solar

[dmould66]

hi
havnt been on here for a while but last time you were all very helpfull so im hoping you can help me with my planned upgrade. with all your halp i got my 500 watt hub motored trike up and running. its been very reliable in the last year and ive put lots of miles on it.its got two 20 a/h gel batteries wired together to make 24v, ive fitted extra gears and with plenty of pedalling the range is very very good and again with peddalling hill climbs are pretty good, even with my trailer.but now i whant to go touring and cant face going without so you guessed it solar. i recon i can make a nice sun shade out of a panel (it gets pretty hot here in australia) what i need is advice on the wattage i should go for and should i wire the two panels as 24v or use one for each battery? i guese the bigger the better but price and weight go up quickly. would 120 watt be any use remember its very sunny here so should be running pretty high moste of the time though i might not be able to keep it pointing at the sun 100% of the time. i would appreciate any advice but would especialy like to hear from people who have done such a mod.
cheers
dave

 

[dogman dan]

Figure the watthours per day you need, then use a chart for your area's average insolation to get the size panels you'd need to get the battery filled.

So your battery is 12v 20 ah. 240 watthours at most. Likely you'd never pull it deeper than 200wh. So at most you need 400wh to charge both, more or less. Assuming you don't get much more than 5-6 hours of average daily insolation in your area, 100w of panel would be enough to charge both batteries. 20w panels are fairly cheap, and about the right size. Maybe start with two or more of them and see if it's enough. Add more if not. 4 panels would be fairly easy to carry, (80w total) but any more would get harder and harder to lug around.

Re the insolation, it's not so much because only at the middle of the day do you get the best angle of the sun on the panels.

 

[John in CR]

Fit as much as you can reasonably mount and can afford.

 

[nechaus]

IF i was you, i would..

Change batteries.. something lighter and something that can charge faster than your gels


+ as many watts of panels as you can afford, don't go to jaycar!!!
be cheaper to buy a panel off the net

 

[dmould66]

i could afford one of these-just
what do you think?

 

[ElectricEd]

don't go to jaycar!!!

Here here. A workmate bought 2 40 watt PV panels from Jaycar for keeping his standby 4wd battery topped up while he wasn't using it. When he checked the battery before a trip he found that it was buggered, as soon as he disconnected the panels the voltage dropped back to 8V. When trying to figure out what the problem was he took the cover off the terminal box on one of the panels. Something didn't look right. :? The discharge inhibit diode had been placed in parallel with the panel! On checking the second panel he found that it was wired the same way. Over each night for several months the panels were discharging the battery and because they weren't sufficient bring the battery back on the next day's charge they had ruined it.
He went back to the store and showed the problem and the salesman said that that is how they are supposed to be wired! Doh!
My workmate explained what the diode was for and why it was wired incorrectly. They wouldn't acknowledge that they were wired up incorrectly and flatly refused to come to the party regarding the ruined battery.
So check very carefully before buying PV panels from Jaycar.

 

[dmould66]

sorry my link didnt work-anyway what im thinking of getting is a 190 watt, 1650 x 990mm, 15kg panel designed for use on the roof of a house and im thinking of building into/onto a flat bed trailer,iknow its heavy but would it keep my batteries charged on a super long distance drive?

 

[dogman dan]

a reasonable guess would be that a 190 watt panel mounted on a trailer, tilted towards the sun all day would produce at most 1000 wh. Then you would lose quite a bit of that depending on how and what you charged with. I couldn't see traveling with much more panel than that. Bear in mind, wind resistance and weight are going to slash your normal range.


You wouldn't have a setup that would let you just ride all day continuously keeping fully charged. But it would be enough capacity to double your range I think.

But you could also triple your range by just getting a decent lithium battery. Like a ping lifepo4. The question is, would you be riding out to where there is no plugs at all?

