be/uuPvhk-EP9E )

We consulted a solar specialist which...we weren't impressed by as he seemed to use one template for all boats.

These solar arch guys near Lefkada in Greece were recommended to us and seemed to know their stuff, and have competitive pricing: Dimitris ( Stainless ) +30 697 3023370
They offered a smaller arch (less solar) for 1,500 EUR and a larger one (more solar) for 3,000 EUR + 500 if you want to include davits (not available for the smaller one as it would not be strong enough). This was for a 45ft boat just to give you an idea.

We were also recommended by many to put as much solar as you can and then see if it is enough. Depending on your boat it actually might be harder than you think as the 175 panels are large (and therefore need a bigger and stronger frame) and you can only fit that many on the back of the boat without it looking awful.

Good luck!