Another solar panel query!

[CJR]

Sorry 'bout this. I have trawled several threads on this but cannot find the answer i need, so here goes:

 

We want to get solar power to assist keeping the batteries topped up, but not sure how much wattage we would need. We have a widebeam so roof space not a problem, so is it better to get more than one panel or just get the biggest single panel we can get?

We are guessing at about 200w, but that's exactly it - a guess. We have 6 batteries powering all the normal stuff (lights, radio, fridge). Does this sound about right? I don't want to get too anal about power consumption - just laymans terms would be great!

We are looking at panels on ebay, direct from China - does anyone have an opinion on these? Anything to watch out for?Do we need a charge controller? Again,we have seen digital ones on ebay.

 

Any help and advice from the elecy gurus much appreciated!

[Roger Gunkel]

There are many, many in depth threads about this, which you should be able to find from the advanced search options.

 

If you are looking at keeping batteries topped up on a weekend leisure boat while you are away, the sort of power panel you are talking about may be sufficient, but if you are a liveaboard wanting to supply the majority of your power by solar, then you will need to total your expected daily power consumption, then work out what you will get from any given solar panel during the winter months on average, then multiply by your power needs and then multiply the panel requirements by the number of days you would like to have in reserve.

 

I would expect you to need at least 5 times your estimate, given a minimal power useage, and possibly considerably more for heavier use.

 

There will be others with much more knowledge to give you more accurate input soon.

 

Roger

Edited November 9, 2009 by Roger Gunkel

[CJR]

Thanks Roger.

We have shorepower at the mo, but when we go out to cruise we want to have something just to help top up the batterries if we stop in one place for a few days.

We generally get couple of days out of the batteries after a cruise if we are without shorepower. We then use a genny to top up if required.

We like the idea of using free energy (exluding the cost of the panel of course!), and not having to use the genny.

So you are really saying - the bigger the better?

Cheers

 

forgot to say - we are liveaboards.

Edited November 9, 2009 by CJR

[Tony Brooks]

Sorry 'bout this. I have trawled several threads on this but cannot find the answer i need, so here goes:

 

We want to get solar power to assist keeping the batteries topped up, but not sure how much wattage we would need. We have a widebeam so roof space not a problem, so is it better to get more than one panel or just get the biggest single panel we can get?

We are guessing at about 200w, but that's exactly it - a guess. We have 6 batteries powering all the normal stuff (lights, radio, fridge). Does this sound about right? I don't want to get too anal about power consumption - just laymans terms would be great!

We are looking at panels on ebay, direct from China - does anyone have an opinion on these? Anything to watch out for?Do we need a charge controller? Again,we have seen digital ones on ebay.

 

Any help and advice from the elecy gurus much appreciated!

 

 

I have 60 watt panel and it recharges the batteries after a weekend away and keeps them topped up during the winter with about a month or so between weekends away.

 

If I wanted to supply all my electrical needs during the winter (instead of engine charging) I would need much, much more than what you propose.

[number four]

in basic terms without getting into power audits etc.

 

if you dont have any solar or are up grading from somthing verry small

then i would recomend you get an mppt (read up on this)regulator and get the bigist one you can aford.

this will alow you to expand the sistem and give the best performance.

if you have all the normal livabord stuff then you proberly even on a wide beem will not have enough roof space to meet all your needs full time.

to keep up with a fridge spring summer autum you would want verry laymans terms 200w

 

so the answer is get the regulator and keep buying pannels till the roof is full

or you run out of money.

buy a good brand name pannel then it may cost a bit more but you should get a reliable pannel and it is easy to match up as you add on.

try and find some way of proping up the pannels to face the sun.

the maths still says that if you have mains hook up is still cheper to go thay way.

 

i am building a 45'x12' barge for liveabord with washing machin, dishwasher, microwave. we are putting 1kw of pannels and expect it to cover everything for 3/4 of the year. (with luck)

[Gunna Do]

Sorry 'bout this. I have trawled several threads on this but cannot find the answer i need, so here goes:

 

We want to get solar power to assist keeping the batteries topped up, but not sure how much wattage we would need. We have a widebeam so roof space not a problem, so is it better to get more than one panel or just get the biggest single panel we can get?

We are guessing at about 200w, but that's exactly it - a guess. We have 6 batteries powering all the normal stuff (lights, radio, fridge). Does this sound about right? I don't want to get too anal about power consumption - just laymans terms would be great!

We are looking at panels on ebay, direct from China - does anyone have an opinion on these? Anything to watch out for?Do we need a charge controller? Again,we have seen digital ones on ebay.

