Solar panels (again, sorry!)

[tomandsophie]

Wow, that's a heck of a lot less than I was expecting. Ah well, looking forward to summer...

 

Wind turbine on its way next then

[Gary Peacock]

I hope I'm wrong but having spent the last few days sourcing various panels and charge controllers and looking at the outputs and the initial outlay I couldn't help thinking "Why Bother!" even the best designed more expensive set ups don't seem to make financial or economical sense without they are used over a very long period to recover the initial investment before they move into actually saving money used on alternative power sources.

 

Saying that if you have deep pockets and can afford to be green I don't have a problem with the morals of that, but is that what it's really about rather than free energy for those with sensible boats and realistic energy consumption for the more average life style?

Edited January 17, 2007 by Gary Peacock

[Nemesis]

I hope I'm wrong but having spent the last few days sourcing various panels and charge controllers and looking at the outputs and the initial outlay I couldn't help thinking "Why Bother!" even the best designed more expensive set ups don't seem to make financial or economical sense without they are used over a very long period to recover the initial investment before they move into actually saving money used on alternative power sources.

 

Saying that if you have deep pockets and can afford to be green I don't have a problem with the morals of that, but is that what it's really about rather than free energy for those with sensible boats and realistic energy consumption for the more average life style?

Gary,

I came to a similar conclusion.

I can see them being useful for keeping batteries topped up over the long term if a boat is moored up and not in general use and has no access to shore power.

For general day to day use on a boat that is inhabited, I don't believe they generate enough power to be of any great worth (especially at the price they are currently sold at).

[tomandsophie]

Ok, so if I want to add a wind turbine as well, do you know if I can add another charge controller and just wire it in to the batteries separately, or do I have to take out the one for the panels and replace it with one that'll handle both?

[Gibbo]

Ok, so if I want to add a wind turbine as well, do you know if I can add another charge controller and just wire it in to the batteries separately, or do I have to take out the one for the panels and replace it with one that'll handle both?

 

You can keep the existing one there and add the wind turbine and it's controller. They *usually* come as a package and some have the controller built in.

 

Don't be too disillusioned. In summer you will get some worthwhile power.

 

As an aside, and as I've said many times in the past, solar power in the UK, with current prices, will never make financial sense. Solar panels, like anything else, have a finite life and they will have reached this life limit before they have paid for themselves. Until someone comes up with a vastly more efficient solar panel this will remain to be the case. Of course if you have no other form of power then this argument means nothing.

 

Gibbo

[magnetman]

I have done some calculations comparing the use of solar from April-September with the use of a small petrol generator and I came to the conclusion that they (2x75w monocrystalline PV's) save around £80-£100 per year of petrol (that was @80p/litre).

£700 for the two panels makes this a 7-9 year payback time. Cost effectiveness is related directly to alternatives. Obviously mains is going to remain cheaper as it is effectively 'mass produced energy' but for someone without a mains connection solar is a good option. Mount the panels on an adjustable frame and point it south angled at midday sun for maximum effectiveness. In winter angling at the sun is even more important, obviously and a good sunny winter day can result in quite a nice charge.

 

To me, personally, its not about being 'green' or 'saving the planet' thats all a bit airy to me but rather about additional energy sources which makes me more independent and not tied so firmly to a fuel pump.

[alan_fincher]

T&S

 

If you haven't already, it might be worth you exchanging messages with Carrie on this topic.

 

In fact her latest blog posting, (on this site), details her experiences to date with solar panels.

 

Hers sound to be slightly higher output than yours, and she reports her lowest output from as only about 4-6 Ah per day on the dullest of days.

 

As I'm assuming you had a very grey and miserable day like us yesterday, it sounds like what you have managed is of the same order, (especially if hers are supposed to be marginally more powerful).

 

It's also in line with peoples calculations, so I rather expect that other than experimenting with exactly where you have them pointed, they are probably working as expected.

[Gibbo]

I have done some calculations comparing the use of solar from April-September with the use of a small petrol generator and I came to the conclusion that they (2x75w monocrystalline PV's) save around £80-£100 per year of petrol (that was @80p/litre).

