Solar Charger

[Ian]

I thought members might be interested in my solar charging rig, although given the recent weather a hydro-electric generator in the gutter down pipes may be more effective.

The rig consists of 2 18W solar panels, these provide 3 amps in bright sunlight to charge the 80Ah leisure battery, the output from which feeds a 300W inverter providing 230V for the bike charger. By using the correct charger I hope to avoid adverse effects to the bike battery. I estimate that about 2 reasonably sunny days will replenish the leisure battery after a full charge of the bike battery.

This rig has been assembled in anticipation of a forthcoming caravan holiday away from mains electricity, I'm hoping that by taking the solar rig, a couple of fully charged leisure batteries and 3 fully charged bike batteries I can be self sufficient for a couple of weeks.

 

[JohnInStockie]

Very impressive

 

[JohnInStockie]

Ian,

I live in a valley with a lot of trees on the horizon and that means little wind and less sun. But we do have a brook, and in one of my curious moments wondering if I could use something like the wheel on a small paddle boat to create energy, I found this website where someone appears to have had a similar (or actually a better) idea using water pressure (the viseo is quite explanitary).

I thought it was a good idea this guys got, but it seems that no-one is interested from the replys I have had from people in the UK.

Oh well, I'll just have to hire an allotment and raise a solar and wind 'farm'.

John

 

[flecc]

Nice job Ian. I'm sure you'll be more successful than A to B at avoiding battery ill effects. I think the characteristics of solar panels need an isolation stage, and lead acid batteries seem to be happy in that role.

I'll keep my fingers crossed that you have only sunny weeks for your forthcoming holiday. Come to think of it, caravan roofs seem to be an eminently suitable place for solar panels.
.

 

[Ian]

John,

running water, even in quite a small volume has a lot of energy and I would guess that even a simple waterwheel could generate more power than my solar panels, and whats more it would work 24/7.

A very simple low power idea would be to fix some paddles to an old hub dynamo bicycle wheel and suspend it in the brook.

 

[Ian]

I'm sure you'll be more successful than A to B at avoiding battery ill effects. I think the characteristics of solar panels need an isolation stage, and lead acid batteries seem to be happy in that role..

Thanks for your kind comments Flecc, I think A to B magazines trials were based on environmental considerations which ruled out the use of a limited life lead acid intermediary battery. Even from a financial perspective the use of a £40 battery to save perhaps £10 over it's lifespan makes no sense, however in my case I already had the battery & inverter which I have used to charge the bike on previous weekend breaks. The solar panels are an attempt to make the system work over longer breaks.

I too thought the caravan roof would be an ideal location, however experimentation has shown that positioning is critical and a horizontal position is only effective at mid-day, the position of the panels in the photo was the optimum position at 18:15 today, facing due west, so repositioning throughout the day is important.

Inspired by your trailer construction methods I shall look for a suitable aluminium step ladder to make a stand.

 

[DBCohen]

How much did you pay for the panels?

 

[flecc]

I have a source of lead acid batteries for incidental use. I use my car very littele, and after four to five years the batteries are no longer reliable for starting due to sulphating with low usage. However, for lighter duties, each one lasts long enough to be replaced by the next car failed one. I've been doing this for nearly twenty years now.

My main use for the old batteries has been for emergency power to run lighting, TV etc, since we had years of mains supply unreliability with several hour loss of supply at least once each winter. That seem to have been sorted now, but I've no doubt these used car batteries would do the solar intermediary job ok, given the small currents.
.

 

[Ian]

How much did you pay for the panels?

£57.50 each, see ebay item number 160121985768

 

[Flying Kiwi]

Foldable Solar charger panels

For people with megabucks (alas not me ) who want full independance from the mains whilst touring around, there's always these: PowerFilm Inc. - The worlds most lightweight and flexible solar panels and at 60 Watts in bright sunshine thats almost what the original Giant Twist charger outputs (assuming the 24 Volt option is chosen).

 

[DBCohen]

£57.50 each, see ebay item number 160121985768

Hmmm. Two panels, all of the extra equipment in the photo, cables at al. £200 in total? Then you have to manually move the panels to get the best sunlight.

I salute your ingenuity and willingness, Ian. But all of that demonstrates to me how far we have economically and functionally to go to get effective renewables working effectively in the home for even the simplest application.

 

[JohnInStockie]

I must admit I think we are in the wrong country for solar. But your would have thought that with us being a relatively wet island, that much much more investment would have gone into water and hydro

How many inlets could be dammed to catch the tidal flow, and how many rivers and streams could be utilised like this (same link as the previous post).

I always find it wierd that Hydro isnt our first choice renewable energy source.

 

[flecc]

Hydro is certainly the cheapest to take advantage of, but the scale of our water in this country is so small, streams, tiny rivers etc, often with very little head of water. My last secretary who hailed from Guyana thought our description of the Thames outside as a river was highly amusing. To her it was a stream! I'd like to see more local utilisation of these scant resources, indeed all renewables, but they would only supply a bit of our house demands.

The real problem is commerce and industry, the power they use can dwarf our household use, and for them the power must be there all the time, 24/7 in many cases.

Even with a huge effort, I can't see us getting more than 15% from renewables within a lifetime, and the costs of even that would be very high, as DBCohen remarked above about solar.
.

 

[Ian]

Hmmm. Two panels, all of the extra equipment in the photo, cables at al. £200 in total? Then you have to manually move the panels to get the best sunlight.

I salute your ingenuity and willingness, Ian. But all of that demonstrates to me how far we have economically and functionally to go to get effective renewables working effectively in the home for even the simplest application.

