MPPT DC Solar Hot Water

Solar Hot Water – The Easy Way!


No Pumps – No Pipes – No Plumbing – Simple Hot Water

  • Affordable – Compare with fluid systems costing $5,000 or more!

  • Save Money – Reduced grid power usage saves you hundreds every year!

  • Maintenance Free – NO pumps, NO pipes, NO freezing to worry about!

  • Less Equipment – NO batteries, NO inverters, NO charge controllers!

  • Always Hot – Hybrid hot water on bad solar days / solar if grid is down!

  • Grid Power Backup – Dark cloudy days are not a problem!

  • Winter Cold Proof – Solar PV panels work when fluid systems would be too cold

  • Freeze Proof – No outside pipes to freeze, solves problems fluid systems have

  • MPPT – Microprocessor controlled constant Maximum Power Point Tracking

  • Light Cloudy Days – MPPT technology keeps the heat coming!

  • No Batteries – Batteries are a pain! Lots of energy loss, messy, 5 yr lifespan

  • Upgradeable System – Add more solar panels or a second unit as you go

  • Time Of Use Ready – Got high PEAK POWER PRICES? This will help!

  • Eco Friendly – Reduced CO2 emissions! Reduce your carbon footprint!

  • Home Value – You own the solar panels, not the power company!

  • Easy Install SHW – Two wires in and two wires out!

  • Uses Installed Heater – Uses the existing electric water heater in most cases

  • No Element Change – No heating element change is needed in most cases

  • No Thermostat Change – No thermostat change is needed in most cases

  • Off Grid Possible – Completely off grid is possible, see our other systems!

  • Off Grid Already? No Battery Drain – Less or no draw from your battery system

  • “Smart” Meter Ready – No power company contracts or hassles!

  • UL 1741 Compliant – UL, NEC and NEMA compliant, see Specs below

  • Made in the USA – Designed and manufactured in the USA


Why RENT your power when you can EASILY OWN IT?

What this will do for you:

You are already paying to heat water in your home, this innovative product, the Solar Hybrid Hot Water Controller will save money on your power bill by supplementing your hot water heater power usage with free solar power.

  • FREE ENERGY FROM THE SUN heats your water with a low cost, simple, easy to install system.

  • No pumps, pipes, re-plumbing, leaks or freezing to worry about, just two simple wires! No need to drain the tank.

  • Wires are a lot easier to run than doing plumbing with solar hot water.

  • Only minor modifications are needed for most standard water heaters, simple wiring modifications. NO HEATING ELEMENT CHANGES NEEDED. The wiring modifications are easily reversible.

  • You can Do It Yourself DIY or ask your local professional solar installer or dealer from our growing list about how well it works!

See it in operation! See video below!


See the TechLuck-SHWC-1 in operation in this VIDEO

Tolnix Report

Product: TeckLuck MPPT DC Solar Hot Water Controller

Brief: My 400lt stainless steel tank with thermal solar needed a boost – and I needed some daytime heating with my LVI oil heaters, but didn’t want to pay!

I can’t fault the product, but the hype surrounding the advertising is a little ridiculous. I guess with it’s high price, there has to be a lot of “selling”?

The electrical engineer behind the product is pretty one-eyed about his invention, though I must say – it is a very simple, yet well thought out design with all the work being done by the PIC programing. This takes time, knowledge and understanding so the theory behind it is brilliant to say the least.

One thing to note is his insistence on housing it a certain way – I chose to strip down an old solar inverter and mount it inside directly to the massive heat sink. If you are running the maximum solar through, I highly recommend this and even adding a cooling fan to preserve the electronics – it gets HOT!

A very good point being it will equal a flat panel thermal collectors temperature – though in lower volumes. Is easier than having to expand or install solar thermal hot water panels that are virtually obsolete. Some evacuated tube systems still fair well warming larger volumes of water.

This unit is great for electric water heating elements and electric oil heaters to provide FREE heating while the sun shines! Good after sales service – but you do pay a premium for a quality product. Between 30-50% above it’s nearest competitor.

The only downsides – the high cost for what seems to be well under $100 in parts, requires specific resistance (watts/voltage) heating elements to work.

The upsides – it starts to work with just a hint of sun light, and continues through till dusk squeezing every bit possible from the sun!

DISCLOSURE: I have no association with this company – I have purchased 1 of these units. 6 run oil heaters, one runs a lower hot water tank element.

Your hot water tank becomes a “solar storage battery”, storing energy as heat, reducing your power bill without expensive deep cycle batteries, charge controllers or inverters.

Daily solar panel watts = watts off your bill. Maintenance free, no messy batteries to change out every 5 years, no battery charging power losses, no inverter conversion losses.

Heat conduction via MPPT solar power is by far, the most efficient method of using PV panels to heat water. The maximum power/BTUh from each solar watt-hour is efficiently converted to heat and saved as BTUh energy in your hot water tank, reducing your power bill.

