How Much Solar

[belizesailor]

Originally Posted by foggysail

G... Places such as Florida are overwhelmed with the sun whereas here in Massachusetts there are always some clouds and many of them from airplanes, yes airplanes....

Yes, latitude in particular is an important factor. Technically you should adjust the angle of your panels based upon your latitude for optimal performance. Should also adjust to a lesser extent for seasonal variation.

Easy to do here at home, panels are mounted on a pole with an adjustable frame. A bit more challenging on a boat.

Here at about 15.756N we get plenty of sun most of the year, but lightly overcast days are not uncommon during the raining season (now).

At the house I'm running two 185W panels and a Morningstar controller. Our biggest loads are refrigeration (12V) and laptop computers followed by water pumps. All 12V LED lighting so very minimal draw. This meets our needs during the day even on partly cloudy days (like today -- light overcast), but I usually give the battery bank a little bump with the generator in the early evening just to make sure, but its not always really necessary (the house bank is getting a little old too which doesn't help). 30 minute to 1 hour run using a Xantrex 45A charger going to a 450AH bank (4 x 6V @ 225AH). The charger usually steps down to 20A a few minutes into the run and I usually shut it down after it steps down to 10A.

Usage note on computers: When we are just hanging out in the off season, our PC usage goes up and accounts for our largest load during the day. Monitor the amp usage on one of these little beasties with a meter sometimes -- you will be shocked! Going the typical route of inverter to power adapter to PC makes it worse because this is very inefficient. And, most of their power adapters will continue to draw some juice even when there is no load -- PC disconnected. Much less draw to just charge battery when PC is turned off.

Aboard the boat we use much less juice because laptops are not running as much (much healthier to be out snorkeling anyway!). Only have about 150W on the boat now, but plan to upgrade in the near future. Similar routine there in terms of solar/generator use.

[onestepcsy37]

we have a 37 foot cutter which we cruise in florida and the bahamas.

one kyocera 135 watt solar panel, four golf cart batteries (450 ah), and a stand alone 35 amp battery charger run by a honda eu1000. no wind charger (too complex for me).

biggest draw is the adler barbour fridge - maybe 40ah a day now that we've cut down the size of the fridge with insulation to a more suitable 3.5 cu ft. all other draws are intermittent like lights, fresh water pump, vhf. we are not overly equipped with electronics. except the cpt autopilot, which draws only when we're making day long or longer passages.

at anchor the panel will give us about 40-50 amps a day, which pretty much runs the fridge. long experience has shown that i need to run the honda/charger every third day for a few hours, using about a quart of gas. i run it till it is out of gas so i can store it below in the lazarette - by that time the 35 amp charger is down to putting about 10 amps in the batteries. then we're free for the next three days.

i intend to add a second kyocera 135 watt solar panel. when i do that i expect i may never have to run the generator again.

[laforge24]

Also keep in mind that the amount of solar is related to the batteries volume(Ah); trying to charge 400Ah batt. with 100Wsolar is not going to work, reversed the same 100Ah batt, charging with 400Wsolar the batt. will be quickly charged. On a beginners system you can always add more panels or even a windgenny. but if you start off with a 200Ah batt, you CANNOT just add another 200Ah, difference of age/make/charge will make them not last long.
So how much space has your boat for a proper batt.bank without dropping the waterline?
240Wsolar 'can' supply 20A charge, problem mostly is coverage of the panels by sail/beam/mast and clouds, out of an 8hr day we get max 5 optimum hrs
ie; 100Ah.
Boats are a limited space, I would go for the combination of solar and wind,
on the day that is cloudy and grey, there is wind,
the Air marine supplies 300W max with peaks weigh higher, fuse=100a?
and is a lot cheaper than solar. and works 24hr/day
run laptop on 12volt, converting has enormous losses

[denverd0n]

Originally Posted by mrm

If you don't know your daily consumption or can't be bothered with math the answer is even simpler: install what you can afford and have space for and live with it.

BINGO!

The effort is minimal and the math is simple to do pretty accurate demand calculations. But if you can't be bothered then just buy whatever you can afford, or whatever seems to fit, and live with it. How hard is that?

[s/vPainkiller]

Guys, the OP stated that he DID the calculations. So please stop berating him about how simple it is, and if he can't be bothered, etc. He simply asked for real life examples of what people are experiencing.