 

Any help and advice from the elecy gurus much appreciated!

 

I have a 85w panel from china £195, which I cannot distinguish from a lot of the UK offerings. I think that they must also get chinese units and sell them on!

I was a little concerned at first but as I got mine on E-Bay, I checked the feedback system which was 100% so decided to go ahead. Arrived well packed after about 4 weeks. I am contemplating about getting another so that I can twin them up. I think this seller's ebay name was 'Tiffanywatch' if my memory serves me correctly. Roll on the day when we can get a new memory from china as well!

[CJR]

i am building a 45'x12' barge for liveabord with washing machin, dishwasher, microwave. we are putting 1kw of pannels and expect it to cover everything for 3/4 of the year. (with luck)

 

 

So are you building your boat out of solar panels???!!

 

Our main usages are the fridge and 20" colour LCD TV. If we use the washing machine we either have shorepower or run the engine/genny. So d'you reckon a 200w+ would do the job?

[number four]

So are you building your boat out of solar panels???!!

 

Our main usages are the fridge and 20" colour LCD TV. If we use the washing machine we either have shorepower or run the engine/genny. So d'you reckon a 200w+ would do the job?

 

at a gess if you want to feel smug about it an mppt charger and 400w that should remove disapointment and actualy acheeve something.

also may give an extra day between gen/engin runs in the summer.

[CJR]

at a gess if you want to feel smug about it an mppt charger and 400w that should remove disapointment and actualy acheeve something.

also may give an extra day between gen/engin runs in the summer.

 

 

sorry - not trying to be smug there. Came across wrong when writing....

[number four]

sorry - not trying to be smug there. Came across wrong when writing....

 

dont apoligise it made me

you my be right

[g-man]

Sorry 'bout this. I have trawled several threads on this but cannot find the answer i need, so here goes:

 

We want to get solar power to assist keeping the batteries topped up, but not sure how much wattage we would need. We have a widebeam so roof space not a problem, so is it better to get more than one panel or just get the biggest single panel we can get?

We are guessing at about 200w, but that's exactly it - a guess. We have 6 batteries powering all the normal stuff (lights, radio, fridge). Does this sound about right? I don't want to get too anal about power consumption - just laymans terms would be great!

We are looking at panels on ebay, direct from China - does anyone have an opinion on these? Anything to watch out for?Do we need a charge controller? Again,we have seen digital ones on ebay.

 

Any help and advice from the elecy gurus much appreciated!

 

I'd advise saving your money and waiting till spring before installing them. You'll get minimal useful charge from 200w panels at this time of year. Personally I've found them very good during the summer for trickle charging over a week when I'm away but now autumns arrived they barely register a charge.

 

If your heart is set on buying them then get as many as you can afford possibly upwards of 1000w but still expect to have to use a genny to charge the batteries most days.

 

Using the practical knowledge I've aquired If I could afford a decent sized solar array I still wouldn't buy... I'd put the money in stocks and shares and spend the interest earned on petrol or diesel.

[number four]

I'd advise saving your money and waiting till spring before installing them. You'll get minimal useful charge from 200w panels at this time of year. Personally I've found them very good during the summer for trickle charging over a week when I'm away but now autumns arrived they barely register a charge.

 

If your heart is set on buying them then get as many as you can afford possibly upwards of 1000w but still expect to have to use a genny to charge the batteries most days.

 

Using the practical knowledge I've aquired If I could afford a decent sized solar array I still wouldn't buy... I'd put the money in stocks and shares and spend the interest earned on petrol or diesel.

 

up round the 1000w you would only need to look els wear for power in the winter and have more than you need for the summer.

i will be using a 12v emersion heater in the summer to store the excess energy in the hot water tank.

[g-man]

up round the 1000w you would only need to look els wear for power in the winter and have more than you need for the summer.

i will be using a 12v emersion heater in the summer to store the excess energy in the hot water tank.

 

Oh I agree, in the summer months 1000w would be very useful on most days. My warning about installing panels now is that the OP would find they are not enough for their needs over the next 6 months, they'll just be sitting on the roof gathering dust.

[number four]

Oh I agree, in the summer months 1000w would be very useful on most days. My warning about installing panels now is that the OP would find they are not enough for their needs over the next 6 months, they'll just be sitting on the roof gathering dust.

 

i agree and prices are only coming down i am wating till the end of my build till i buy

[Roger Gunkel]

i am building a 45'x12' barge for liveabord with washing machin, dishwasher, microwave. we are putting 1kw of pannels and expect it to cover everything for 3/4 of the year. (with luck)

 

If you are seriously intending to use those items that you have listed on a regular basis, plus the other usual items, pumps, lights, TV, laptop etc, I would relook at your figures and be prepared to increase your panel output to a size considerably larger than you anticipate.