£700 for the two panels makes this a 7-9 year payback time. Cost effectiveness is related directly to alternatives. Obviously mains is going to remain cheaper as it is effectively 'mass produced energy' but for someone without a mains connection solar is a good option. Mount the panels on an adjustable frame and point it south angled at midday sun for maximum effectiveness. In winter angling at the sun is even more important, obviously and a good sunny winter day can result in quite a nice charge.

 

To me, personally, its not about being 'green' or 'saving the planet' thats all a bit airy to me but rather about additional energy sources which makes me more independent and not tied so firmly to a fuel pump.

 

I'd question your maths on that. Can you run through the figures. Then add on the cost of the generator and maintenance.

 

Gibbo

[magnetman]

OK. this is not provable but my experience and an estimation.

 

average daily input from 150w of PV from April-september is around 20Ah. Sometimes much more sometimes less.

 

petrol genny/ 12v 16A charger using 0.5 litres/hour = 0.625 litres at 80p/litre to do 20Ah.

 

50p a day estimated fuel costs.

 

180 days that's £90 I don't have to spend on petrol.

 

£90 a year to pay for £700 of panels is basically 8 years.

 

OK so thats an inefficient genny/charger but a new genny and/or charger is a capital expense and would always COST money and not SAVE it.

 

As I do not have an Ah counter I can't verify total input and my 20Ah per average day is quite probably complete ****.

[Gibbo]

OK. this is not provable but my experience and an estimation.

 

average daily input from 150w of PV from April-september is around 20Ah. Sometimes much more sometimes less.

 

petrol genny/ 12v 16A charger using 0.5 litres/hour = 0.625 litres at 80p/litre to do 20Ah.

 

50p a day estimated fuel costs.

 

180 days that's £90 I don't have to spend on petrol.

 

£90 a year to pay for £700 of panels is basically 8 years.

 

OK so thats an inefficient genny/charger but a new genny and/or charger is a capital expense and would always COST money and not SAVE it.

 

As I do not have an Ah counter I can't verify total input and my 20Ah per average day is quite probably complete ****.

 

Right I'm with you now.

 

I think the 20Ah per day is probably a good "guesstimate".

 

That *is* an inefficienct genny/charger. 0.5 litres per hour is a lot of petrol for a 16A charger. 0.5 L/h should get you closer to 30A. So that instantly doubles your payback time.

 

The other problem is that the output of solar panels falls as they age until it reaches about 25% after 25 to 30 years. After 15 years they will be down to around 50% of their original output. Redo the sums now and you'll see it isn't quite so rosy. I did have some online references for this but I can't find them.

 

Of course it's nice that you don't have to mess around with a generator but the financial side, at the moment, just doesn't make any sense. It *will* do when PVs become more efficient (which they *must* do one day) and the price falls further.

 

Gibbo

[tomandsophie]

The way I see it is that the panels cost me £550 in total (including controller, wiring, and all that stuff). If we can get ourselves a wind turbine and cover all our power usage (which we should be able to do, as a lot of my fellow boaty friends have done with similar systems to ours), then our costs will total around £1100 (Rutland 913 + controller at £550 ish).

We burn £30 worth of diesel a month to generate our electricity. That's roughly £360 a year. So three years and that's the panels and turbine totally paid for.

 

 

 

The other problem is that the output of solar panels falls as they age until it reaches about 25% after 25 to 30 years. After 15 years they will be down to around 50% of their original output. Redo the sums now and you'll see it isn't quite so rosy. I did have some online references for this but I can't find them.

 

 

 

Our panels have a 20-year guarantee, as do most of the good quality ones. So perhaps we should keep our receipts totally safe and refer back to them in 19 years time!

Edited January 17, 2007 by tomandsophie

[Gibbo]

The way I see it is that the panels cost me £550 in total (including controller, wiring, and all that stuff). If we can get ourselves a wind turbine and cover all our power usage (which we should be able to do, as a lot of my fellow boaty friends have done with similar systems to ours), then our costs will total around £1100 (Rutland 913 + controller at £550 ish).

We burn £30 worth of diesel a month to generate our electricity. That's roughly £360 a year. So three years and that's the panels and turbine totally paid for.