I, for one, like the question and would like to hear responses without the chiding. Thanks to those of you who answered with your experience.

Scott

[Azul]

Since this thread is aimed at off-grid newbies like me, some of the present formulations I have read in this thread seem controversial based on what I have read elsewhere. First, using your diesel engine to charge the house bank is hard on the diesel as they do not like to be run without a load or for that matter even below optimal rpm. Second, many people consider wind generators too noisy, expensive, unaesthetic and unreliable since panels have become relatively inexpensive. Third, while the very quiet and familiar to many Honda 2000eu generator is fuel efficient and reliable- there is the worry of having gasoline on board and the unit costs $1100 and may require going on deck to crank it up to make a cup of coffee. Seems like it would be better to spend the $1100 on a basic solar system. Fourth, and a point the OP implies is that many of us find it tedious to research what each individual electrical item on board draws from potentially unreliable charts, especially when we don't already own some or all of the items we plan to cruise or live with then put that spreadsheet into the simple math equation minus the latitude we cruise at, divided by the gains obtained by serial wiring vs parallel and multiplied by the dangle angle subverted by the shade factor corrected by the $600 MPTT. What I have learned so far this thread: a Fridge is going to eat up roughly one 185 watt panel, and the analytical types that view planning a solar battery charging setup with the same fervor involved in planning a moon mission like to make calculations rather than give simple starting "real world" advice aside from "buy what you can afford." Can someone suggest a modular "starter" system complete with links to cost effective components that can be easily upgraded? For example, if you buy two batteries, can't you later buy two more and wire each set parallel and use them as battery bank one and battery bank two? Can someone share a AH usage chart that they have made up divided into musts and "nice to haves" like reefers, radar etc?

[laforge24]

What is not mentioned here, or not directly, is the quality of the system !!! there are polychrystaline and monocrystaline, look at their 'open'output(V) buy a regulator with overcapacity so you can add a panel and don't have to change the regulator,
the wiring should be overdimensioned(low V=high A) loss on cables/connecters,
the current on the batt.connections creates heat if not well fastened due to too many wires, Solar works for free, if you monitor it well !!

[LakeSuperior]

Originally Posted by Azul

What I have learned so far this thread: a Fridge is going to eat up roughly one 185 watt panel, and the analytical types that view planning a solar battery charging setup with the same fervor involved in planning a moon mission like to make calculations rather than give simple starting "real world" advice aside from "buy what you can afford." Can someone suggest a modular "starter" system complete with links to cost effective components that can be easily upgraded? For example, if you buy two batteries, can't you later buy two more and wire each set parallel and use them as battery bank one and battery bank two? Can someone share a AH usage chart that they have made up divided into musts and "nice to haves" like reefers, radar etc?

Can't have it both ways my friend...first you want simple, no moon mission planning, a little hip check to the pocket protector types, and then in the next breath you want someone to engineer a complete system. On top of that you want someone to give you arbitrary AH chart with the musts and nices seperated in colored columns. I don't think the simples put those kind of chart together or at least I won't trust them. Why not press the simple button and just buy some stuff and hook it up?

It sounds like the OP got the system and performance he paid for.

[noelex 77]

Solar systems can be a little hard to upgrade for few reasons.

1. Wiring, changing is expensive.
2. Controller. Large controllers are expensive, but buying a small one and later buying a large one is even more expensive.
3. Panels. Often the designs change. Arches or biminis designed for a specific panel may not accommodate the new model. With MPPTcontrollers the panels need to kept similar at least in Vmpp.

IF you are not sure of equipment draw ask, someone will know, but the best advice I have seen is carefully calculate your consumption, but then fit the most watts you have room for regardless of the calculations.