 

[dmould66]

thanks for your help on this dogman
yes im working torwards taking my trike across the nullabor plain- about a thousand k's with not a lot in between (about three road houses and very very few dwellings (about 4) so no plugs buts lots of sun)
i hear what your saying about the lithium but i havnt got a good supply here and the price is realy scary-

have you got any suggestions as to what i could be doing to maximise my range on a tightish budget .

again thanks for your imput

 

[amberwolf]

lower weight, improve aero.

 

[dogman dan]

Yep, but harder to do aero when your panel is pointed funny to catch the sun. Riding away from the sun would be worst.

A tiny generator is easier to carry aero, but again, the damn weight.

Which leaves as a solution, pedal your ass off. Making it debateable whether lugging batteries at all is so smart. If it worked THAT good, we'd all be showing off our solar panel powered ebikes. Fact is, it's not so great.

But it could work for you, if you just deal with short distances early each day, then set up the panels and get charged. Perhaps you can get by with a lighter panel, say 80-100w. Crawling along of course, greatly extends range by lessening wind drag. Another reason to ride early, when there is the least wind, unless afternoon sees you with tailwinds.

 

[nechaus]

if your in brisbane, i can sell you some Thundersky 24 volt 40 ah battery pack. Safe Lithium chemistry (lifepo4)

 

[dmould66]

if your in brisbane, i can sell you some Thundersky 24 volt 40 ah battery pack. Safe Lithium chemistry (lifepo4)

im in dubbo- western nsw - but thanks for the offer.

been whatching the sun alot recently and it gets overhead pretty quickly and is there for the bulk of the day- i can see how normal riding conditions can make pointing the panel at the sun a big problem but im going to be riding in a pretty constant direction day in day out, in an area where shade can be a problem, and the sun shines alot - so i think i will be able to maintain a reasonable charge- obviously if i need to stop and let the sun do its work i will have to make camp.

i understand completely why people are advising me to go high tec batts but these are outside my understanding and ive found that if you dont understand something you pay top dollar-something i cant afford to do. so im going to stick with sla.

where im up to to date, im going to get a full size "house" panel and mount it as low as i can on the lightest two wheeled trailer i can lash together, hopefully in a way that allows as much positioning as possible- then do as many tests as i can- if it helps ill take it if it dosnt ill put it on my house.
what im not sure about yet is, as my system is 24 volt i intend buying a 24volt panel, do i wire it to my two batteries as if they are one, or do i need two 12volt panels, if so do two, say 50 watt panels make a 100 watt? i suspect not.

any ozzies ever tried the nullabor with solar? i see lots of americans in the desert where the conditions look similar. the burning man sites often show trikes etc with panels, are all these people mad or do they fail and just drift sillently away? come whos done a long range desert tour on a solar only charged bike and lived to tell the tail, obviosly if you perished you whont be able to help me but i salute your spirit anyway!

 

[ddk]

if I were to do something similar to what you're attempting
I would mount the panel(s)above me (instant shade- ya baby!
and assuming I'd stay with a 24v battery i'd use 24 volt panel(s) hooked directly to the battery- no charge controller needed
200w of panel would be sufficient at the speeds I like to travel- although carrying water (weight is like, heavy) might suggest I should up the panels to 250w
but I'm like interested in poking along at 10mph or less

 

[dmould66]

if I were to do something similar to what you're attempting
I would mount the panel(s)above me (instant shade- ya baby!
and assuming I'd stay with a 24v battery i'd use 24 volt panel(s) hooked directly to the battery- no charge controller needed
200w of panel would be sufficient at the speeds I like to travel- although carrying water (weight is like, heavy) might suggest I should up the panels to 250w
but I'm like interested in poking along at 10mph or less

im pretty slow as well, realy not worried about speed if i was i would buy a big car and knock it out in a couple of days,

i thought about the shade thing but im worried the wind blast from the road trains might cause me to take off- does make sense though

is two 12 volt batteries wired up to make 24v equivalent to one batterie-ie i only need one panel?

