Solar panel to DC heating element to pre-heat water before on demand water heater

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22 Days On DC Hot Water Heater (Update) Living Off The Grid, So things are looking good its now been 22 days I have been using my DC Hot Water Heater and I am super happy. I still need to do a couple of things to make it even more better. I am not using propane.

Welcome to my channel: My channel is about How I use renewable energy to live off the Grid on the Big Island of Hawaii. I use renewable energy Wind Turbines Solar Panels and other ways to achieve my way of life. I started my channel because I wanted to share my experience living the off grid. I started with a small 12v off gird system and now I am building a Brand New 48v Off Grid Home here in Hawaii. If you follow me you will see where i started and where i am going. I am sharing the way i have done this and want to share any tips i can to help others that may be in the same situation or may be thinking about living off the grid. There is a lot of good information on my channel and a lot more to come. My...

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Only electric hot water heaters use heating elements to warm the water inside the tank and provide hot water to the home. Gas-fired models have a burner at the base of the heater that warms water inside the tank. Heating elements typically last for several years, and hot water tanks outlast the elements. You need not replace heating elements periodically, only when symptoms arise.

Symptoms of a Bad Element

A sudden lack of sufficient hot water is often a warning that a heating element has burned out. Most electric water tanks have two elements. The lower one typically burns out before and more frequently than the top element simply because of sediment in the water supply and the element’s location on the tank. Another symptom of a bad element is a tank that takes longer to recharge with heated water than it had previously. Before considering replacing the elements, check the reset button located near the upper element. Press to reset it, which might fix the problem....

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I think you will need on the order of a 10kW to make a demand heater. I dealt with this in a when putting a demand heater in my hangar shower. I ended up using gas because of the huge electrical demand.

Read this:
Your Home’s Electric Service
May Need to be Upgraded
Tankless electric water heaters usually require
an upgrade in electrical service, something
the home improvement stores often do not
mention.
A tank water heater with 4,500-watt elements
operates on #10 wire and a 30-amp circuit
breaker. One whole-house tankless water
heater has four 7,000-watt elements, for a total
electrical load of 28,000 watts. This load requires
wire and a circuit breaker that will handle
at least 120 amps, at a cost many times that of
electrical service to a conventional tank water

It came from this pdf

Redo the power requirements using these...

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Heat your water for free with a solar water heater. This $300 DIY solar water heater system even includes an electric backup water heater for cloudy days. It heats water to 135F (55C) on sunny days in a 80 gallon (310 liter) tank - and there are no moving parts - it relies in a thermosyphon to circulate the water.

http://www.myfixlog.com/fix.php?fid=1
This heater uses PVC instead of copper. PVC has a much lower thermal conductivity than PVC does, however there are a few ways to over come this weakness.

One way to I increased the efficiency was to use old florescent light bulbs as sleeves over the PVC pipe to act as a double glazing. This helps insulate the PVC and increases the efficiency of the heater. I also insulated the PVC connections to help shield them from the intense heat of sunlight.

The other way I increased efficient was increasing the surface area. Since PVC is cheap it did not cost much to run more pipes that would be exposed to the...

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In addition to the good advice above, here is an old time GRAPHICAL solution to performance of

a PV panel source connected to a resistance heater load. With a 0.3 ohm heater 3V gives 10A

of current, 6V gives 20A, and so on. Plotting these point gives a straight load line from 0,0.

Then plot the power curve of a 12Vmp 20Amp 240W panel. 15Voc, 25Asc. These 3 points give
a rough curve as shown. That gives a max power point at A, 12V X 20A = 240W.

However, conditions hardly ever give the ideal maximum, so lets plot a more achievable PV curve
at 80%, or 192W. Vmp will hardly vary at 12V, Imp drops to 16A. At B power is 192W. The
heater load line intersects at C 5.8V, 19.5A, this is where they would operate if connected
together. But only 113W, or 59% of the available power is delivered.

100% efficiency could be achieved if the load line ran right through the panel MP point B. 12V
divided by 16A (ohms law) gives a...