 

If you're using £30 of diesel per month to generate your electricity then assuming a normal size alternator, engine, batteries etc. then you are using *far* more electricity than you are ever going to generate with your solar panels and a 913 wind turbine. Unless you quadruple the size of your solar panels and put four wind turbines up. Which of course means you spend four times as much.

 

 

Our panels have a 20-year guarantee, as do most of the good quality ones.

 

Why do you think they chose 20 years? Perhaps something to do with the lifespan of solar panels?

 

 

So perhaps we should keep our receipts totally safe and refer back to them in 19 years time!

 

LOL. Worth a try I suppose.

 

Gibbo

Edited January 17, 2007 by Gibbo

[magnetman]

Why do you think they chose 20 years? Perhaps something to do with the lifespan of solar panels?

LOL. Worth a try I suppose.

 

Gibbo

 

Ok so they are not cost effective but I do like a proper silent generator...

 

20 years guarantee. supplier will be out of business in 20 years anyway and normally its 'guaranteed to produce 80% rated output for 20 years".

I have bought solar panels already so its too late and I have to defend them for the sake of my own self worth. I quite like them but they don't do that much and do take ages to pay back.

What's this 30A charger I can run on my EX650?

[Gibbo]

Ok so they are not cost effective but I do like a proper silent generator...

 

20 years guarantee. supplier will be out of business in 20 years anyway and normally its 'guaranteed to produce 80% rated output for 20 years".

I have bought solar panels already so its too late and I have to defend them for the sake of my own self worth. I quite like them but they don't do that much and do take ages to pay back.

What's this 30A charger I can run on my EX650?

 

I'd love to have some solar panels because the idea is great. It's the cost of them that messes it up. They're simply too expensive for the amount of power they produce. But the price is falling all the time as more people buy them. Maybe in another few years they'll be worthwhile. Wind turbines make much more sense to my mind.

 

Speak to Sterling. Their 40 amp pro-digital charger has something called active power factor correction. It doesn't matter whether anyone here knows what it is. It means it will run from a much smaller genny than most people think. A 30 amp charger with PFC would run from that 650 genny, Sterling's might just do it. Ask them.

 

Gibbo

[Bones]

I have solar panels out of sheer laziness.. I don't want to remember when to run my engine to charge the batteries, I would much rather just monitor them and ensure they are ok. I also don't use very much electricity at the moment - I use one light and that takes up very little power, and my water pump seems quite tame. I run my fridge on mains (I think that cost me 9pounds last quater). I am hoping to be able to run the fridge off the panels in summer and I simply won't use it in winter when I am not near mains.

 

I am looking forward to seeing how the solar panel comapares to the wind generator which was on the last boat I lived on.

 

I also don't like the sound of the engine running to charge the batteries.. nor do I like it when other people do the same. It spoils the peace and quiet!

Edited January 17, 2007 by Bones

[DHutch]

I'd love to have some solar panels because the idea is great. It's the cost of them that messes it up. They're simply too expensive for the amount of power they produce. But the price is falling all the time as more people buy them. Maybe in another few years they'll be worthwhile. Wind turbines make much more sense to my mind.

Yeah, im the same.

- As said, they do have there uses. As ive said before, we have two 20w pannels, which we intend to wire up for a bit of fun, and maybe to float-charge the batterys while the boat unattended.

- But when you look at the prices, and the output specs, in terms of generating real power a rutland 913 is streaks ahead of any solar pannel ive yet to see!

 

 

Daniel

[magnetman]

Speak to Sterling. Their 40 amp pro-digital charger has something called active power factor correction. It doesn't matter whether anyone here knows what it is. It means it will run from a much smaller genny than most people think. A 30 amp charger with PFC would run from that 650 genny, Sterling's might just do it. Ask them.

 

Gibbo

 

I may well do that... Thanks.

As for wind turbines, yes, you need to be somewhere with a nice 'clean' wind regime, an obvious but often overlooked factor. I suspect that the 'X&Z' hardware chain is going to be responsible for a lot of disillusioned 'green people' who despite their politically correct beliefs will continue to leave the telly, video, dvd, sat box, cable box, computer, other computer, printer, wireless device, toaster, and washing machine on standby.