 

If you use the search, you will find a list of monthly output figures from a forum member regarding their substantial solar bank and wind generator output.

 

I think it is 'JUSTME', on their profile they list their equipment as:-

 

1200watts solar at up to 120vdc

FX80 solar controller

Victron 12v 3000w 120amp

200w (250w peak) 12v turbine as a tester

6kva genny

6 x 2v cells 1550amp/h 5C

 

The figures they supply are very informative and will answer a lot of questions

 

Roger

[number four]

If you are seriously intending to use those items that you have listed on a regular basis, plus the other usual items, pumps, lights, TV, laptop etc, I would relook at your figures and be prepared to increase your panel output to a size considerably larger than you anticipate.

 

If you use the search, you will find a list of monthly output figures from a forum member regarding their substantial solar bank and wind generator output.

 

I think it is 'JUSTME', on their profile they list their equipment as:-

 

1200watts solar at up to 120vdc

FX80 solar controller

Victron 12v 3000w 120amp

200w (250w peak) 12v turbine as a tester

6kva genny

6 x 2v cells 1550amp/h 5C

 

The figures they supply are very informative and will answer a lot of questions

 

Roger

 

im i right in thinking he is not on a boat?

i am limited by roof space so i get what i get.

but justme set up is almost what i have in mind for my boat.

[Justme]

Yep its me & yes I am not on a boat.

 

But my set up is to my mind very typical of what you would get if you were on a boat.

 

I dont have a perfect site just as you wont always be able to moor in one.

I have (well had now) a to shallow pitch just like a boats roof

I am not pointing due south just like you wont be as you are stuck with what ever way the canal is pointing.

 

I have day by day stats from Dec 08.

Edited November 9, 2009 by Justme

[Lesd]

we have 260w of panels and during the summer we very rarely have to run the engine or genny, this summer it was something like 6 or 7 weeks a couple of times without starting the engine and batteries never below 50% and virtually daily ack upto 100%. Thhe trick is aligning them as best you can, that makes a huge difference.

In the winter, forget it, next to nothing in real terms. We're running the genny every other day now.

Les

[Justme]

we have 260w of panels and during the summer we very rarely have to run the engine or genny, this summer it was something like 6 or 7 weeks a couple of times without starting the engine and batteries never below 50% and virtually daily ack upto 100%. Thhe trick is aligning them as best you can, that makes a huge difference.

In the winter, forget it, next to nothing in real terms. We're running the genny every other day now.

Les

 

 

Without knowing how much power you use saying you dint need the genny for 6-7 weeks does not really help. If I only used 0.5kwh per day I would not need the genny now but as I use 2-3kwh per day in winter I need the genny every 4 days or so.

 

Oh & badly alligned arrays dont make as big a difference as you would think due to the sun moving unless you have a tracker or move it every hour or so. An array aligned to far west say will make less in the morning but more in the afternoon. As long as you are not miles out you will be ok.

[Phil Ambrose]

Thanks Roger.

We have shorepower at the mo, but when we go out to cruise we want to have something just to help top up the batterries if we stop in one place for a few days.

We generally get couple of days out of the batteries after a cruise if we are without shorepower. We then use a genny to top up if required.

We like the idea of using free energy (exluding the cost of the panel of course!), and not having to use the genny.

So you are really saying - the bigger the better?

Cheers

 

forgot to say - we are liveaboards.

 

If it helps, we live aboard and have 5 X 100 watt panels which do supply all our needs in summer but falls short in the winter. We run 12v fridge, 12v freezer a 3kw inverter running TV, microwave on occasion. Battery bank of 7 X 110a/h plus starter.

 

Phil

[Chris Pink]

i am building a 45'x12' barge for liveabord with washing machin, dishwasher, microwave. we are putting 1kw of pannels and expect it to cover everything for 3/4 of the year. (with luck)

 

I am sorry but you will never run those devices with 1KW of panels in England (unless you do the washing up once a year)

 

My answer to the OP is get 80-120W, see how you fare then adjust as necessary. With the shore power backup PV is going to be a very very expensive way of meeting a small part of your energy demand. The advice to get a bigger controller than you need is a good one.

 

200W would provide a very useful contribution to a completely off-grid, low-energy usage (unlike the example above) and would probably meet all needs for up to 6 months of the year (dependent on fridge and laptop usage) but the use of high power devices with small solar arrays is daft.