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Types of Solar Water Heating Systems

Pre Heat Solar Tank System:

This type of solar water heating uses two tanks The 1st tank is called a solar pre heat tank and is a basic solar hot water storage tank. The solar pre-heat tank is used to supplement warm water to an existing hot water tank. This type of solar water heating is the most common retrofit as it uses the existing hot water tank and needs very little retrofit to the plumbing. The existing main supply line is routed to the pre-heat tank and then drawn back into the supply line after it is heated.

The most efficient solar hot water heaters use the basic theory of stratification. In stratification the solar hot water theater is heated using thermosiphon (or a very slow pump). This slow mixing of the water means the top layers are always the hottest. As the top water is drawn into the main tank, the hottest water is always used 1st. Since the average house hold used hot water in batches (not...

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Now go build one. It's not going to build itself! You can preheat water for any type of water heating system, gas or electric, tankless or with a tank, and it will translate into savings for you. Just be safe and get professional help if you have to in order to follow local codes and so forth. Yes, that was a disclaimer.

Remember, even if what you build is not enough to supply all your needs, that doesn't matter. If it just supplements what you have, then every bit of energy you harvest is money saved! It amounts to turning sunlight into money!

Oh, one other thing --- If the ambient outdoor temperature is higher than the temperature of the water coming out of your supply pipe, this thing will work even without sunlight. That's right... on a cloudy day or even at night! If your water comes out of the supply pipe at 55 degrees and it is a cloudy, but warm 80 degree day (or night), the water will still circulate until the holding tank is at 80 degrees. And...

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Re: I want to run my water heater on solar power (Newbie)

Calculating the size panel/heat required... I have not done the calculations before, so below is a guess/estimate. But because solar thermal panels are not as expensive, you can oversize a bit without too much extra costs.

Say, 40 gallons of water per day, raise temperature from 40F to 130F:

130F-40F = 90F rise 90F rise * 8 lbs per gallon * 40 gallons per day = 28,800 BTU per day 28,800 BTU per day / 3.4 BTU per Watt*Hour = 8,470 WH per day

So, the standard solar PV + Battery estimate would be... 4 hours of sun minimum (9 months of year typical for many regions in North America), 0.52 end to end system efficiency for off grid system, battery for 1-3 days and 50% maximum discharge (longer life). Nominal calculation:

8,470 WH per day * 1/0.52 system eff * 1/4 hours of sun per day = 4,072 watt array minimum 8,470 WH per day * 1/48 volt battery bank * 1/0.85 inverter eff * 2 days no sun * 1/0.50 max...
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This is a Solar hot water Batch Type pre-heater that pre-heats the water for my hot water tank inside the house. Cost $45.00 to build. I made it out of garage sale and Goodwill items and scrap wood I had laying around. It has been heating water up to 140 degrees and circulates thru the tank by natural flow no pump needed as it is lower than the main tank.

This is what it looked like when I finished. I added extra insulation and foamed all the cracks.

This is a fresh water tank from an old camper trailer that was given to me. This project can be scaled up or down to suit your needs.

A piece of old peg board, A sheet of masonite would have worked better but this is what I had.

Cut frames and sides from scrap plywood. This is not the true curve but it is what I had for material.

3 pieces of .50 cent glass. Foil backed styrofoam board ends scrap from a garage remodel.

Tank painted .96 cent Wall Mart black. 99 cent space blanket glued to the peg...

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More Info on Solar Panels

What are solar panels?

The term solar panels is often used for a few different types of products that produce energy by collecting sunlight. We most commonly use the phrase to refer to the type that converts sunlight directly into DC electricity. Less frequently, people will use the term in reference to solar thermal collectors, which typically heats a liquid such as water, or solar air heaters, which heats air directly.

How does a solar panel work?


Quick Version

Rays of sunlight hit solar cells, pushing the electrons in the cell through the wires to create electricity. This electricity is in one direction, so it is called DC, for Direct Current. As opposed to AC, for Alternating Current, where the electrons are going back and forth 50-60 times (50-60Hz) per second. That is why for most installations, you need an inverter. An inverter changes the DC to AC and makes it usable with your home's appliances.

Detailed...
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