 

[ddk]

iblah blah blah

im pretty slow as well, realy not worried about speed if i was i would buy a big car and knock it out in a couple of days,

i thought about the shade thing but im worried the wind blast from the road trains might cause me to take off- does make sense though

is two 12 volt batteries wired up to make 24v equivalent to one batterie-ie i only need one panel?

ya
I think of battery banks as 'one' battery
for instance I use a 200w 12v solar array (15.4v nominal) charging 4 banks of batteries, auto switched when each bank is fully charges. However I do use a MPPT charge controller because there are days I don't use much power from the batteries and not only does it completely "top off" each bank (takes forever-lol) but it also keeps the batteries safe from overcharging.
If I knew I would be consistently drawing a healthy amount of current from my banks I wouldn't bother with the MPPT charge controller, as the batteries would never approach a 100% charge.
Might be different (no-WOULD be different) if I used a different battery chemistry other than lead acid.

3 of the banks are 2 each 6volt deep-cycle watered lead acid batteries hooked in series and one bank is 8- 12v AGM batteries hooked in parallel (Thanks Rassy!)
but I only think of each bank as a 'battery'

 

[dmould66]

thanks
how long would you expect a 200 watt panel to charge a 20 a/h battery from flat to full?

 

[ddk]

I just remembered something you might not like
12-20 amp/hour batteries only bulk charge @ around 2amps per hour
so if your battery is fully discharged... lol-never fully discharge your battery or you just killed it permanently.
charging it from 50% to 100% would take 10+ hours (2-3 days)
HOWEVER
If your 'moving on' the motor is pulling power from both the battery and solar panels, becoming a useful system while the sun is shining
assuming 100% of those 200 watts (never happens) the solar panel would be providing the bulk of the current to the motor but this is dependent upon your particular motor/controller efficiency any 'leftover' current is effectively charging your battery which, just sitting there are happily discharging at a 3% rate per day (lead acid sux but it's cheap)

I regularly average 10 amps out of my panels for 4-5 hours on sunny days or around 120w instead of it's (poorly) rated 200w

@ 10000 feet above sea level in July I saw 24 amps from my panels (blew my homebrew MPPT controller because I'd failed to properly solder in some of the fets HAHAHAHAHAHA-it sucks to be old)

 

[dmould66]

I just remembered something you might not like
12-20 amp/hour batteries only bulk charge @ around 2amps per hour
so if your battery is fully discharged... lol-never fully discharge your battery or you just killed it permanently.
charging it from 50% to 100% would take 10+ hours (2-3 days)
HOWEVER
If your 'moving on' the motor is pulling power from both the battery and solar panels, becoming a useful system while the sun is shining
assuming 100% of those 200 watts (never happens) the solar panel would be providing the bulk of the current to the motor but this is dependent upon your particular motor/controller efficiency any 'leftover' current is effectively charging your battery which, just sitting there are happily discharging at a 3% rate per day (lead acid sux but it's cheap)

I regularly average 10 amps out of my panels for 4-5 hours on sunny days or around 120w instead of it's (poorly) rated 200w

@ 10000 feet above sea level in July I saw 24 amps from my panels (blew my homebrew MPPT controller because I'd failed to properly solder in some of the fets HAHAHAHAHAHA-it sucks to be old)

the bit about drawing current from the panels sounds brilliant, all the ngative stuff ive red on the web was starting to make that sound impossible and i was consentrating on using them to charge.

so it just a possitive and negative wire to the battery terminals, no charge controller and off you go?
where do you do your riding?

 

[dmould66]

also just thought if my battery is discharging at 3% a day it would last quite awhile before it became useless right?