The solar energy gets stored in your hot water tank and adds up all day long, simple example, about 750W all of hour 1 + 750W all of hour 2, etc.. So the upper grid backup heating element comes on less.

750W X 9 hours sun = 6,750 Wh or about 6.7 KWh a day off your bill, not bad, that’s over 200 KWh a month! Time your use and conserve and you are in pretty good shape for what you spent on this low cost system. (your daily solar output may vary)

You can have hot water when grid power is out (limited to solar wattage of course). You get hot water in the winter when fluid based systems would get too cold to work well.

Things have changed, Solar Panels are now available on a regular basis for close to 70 cents a Watt or less shipped to your door, making this the low cost choice for solar water heating! (solar panels not included)

The Solar Hybrid Hot Water Controller allows you to use a standard domestic Hot Water Heater with standard “24V” Solar Panels starting with a “48V” configuration ( 2 x “24V” ). You do not have to change the heating element in most situations!

Works equally well with “12V” panels. Many different configurations of “12V” panels are possible, starting at “48V” (4 X 12V panels) minimum.

Solar tax credits and power company rebates may be available!

No piping nightmare!

You don’t have to change the existing heating element, make any plumbing modifications, or drain the tank.

No 2nd tank. No Pumps. No chance of leaks from this mod. Piped systems cost thousands of dollars.

No battery. No charge controller. No inverter.

Save money on your power bill without messy batteries, expensive charge controllers or inverters. You can pay for all that and still have the hassles of the battery running down, running extension cords all over the house, tying into your electrical box circuits, switch over relays, UPSs and more. Batteries can have up to 50% energy loss.

With an inverter you have to balance a your AC loads with your batteries and daily solar panel output wattage, and what about cloudy days? It’s not fun adjusting your system all the time to changing conditions. Cheap, inexpensive power becomes a inverter and battery baby sitting job. This cost effective system requires little or no attention.

With the Solar Hybrid Hot Water Controller, if you put 750Wh of heat energy into your tank (SHW), you save about 750Wh every hour off your grid power use with less hassle and loss than a battery system.

Meter readings, amps and volts VIDEO

Simple to wire

Only two wires (+/-) coming from the Solar Panels and two going to the water heater are needed.

The Solar Hybrid Hot Water Controller has a CPU specially programmed for Maximum Power Point Tracking (MPPT) and continually adjusts during the day to get the most power from the Solar Panels. MPPT is especially needed in the mornings, afternoons or cloudy days to keep the most power pumping into the heating element at all times.

You can try hooking up your solar panels direct, but without MPPT you will get little heat for your investment and have other problems. See the FAQ page for more on this.

See the abuse ANY contacts would take without our special MPPT in these short videos with only TWO PV panels and notice when the wires stick together, they get welded together and copper is also being eaten away – VIDEO:

Is DC voltage hazardous?

For DC voltages, currents above 25 mA at 50 V are considered hazardous under normal conditions. For common AC outlets (60 Hz, 120 V), current above 10 mA is considered hazardous under normal conditions.

What are the safety precautions for DC power supply?

Avoid loose or frayed wires, cables, and connections. Know how to turn off all equipment, power supplies, and circuit breakers. Make sure that at least two people work on an experiment that has accessible DC power greater than 50 volts. Use the same precautions with single-phase or three-phase AC mains power.

Many different configurations are possible, such as solar plus grid power backup (hybrid) or off grid (with conservation, see our other larger systems). The nice thing about PV Electric is you could re-configure the panel wiring in an emergency as a power back-up if needed. (see the Story below)

You are always fighting daily tank heat loss. As an example, a small low wattage solar panel system of only 250W can keep a 40 gallon domestic Hot Water Heater up to temperature without any daily grid power needed (note: little or no use).

The Solar Hybrid Hot Water Controller uses little power, has low insertion loss and no bulky wasteful transformer. It’s 97% efficient! (pass through)

The recommended minimum 2 panel 440W system (must have MPPT) gives you a little more than that and is a good economical trade off between grid power, solar costs and precious roof space used, if you go too high in watts the thermostat may click off more and then you are wasting your investment in solar panels. Everything you put in via solar adds up all day long and monthly!

750W (3 panels) has been getting good results for customers, you should use the bigger box. As you go with even more panels wired in SERIES the open voltage goes up so you should use a professional electrician for the wiring part.

For a 2 panel recommended minimum system, it fits in this Eaton low cost UL Listed electrical disconnect box available at Lowes or Home Depot for $8 (not included because you pick the box size and should buy one locally to save money on shipping). You get a disconnect switch, wire connection terminals and a nice enclosure with no extra shipping charges!

Heating elements run at a lower wattage with less stress and will last longer. Higher voltage means lower cost wire and less power loss over long runs.

