Using a 100 Watt Solar Panel to Heat One Gallon of Water 

Good plan! On another vid a guy used some nichrome wire and a PV panel to heat a tin of sand. The box of sand stayed at around 200C to 300C. He used it for his everyday cooking, which seemed to be a very simple concept.

Great insight on the basics and a simple set up, thank you! I would suggest adding protection for the panel. Keep sharing :))

smart man excellent effort and thanks

Use the electricity captured via solar panels to drive the heat pump on a water heater equipped with such. They have a very high coefficient of performance (CoP) so they capture 3 to 4 units of heat for every unit of electricity used. They are more expensive, but the ROI is typically 18 to 24 months, on a unit made to last 10 to 12 years. If you have a few hundred extra dollars, they will save you thousands over the long run.

It is amazing the flat current line you can get with continuously tracking the sun. It does give those who will have fixed panels a false sense of performance. Especially with direct connect which is a poor performer. One study indicated the ideal resistance could be doubled and more overall daily output obtained. This is due to the fact that most of the day current will be much less than Imp. The solar world still is in the dark ages when it comes to heating water. Controllers which electronically match the panel to the heating element are still quite expensive and not designed to last as long as the tank. For those inclined to build their own, these controls are fairly simple and cheap to build. I made one out of a $10 inverter board. Higher voltage with grid tie panels is the way to go. For $500 you can have PV hot water system.

From Pakistan ...great thanks

I was thinking that this same principle could be used to keep drinking water from freezing at a camp or off-grid 2nd home in between visits. Loosely extrapolating from your data, it's conceivable that even a single 100W panel with a similar 12V heater could serve this function (with a well insulated tank) depending on one's latitude. Thank you for sharing this info!

I use solar panel to cook. It works. It saves energy I can prepare and forget, tasty and healthy. I incredibly hate cooking 😂. Solar panel + Topf is ideal. Need dog to give him bones and clean plates😂😂😂😊

Nice experiment! However, I think you missed one thing. At least one can’t tell for sure if you missed it or not. You resultant number of panels seems a bit high to me based on some other rougher calculations I’ve done for a similar contemplate project. The issue I believe is that you only used one panel which almost invariably is not impedance matched to the resistance of your element. A key result in electrical engineering is the maximum power transfer between a source and a sink can only happen when the impedance (here just resistance) of both are the same. A single solar panel has a resistance of about 3 ohms. Most water heaters have a resistance between about 9 to 12 ohms (which does shift due to temperature). This means that your resistance is mismatched, and you will not get maximum power transfer from the solar panel. A 2 to 1 mismatch will result in about 10% loss of power. You are running closer to three to one, maybe 4 to 1. This could notch you down to many about a 30% loss of power. This means that your projected 14 panel requirement should really be between 9-12 achieved by wiring them up in combinations of series and parallel groups such that the combination provides the same internal resistance as your heating element. Is your heating element is 9 ohms, then three panels in series would get you 9 ohms of panel resistance. Double that to 6 panels in series to get 18 ohms. Then put an identical string of 6 series connected panels in parallel with the first series string and that gets you back down to 9 ohms, and almost perfect match to the 9 ohms heater resistance for near 100% power transfer. And you saved a couple hundred bucks in the process. There are of course other ways to wire it. And the heater resistance might be different than this example. Key is that the resistances match as closely as possible.

Good experimenting. I have an engineering background and love the garage tinkering and have done similar experiments. Recording data and spreadsheets is good practice so I am one of the few that won't get bored looking at that stuff. ha! I have several DC immersion heating elements but have only had time to test a few. Did you mention the sepcs on your heat element?

I know a really realy cheap way to do it. Get a panel heater and inside is a very thin wire with a silicone coating, and if you put this wire on a 12 volt supply you get infrared heating, and I put the wire all over my mattress and its amazing, but if you stick this wire inside something lime a beer keg it will heat water and keep it hot. (Never tried but the wire is from 2000w heater)

Use the solar power to drive a pump that circulates the water inside of a safe pipe inside of a wood frame with a plastic surface towards the sun. Much more efficient use of solar power.

Just one briquette of charcoal and 10 drops of lighter fluid out performes this a thousand times over in every way.

Very informative video thanks for taking the time to show the world. I have a question I'm thinking to add in my scholie motorhome conversion a 6gln water tank with 100W solar panel can you help with what size in watts 12V element should I pair with. Will the water stay hot/warm overnight installation would be inside and the home is well insulated. Your help is highly appreciated.

You covered part of the panel with the wood...

This is all good but those DC Elements dont go directly onto my standard hot water tank There a screw on Element ...The original element is AC 240 VOLT 2000 WATTS is a 4 bolts to a 70mm square plate . So how are you going to fit that DC Element to your standard water tank everyone got Because thats what your ultimately wanting to do . ???

how about using 24 watt panels? and two 400 watt panels will be enough to heat up the water

What was the voltage on elliment?

Can't say that moving a panel all day is really a fair test. All studies have shown a normal bell curve where power drops off rapidly beyond the normal 2hr mid day period. A 12V heating element is never a good match for a 12V panel, did you put those elements in series? These sunny day videos give people unrealistic expectations of what can be achieved. Power is a function of the square of the current. I design power point water heater controllers and when the current drops to 20% of a panels rating, you need five times more panels than when a power point controller is used. Wasting capacity of a power bank and over sizing equipment is not the way to heat water. I heat three water tanks with the same panel power that goes to the charge controller. That power would otherwise be wasted and more than half my panels are shaded at any one time.

Yeah, shading a third of the module surface which are connected in series is probably not the best idea.

Let me get this straight. You're using a heat source (sunlight) to make electricity to make heat? Huh?