 

 

We then use a genny to top up if required.

We like the idea of using free energy (exluding the cost of the panel of course!), and not having to use the genny.

 

Just saw this which illustrates your situation, you say you have a generator, presumably 800W or more? And a rated output.

 

you can't substitute that with 200W of solar when the only time you'll get your 200W is on a bright sunny day.

[number four]

I am sorry but you will never run those devices with 1KW of panels in England (unless you do the washing up once a year)

 

My answer to the OP is get 80-120W, see how you fare then adjust as necessary. With the shore power backup PV is going to be a very very expensive way of meeting a small part of your energy demand. The advice to get a bigger controller than you need is a good one.

 

200W would provide a very useful contribution to a completely off-grid, low-energy usage (unlike the example above) and would probably meet all needs for up to 6 months of the year (dependent on fridge and laptop usage) but the use of high power devices with small solar arrays is daft.

 

 

 

 

Just saw this which illustrates your situation, you say you have a generator, presumably 800W or more? And a rated output.

 

you can't substitute that with 200W of solar when the only time you'll get your 200W is on a bright sunny day.

 

i did not explane how much crusing i would be doing.

or how i manage my use of high load equipmet to make the best of things.

(we have lernt to reduce the load on the bats by at least 1/2 i would say by good practis when crusing in the 5years we have lived abord)

you have asumed that i will spend all my time in one spot and never use the motor , which is odd on this forum the norm should be a travling boat

but

justme is the exception to prove the rule.

 

how my washing machine and dishwasher is set up and the amount of power they will use is another subject (do a serch)

 

the op did not want detale but a rule of thumb i know what everyone sayes but he did not want a lecture

 

if you think 200w meets all your needs part of the year then what do you think 5x that will do?

 

perhaps it might have been better if the op had given a budjet and what his expetations were in more detail

but hay ho it gives us something to do on a rainey day (abusing the bats )

 

for me solar is a one of cost with almost no maintance

desel is a fuel that is only going up in cost and is high cost high maintance sorce of power.you allso have to expend desel to go and get more,you have to be in atendance to use it

solar has lots of unseen advantages for a crusing boat.

the bottom line is build a system that fits you own needs and values.

[CJR]

If it helps, we live aboard and have 5 X 100 watt panels which do supply all our needs in summer but falls short in the winter. We run 12v fridge, 12v freezer a 3kw inverter running TV, microwave on occasion. Battery bank of 7 X 110a/h plus starter.

 

Phil

 

That gives us a good yardstick - thanks.

 

p.s. Good to hear you are still getting lots of sun on the Broads - we miss it there. Whereabouts are you on the broads? We used to live in Ludham.

[CJR]

My answer to the OP is get 80-120W, see how you fare then adjust as necessary. With the shore power backup PV is going to be a very very expensive way of meeting a small part of your energy demand. The advice to get a bigger controller than you need is a good one.

 

200W would provide a very useful contribution to a completely off-grid, low-energy usage (unlike the example above) and would probably meet all needs for up to 6 months of the year (dependent on fridge and laptop usage) but the use of high power devices with small solar arrays is daft.

 

Just saw this which illustrates your situation, you say you have a generator, presumably 800W or more? And a rated output.

 

you can't substitute that with 200W of solar when the only time you'll get your 200W is on a bright sunny day.

 

Out of interest, do laptops use much power?

It would really only be the spring/summer months that we would expect to get any real power out of the panel, as that is when we are not on shorepower and are cruising around.

We have a 2kw honda genny which is great, but depending on where we are on the system, we may well run out of petrol and not be near any civilisation to get any more!

[alan_fincher]

Out of interest, do laptops use much power?

Modern ones with lo's of inbuilt stuff and big screens can be surprisingly power hungry.

 

The 17" screened Dell I'm using here is marked up as 19.5 volts at 4.62 amps. That's presumably running flat out, but equates to a fairly massive 90 watts.

 

To derive the 90 watts from 12 volts, could mean drawing 7.5 amps from your batteries, even if your "inverter" process is 100% efficient, (and 90% efficient is more likely, so 8 amps plus).

 

That said, you can always tune them to have screen less bright, disk and optical drives powering down when not in active use, wireless turned off, etc, and in my experience current drain will be a lot less.

 

But unless you buy something very small and portable, bargain on perhaps 4 amps at 12 volts, which makes it as thirsty as a fridge, when actually running, (plus it's on all the time, not cycling on and off like a fridge does). No real problem, unless you have it on all day, when it can become a major part of your total electricity usage, (in my experience).

 

(Or simply boat most days, then it's not a problem!).