 

[ddk]

LOL
'murica

BTW my panels are mounted on my 'house', not my trike
I live in a motorhome which is how my panels have gone to very high places and very low places.

much of what I've read on the web about solar panels coming from 'experts' is absolutely right
except... they aren't making the connection that one might want to use that solar energy for directly powering a vehicle, with perhaps some of the energy charging batteries.
I think of the batteries in a solar electric system as being a 'resevoir' and a voltage regulator because I thinks all wrong

and the biggest thing is, on this forum al least, everyone wants to travel @ 30mph (I forget the kph atm)
which requires FAR FAR more energy then traveling @ say, 8-10mph

and yep- takes about a month or more for the battery to get in the danger zone but I gets all twitchy after three weeks of no sun and will either fire up my generator or 'plug in'

 

[dmould66]

LOL
'murica

BTW my panels are mounted on my 'house', not my trike
I live in a motorhome which is how my panels have gone to very high places and very low places.

much of what I've read on the web about solar panels coming from 'experts' is absolutely right
except... they aren't making the connection that one might want to use that solar energy for directly powering a vehicle, with perhaps some of the energy charging batteries.
I think of the batteries in a solar electric system as being a 'resevoir' and a voltage regulator because I thinks all wrong

and the biggest thing is, on this forum al least, everyone wants to travel @ 30mph (I forget the kph atm)
which requires FAR FAR more energy then traveling @ say, 8-10mph

and yep- takes about a month or more for the battery to get in the danger zone but I gets all twitchy after three weeks of no
sun and will either fire up my generator or 'plug in'

cool i lived mobile for many many years-miss it bad!

good to hear someone say it can be done- i admit im not knowledgeable when it comes to solar but alot of people here have panels on there roof and run entire houses of them-i look at my little hub motor and think why not? suns bloody bright here! after hearing what youve had to say im going to order a panel and see how it goes- i will let you know how it peforms many thanks

 

[LegendLength]

If you want to use solar you really need to become a weight weenie. IMO there's no other way than to strip down every gram of unwanted material. The amount of power you get from a 15 kg (30 lbs) panel in a trailer, plus the weight of the trailer, plus the drag would possibly be negative.

I also live in NSW and ordering Lipo / LiFe batteries is cheap and easy. It takes a few weeks but that's the price you pay for good value (and chinese labour).

Your best bet is purchasing the thinnest, lightest solar panels you can find within your budget. Get 5 or 10 kg (10 to 20 lbs) of Lipo and build a solid, puncture-proof box for it. Get a small motorcycle battery and use that as a 'cache' for the energy coming in from the solar panel. Recharge your lipos using the lead acid battery. I'd even go for a very lightweight motor such as the cute 100 if speed doesn't concern you.

If you still want to go the heavy route, at least do some napkin calculations to see roughly how much power you will gain.

 

[dmould66]

I also live in NSW and ordering Lipo / LiFe batteries is cheap and easy. It takes a few weeks but that's the price you pay for good value (and chinese labour).

so where do you get your batts? easy yes- cheap? my sla's were $60 each delivered

 

[ddk]

the problem with thin cell and flexible solar panels continues to be their efficiency.

The trade off is twice the physical size of a flex panel vs. twice the weight for a mono or ploy 'classic' panel.
And there's the (unanswered) question of long-term reliability of the thin panels.

Some napkin calculations of what I'm dealing with is a 'standard' 200-250 watt panel of mono or polycrystalline construction
weighs in at around 40-45Lbs (around 19kg)
I don't consider that weight to be much of a negative... if I didn't have to carry 10kg of tools to keep my POS trike on the road

A 'standard' house panel of 200-240 watts size averages ~ 40" (~900mm) x 62" (~1600mm)
All the thin panel/flex panels I've seen on the market would be twice that size, but as always, I hasn't seen everything.

Where I ride a 'standard' 240 watt panel is about 10" too wide for my comfort zone (the width of some local bicycle lanes narrows to less than 48" and we all know how close some drivers get to the bike lanes... so I'm not bothering to power my trike in this manner

and I've no intention to travel more then 10 miles from 'where I lives'

a side note- my trike DOES have a Cute100 motor.
With no pedaling assistance from me the trike speeds along at 8mph using an average of 75 watts per hour