[laforge24]

Originally Posted by Azul

Since this thread is aimed at off-grid newbies like me, some of the present formulations I have read in this thread seem controversial based on what I have read elsewhere. First, using your diesel engine to charge the house bank is hard on the diesel as they do not like to be run without a load or for that matter even below optimal rpm. Second, many people consider wind generators too noisy, expensive, unaesthetic and unreliable since panels have become relatively inexpensive. Third, while the very quiet and familiar to many Honda 2000eu generator is fuel efficient and reliable- there is the worry of having gasoline on board and the unit costs $1100 and may require going on deck to crank it up to make a cup of coffee. Seems like it would be better to spend the $1100 on a basic solar system. Fourth, and a point the OP implies is that many of us find it tedious to research what each individual electrical item on board draws from potentially unreliable charts, especially when we don't already own some or all of the items we plan to cruise or live with then put that spreadsheet into the simple math equation minus the latitude we cruise at, divided by the gains obtained by serial wiring vs parallel and multiplied by the dangle angle subverted by the shade factor corrected by the $600 MPTT. What I have learned so far this thread: a Fridge is going to eat up roughly one 185 watt panel, and the analytical types that view planning a solar battery charging setup with the same fervor involved in planning a moon mission like to make calculations rather than give simple starting "real world" advice aside from "buy what you can afford." Can someone suggest a modular "starter" system complete with links to cost effective components that can be easily upgraded? For example, if you buy two batteries, can't you later buy two more and wire each set parallel and use them as battery bank one and battery bank two? Can someone share a AH usage chart that they have made up divided into musts and "nice to haves" like reefers, radar etc?

I think a 300Wsolar on a 400Ah batt bank sounds good, devided into two banks of 200Ah even better, what you got wrong is how to use it,
why should you need to make coffee with electricity, which is going to be 220 or 110 and thus need converter and thus create loss, just to heat up a bit of water, try to avoid the use of converters because those are bigger consumers then fridges!

[Azul]

What I am trying to say, Lake Superior, is that these threads are usually taken into the (calculation) weeds by the pocket protector types (whom I respect btw as my oldest son is at MIT) and despite 30 hours of reading on this forum I have yet to see someone suggest a BASIC starter system that is upgradeable that someone can start with and build on later without throwing what they have out. I doubt that I am the only one slightly frustrated by this.

The only one that has posted useful information in this regard is Goldiphlox, she suggested a specific inexpensive panel (89c per watt) and a specific HQRP WPM controller for $47.

[Ashura]

You should just mount as much panels thats practical and allowed in the budget.

In the end youre ultimate limiting factor will be real estate to mount the panels.

Usage loads will change. Future panels will become cheaper and more efficient. But the space to mount them will not.

I would engineer something that would allow the largest mount of panels to be mounted and wiring to support them. Installation costs shouldnt be too much more, why not plan for upgrades in the future.

Plus panels are cheap nowdays. Why not mount much as you can? Just because you might not be using them now doesnt mean you wont in the future.

[djmarchand]

I am sympathetic to the OP as there are many variables in determining electrical demand and even more variables in determining supply.

So with that said, I had about 200 watts of fixed mounted panels, sometimes partially shaded by the boom. In Florida in the winter they would supply about 2/3 of my 80 amphour daily loads with mostly sunny weather. In Maine in the middle of the summer it was about the same.

David

[LakeSuperior]

Originally Posted by Azul

What I am trying to say, Lake Superior, is that these threads are usually taken into the (calculation) weeds by the pocket protector types (whom I respect btw as my oldest son is at MIT) and despite 30 hours of reading on this forum I have yet to see someone suggest a BASIC starter system that is upgradeable that someone can start with and build on later without throwing what they have out. I doubt that I am the only one slightly frustrated by this.

I would not invest my hard earned after tax dollars on a backhanded suggestion from someone on CF. You can't expect people that don't know your equipment, needs, and use cycles to engineer a system for you on CF that you can then go and install in your boat.

It's easy and there is no downside to weighing in on CF. You don't have to pay for it and you don't have to live with it. It's someone elses problem.

Do your research first, buy an intro book, study the panel manufacturers recommendations and examples so that you understand what is needed and what each part does and how it integrates into your systems.

At this point I would go out to CF and read the history. Then I would ask for ideas, suggestions, better ways to accomplish the task, what is the newest hardware, is this the best way, etc. That is, I would get my plan validated by some of the smart folks on CF.

At that point I would put together a final plan, buy the hardware, install, and then enjoy my new capabilities.

[laforge24]

We are trying to explain what would be logically possible, not what is cheaper
buying cheapest is definitly not better especially in wet conditions,
there is affordablle, good and the best, just as with a boat