 

I have a feeling that as energy costs increase so will the cost of solar panels, as they are simply an energy source.

 

Why is it that all of the best electrical generators get sent up thousands of miles vertically on rockets?.

 

edit: I want one of these:

http://en.wikipedia.org/wiki/Radioisotope_...ctric_generator

Edited January 17, 2007 by magnetman

[chris w]

I've only just read today's posts on this, so apologies for being tardy.

 

The payback period would be a lot longer than 8 years because over such a time period you would have to take the time-value of money into account at, say, a conservative 10% to produce a discounted cash flow. The true payback period would be around 13 years which probably puts the panels right out of ballpark from a financial standpoint.

 

Chris

[magnetman]

I've only just read today's posts on this, so apologies for being tardy.

 

The payback period would be a lot longer than 8 years because over such a time period you would have to take the time-value of money into account at, say, a conservative 10% to produce a discounted cash flow. The true payback period would be around 13 years which probably puts the panels right out of ballpark from a financial standpoint.

 

Chris

 

Good point. Fuel costs and uncertainty of supply might affect the overall position as well.

edited

Edited January 17, 2007 by magnetman

[tomandsophie]

If you're using £30 of diesel per month to generate your electricity then assuming a normal size alternator, engine, batteries etc. then you are using *far* more electricity than you are ever going to generate with your solar panels and a 913 wind turbine.

 

How much do most people use? I don't have a TV, so all we run off our batteries is usually about 40w of lights (although with our new LEDs this will soon be much less, more like 4w), a car stereo, water pumps, and a 12v laptop charger. To keep our batteries above 12v we have to run our enging (Beta 43 with 95a alternator) for 1 hour each night. At 2 litres/hour this works out at roughly 60 litres a month. With red diesel at the moment costing 60p/litre, that is £36 a month. Of course sometimes we're not at home in the evening, so this figure is generally more like £30. Doesn't that sound about right? I thought we used a lot less power than most people (with all their fancy TVs and DVD players and so on).

[alan_fincher]

T&S

 

If you are just running your engine to charge batteries, I'm kind of surprised you think you are using as much as 2 litres per hour.

 

When cruising most engines will do better than this - our elderly BMC 1800 gives no worse than 1.5 litres an hour, and people with more moderm engines report even better.

 

I can't see why you would need to be using fuel faster when static than when moving.

 

How big is the engine, and how hard are you running it ?

 

Are you confident about that consumption figure ?

[tomandsophie]

Alan,

The engine is a two-year-old Beta Marine Greenline 43hp. The consumption figure is off their website. Having said that, the graph isn't very clear, so perhaps the 2l/hr figure is a bit high. To be honest I'm not that sure. But it does tend to average out around £30 a month ish.

[John Orentas]

Hi T & S

 

You are running a 33 Kw engine to generate probably less than 1 Kw of energy. That is about the least efficient machine that could be devised. The vast majority of the engine power when running in this way will be taken up in keeping itself warm, overcoming it's own internal friction and generally heating up the canal. If that is not enough you are progressively wearing out a very expensive engine.

 

Just about any generating system you could think of will be more cost effective than what you are using now.

[tomandsophie]

John, I am sure you are right. We are doing our best to find an alternative quickly. The best alternatives as far as we can see are solar + wind, and perhaps a small petrol genny + charger for topping up.

 

One thing I don't understand about the panels though is this: When I went home at lunchtime yesterday, it was partly cloudy and the panels were putting out 5 amps. When I got home in the evening though, the total charge current recorded for the day was 7ah. If the panels put out 5 amps for, say, 3 hours or so, surely we should get more like 15ah?

Edited January 18, 2007 by tomandsophie

[John Orentas]

Just been watching a silly programme on TV but it included a piece about a chap with a very posh holiday home.

 

He had installed a few solar panels, didn't say how many but each about 6 x 1.5 ft. Plus a wind generator, looked like one of those B & Q ones. What actually caught my attention was that the bloke said he has got a £500 grant from the government. That did not sit well with me somehow, I think a better use could be found for £500