I agree totally, my motivation is simply to charge my bike in the tempory absence of a mains supply, but to use solar as a source of everyday energy would require a huge investment and I fear that given our climate it would be less than 100% reliable. Wind or hydro power would normally be better choices but more complicated to set up, at least solar is an off the shelf plug and play solution.

Lurking in the garage I have a 26" wheel mounted brushless hub motor with no freewheel which serves as a very effective low rpm alternator, one of my many "round to-its" is to fix aluminium "sails" to the spokes and experiment with wind power.

 

[JohnInStockie]

Hydro is certainly the cheapest to take advantage of, but the scale of our water in this country is so small, streams, tiny rivers etc, often with very little head of water. My last secretary who hailed from Guyana thought our description of the Thames outside as a river was highly amusing. To her it was a stream! I'd like to see more local utilisation of these scant resources, indeed all renewables, but they would only supply a bit of our house demands.

The real problem is commerce and industry, the power they use can dwarf our household use, and for them the power must be there all the time, 24/7 in many cases.

Even with a huge effort, I can't see us getting more than 15% from renewables within a lifetime, and the costs of even that would be very high, as DBCohen remarked above about solar.
.

Flecc - I think you misunderstand, what I am refering to is the idea of a distibuted power grid as we used to have in the days of the water mill circa 150 yrs ago. I think that if we were to have literally thousands or even 10's of thousands of these small 'portable flaoting' micro-hydro systems (i.e. if we were to spend the type of money that we would get from 1 nuclear power station) then we would have a significant supply into the grid. Additionally imagine what would happen if we were to also use tidal flow across a few hundred of the thousands of tiny inlets we have in the british isles.

I think that sort of investment in a distributed grid would constitute a significant portion of our energy requirement, and all of it 100% clean.

I have calculated that in theory (found somewhere on the web) if I was to build a little pressure wheel on my brook at the bottom of my garden, with it 3-4ft per second movement and using a 10cm x 50cm paddle, then I should be able to generate about 250W of energy, 24 hours a day. I agree, no good for the national grid, but if all 20 houses that share access to that stream had one (and yes you would lose some energy in the stream), then in thoery, that could be 20 x 250W = 5KW (is that right).

Of course thats a tiny percentage of the requirement of those houses, but hopefully it expresses my point.

John

 

[flecc]

Yes, I did understand that was your meaning John, and I support doing that, but as you've said, it's a very small proportion of what those houses use. My main concern as I expressed above is that such a huge part of the consumption is due to commerce and industry. We'll still have to generate for them on a very large scale. The government originally aimed for 10% renewables, now amended to 15%, so whatever happens we'll have to have very large scale generation, for which I'm entirely happy with nuclear.

We are going to get them, so we might as well get it right. The policy choice set in 1979 for the most sensible and safest PWR type is in the right direction, and elsewhere a nuclear station build time is about four years and economic, South Korea do it in just two years. We just have to stop meekly accepting the 14 years or so that our construction industry took for Sizewell B and make them do better for a change.
.

 

[Wisper Bikes]

Wind energy?

Hi

I am currently looking for a small wind generator to charge ebike batteries similar to the type used on yachts.

Does anyone have any experience of this?

Best regards David

 

[DBCohen]

Hi

I am currently looking for a small wind generator to charge ebike batteries similar to the type used on yachts.

Does anyone have any experience of this?

Best regards David

I did some research in to this, as I was interested in doing some renewable contribution to my own power consumption - I have an environmental bent and too many computers (with an associated guilty conscience!).

Alas, wind turbines do not provide good results in typical urban setting. Unless you have a lot of land, they need to be mounted on a roof or from a side wall - and they need a really good tall mounting.

That introduces a lot of problems with vibration, and also brings in a planning permission requirement (due to the height).

If that wasn't bad enough, the turbulence resulting from your own house, surrounding buildings and trees mean that the turbine will never receive the mean wind speeds quoted for your area, and will thus be substantially less efficient than the quoted spec. from the manufacturer.

There is also a lot of over-priced junk being sold in the Wind Turbine market. Another case of you really get what you pay for, and you need good kit AND good advice. A responsible supplier will not support a house-mounted turbine, for the reasons quoted above.

The general consensus is unless there is a radical discovery in wind turbine technology, this technology is not well suited to mass urban rollout. As such, I would not expect it to be successful for e-bike charging. The solar option demonstrated above would probably be a better bet, even with the limitations.

 

[Wisper Bikes]

Thanks!

Thank goodness I asked before spending too much time!


Back to the drawing board.

Best regards David

 

[Ian]

Hi Ian

How many 12V batteries do you need to charge a Ezee Lithium Battery using the inverter.

How long does it take to charge 1 Leisure battery through your solar panels?

Thanks

Scott

Hi Scott,

A fully charged 80Ah leisure battery will run the inverter powering my Ezee NiMh charger for about 6 hours which equates to almost (but not quite!) 2 full charges of the Ezee battery. I have been using the inverter setup on caravan holidays since last Autumn so have been able to establish the above with a degree of accuracy. I'd estimate about 1½ full charges of a lithium battery with the same setup, but actual mileage on the bike should be similar.

The solar panels are a new addition and as yet are untested in the real world, but I estimate, based on measurements, that 20 hours of clear sunshine would replenish the leisure battery after a full 3½ hour charge of the Ezee battery. Obviously more panels could be added to reduce that time, the only limit being the depth of ones pocket

Ian.