eBike Touring

[BBassett]

I own a SunCapture 300W folding solar panel and would like to be able to use it to heat water for washing. I would like to be able to heat water and fill an Helio pressurized shower on tour. (https://www.youtube.com/watch?v=DBmafwdPzes) There are all kinds of 12V/24V car immersion heating elements, even DC water heater elements that I could use. Is it as simple as connecting the panel to a heater through an adjustable dc/dc converter and dialing the appropriate voltage? Thanks for any help.

[bob-n]

There are many ways to do this. Some are more efficient than others.

Unfortunately, that solar panel is less than 20% efficient, meaning that it wastes 80% of the sunlight coming on it. The dc/dc converter will waste a bit more. On the positive side, an immersion heater is 100% efficient.

The most effective way to get energy out of a panel is with a maximum power point tracking (MPPT) converter that adjusts its conversion ratio to get as much power as possible out of the panel. A simple DC/DC converter (often called PWM) will also work, but not as efficiently. Both are PWM, but people save that term for the simpler system.

The most efficient solution (60%+ efficient) is to direct the sunlight at a black water collector and let it heat the water directly.

[BBassett]

Unfortunately, that solar panel is less than 20% efficient... I think the SunCapture is more like 23.8% or some such but it really doesn't matter as I already have and use it and it's folding. I use it to charge the 30Ah lithium packs for the bike and a few 12V items like a Fugoo XL speaker. - https://photos.app.goo.gl/rFim5rPsajmDt8NJ6

The most effective way to get energy out of a panel is with a maximum power point tracking (MPPT) converter... Yeah, got one set to 56.8V for the lithium packs plus a Grin adjustable dc/dc converter. I just want to know if it is easily done with what I have and don't care if it's the latest and greatest.

Note: I was wrong...

"HPC SunCapture 300. A 300W portable and foldable solar panel that will power your most prized possesions directly from the Sun! These panels are made with the world's highest efficiency Sunpower Maxeon Gen 3 solar cells purchased here in the United States and provide an energy conversion rate of a whopping 24.2%! These panels are meticulously hand-sewn into heavy-duty waterproof Nylon for a robust yet lightweight folding design."

I would like to argue the use of the word "lightweight" and have to point out that none of my "prized possessions" needs electricity.

Stay safe.

[bob-n]

Yes, that is surprisingly efficient. Sorry for my error.

Back to your question - yes, you can simply follow your MPPT converter with a DC/DC down converter. I'm not sure what the Grin is, but if it accepts 56.8V and puts out 12V or 24V, you may be all set. Just make sure that the current level is compatible. In other words, make sure that your heater is 200 watts or less and that your DC/DC converter can put out the current required. I suggest a 200 watt limit because you won't always have full sun.

[BBassett]

Yes, that is surprisingly efficient. Sorry for my error.

Back to your question - yes, you can simply follow your MPPT converter with a DC/DC down converter. I'm not sure what the Grin is, but if it accepts 56.8V and puts out 12V or 24V, you may be all set. Just make sure that the current level is compatible. In other words, make sure that your heater is 200 watts or less and that your DC/DC converter can put out the current required. I suggest a 200 watt limit because you won't always have full sun.

But I can run it off the ebike lithium pack even at night right? https://www.ebikes.ca/shop/electric-...rs/dc-adj.html

[bob-n]

Yes, you can use the lithium battery into the DC/DC to make 12V for a heater, or anything else that needs 12V DC, as long as it is within the current and power rating of the converter and battery..

The link you showed is for an adjustable DC/DC converter. It mentions a potentiometer to adjust output voltage. That probably means that you need a voltmeter to set the output voltage. If you plan to change output voltage on the road, you may need to carry the meter with you.

[BBassett]

Yes, you can use the lithium battery into the DC/DC to make 12V for a heater, or anything else that needs 12V DC, as long as it is within the current and power rating of the converter and battery..

The link you showed is for an adjustable DC/DC converter. It mentions a potentiometer to adjust output voltage. That probably means that you need a voltmeter to set the output voltage. If you plan to change output voltage on the road, you may need to carry the meter with you.

Thanks... I always do. Stay safe.

[Mike90250]

You are going to be much better off getting a SolarShower bag and use that for heating water. Or a small propane fired water heater to run off a 16 oz tank.

You need to mount the PV panel in the sun for charging the battery to run the heater. Trying to get a MPPT DC-DC converter is a toughie, easier and more reliable to have a battery and use a DC water heater element. then you need a metal tank for the water, so the element does not melt plastic.

https://www.amazon.com/camping-water-heater-propane/s?k=camping+water+heater+propane

good luck

[BBassett]

You are going to be much better off getting a SolarShower bag and use that for heating water. Or a small propane fired water heater to run off a 16 oz tank.

You need to mount the PV panel in the sun for charging the battery to run the heater. Trying to get a MPPT DC-DC converter is a toughie, easier and more reliable to have a battery and use a DC water heater element. then you need a metal tank for the water, so the element does not melt plastic.

https://www.amazon.com/camping-water-heater-propane/s?k=camping+water+heater+propane

good luck

I have a black solar shower bag that I use connected to a ShowerCoil (http://www.boundarytec.com/1530-show...ing-shower.php) with wood fires, also a mini-mo propane stove with a copper coil. I just wanted another option. I am going to make a 12V dc immersion heater with a dc water heater element that can be powered with either the panel or a pack. My panel is 10 SunPower cells in folding nylon. It's small and reasonably light for travel and still 300W when in use... or 150W if folded in half. The convenience of having a foldable panel is countered by additional weight, 17 pounds, but worth every ounce. Once I could charge the lithium packs with solar I needed to be able to charge all the other 120V items and the Grin Adjustable dc/dc converter has let me do that using the panel or batteries. The easy way to go would be to get a car immersion heater and drop in into a double wall stainless steel bottle and feed it 12V. I want to be able to heat enough water to wash my hair and shower, even wash the bike and gear. It may take connecting a thermostat to the water heater element so it won't boil water. Screw it into a 2" CPVC tube with holes drilled over the entire length and drop it into water. Just like a home or restaurant wand immersion heater. Dial it in right and maybe I can sous vide fresh-caught trout this summer.