Can be used on a small electric “pre-heat” solar hot water tank for use with a gas water heater.

“Smart” Meter Ready. The so called “Smart” Electric Power Meter is notorious for not reading “backwards”, meaning if you pump power into the grid with a solar grid tie inverter they will still run forward.

The Solar Hybrid Hot Water Controller sends solar power directly to the heating element which reduces the power you use from the grid for hot water. You now have solar electric energy without power company contracts or hassles.

Solar panel daily watts = watts off your power bill. Less grid power usage, lower bill.

You can buy a more expensive UL Listed electrical box on the Internet or a local Electrical Supply house, your choice. The bigger the box, the bigger the heat sink if you plan to push more watts for some reason.

The Eaton box gets slightly warm with the 2 panel recommended system and warmer with 3 panels, you should go to the bigger box when over 600W. See our “Other Enclosures Page” for more info.

No moving parts (such as a fan), it works quietly and efficiently day in and day out without maintenance hassles.

Winter efficiency does not decrease like fluid based systems. No heavy collectors on the roof, just lightweight solar panels.

Fluid based systems also have a grid backup element for dark cloudy days. Many of the standard fluid based systems are equivalent in actual energy put into the use tank as a 750W PV system.

Continues to work even during grid power outages and light cloudy days due to MPPT technology. No copper piping changes, soldering or expensive pumps to wear out.

The device comes as a partly assembled kit

The solar hot water circuit is fully assembled and tested and comes mounted on it’s heat sink as shown to the right.

Depending on the number of panels you will run, you pick a box from Lowes, Home Depot or a local Electrical Supply house, buy some plywood, mount it & wire the unit. No soldering required.

The box and plywood are not included in the kit.

A controller and Eaton or bigger box may be available from our dealers, if you don’t mind paying the extra shipping or don’t have a Home Depot or Electric Supply house nearby.


Take a look at our extensive and long winded Solar Hybrid Hot Water Controller FAQ page. Skip to the Technical Specs below or scroll further down.

What else can you buy that will keep on giving you a return for 25 to 35 years+ after you recoup your initial investment?

Any power reducing modification on a piece of real estate will increase the property value.

One of the biggest energy users in your home, next to heating and cooling, is your hot water heater!

You will now own something of substance and value instead of throwing money year after year into the power company black hole!

Reduce your carbon footprint now! Reduce reliance on foreign oil!

The “future” all electric house is now possible and efficient!

The Solar Hybrid Hot Water Controller is assembled and made in the USA! Your purchase helps support local American electronic assemblers, parts suppliers and machinists. It’s a shame but you can’t get electronic components made here, so some components are from other countries. But there are USA side electronic distributors, parts and metal manufactures we buy from.

A Few Customer Reviews And Installs

“I installed one of these devices several years back and it has operated flawlessly since then.”

Jim, Ohio.

See Jim’s YouTube Channel and other videos 2+ years back show power savings, like this video.

“Checked at noon water temp at tap was 128 so don’t believe the upper element came on during the day.” “Excellent product and extremely helpful input for installing.”

Mark, VA – (480W of panels, 80ft #10 wire, added amp and volt meter)

“Today I am impressed. I got to 134F under cloudy skies. Outstanding!”

Joe, NM – (448W of panels, pre-heat tank for gas water heater)

“My system is working great. Temp was 142 yesterday which is about 10 degrees above where thermostat was set. This is right on because that is sensing in the bottom and heat is rising and collecting in the top which can easily be above that lower thermostat setting.”

“I have had the breaker to it off since installing so no top element is on and plenty of hot water.”

John, TN – (690W 3 x 230W of panels, bigger box for heat sink)

“It’s working good!”

Mark B, MT – (750W 3 x 250W of panels, bigger box from old power supply for extra heat sink)

“The controller works well and maintains the hot water tank between 50 to 70 degrees Centigrade, except on overcast days.”

Ian, Queensland Australia – (122F to 158F with 540W, 3 x 180W panels)

“Looks like a great invention!!”

Ed, CT

“Dual unit for both upper and lower elements for pre-heating a high usage system.”

TL, NV – (1500W total 6 x 250W of panels, larger 12x12x4″ UL approved box for extra heat sink)

See what Sunetric has to say about PV Electric for Hot Water in this White Paper, they are a Solar Systems Installer for Hawaii, Colorado, California, Pennsylvania and Washington D.C. (lots of charts here too, remember that we are suggesting to only boost your hot water needs to be more economical and cost effective unless you are ready to install a big system or go off grid): – or – (via

Buy it with confidence on Ebay!

EDITOR: this does not seem to still be available on eBay, there are a lot of old and dead links on his page.



  • (Get a box at Home Depot or your local Electrical Supply)

  • GLOBAL SHIPPING is available via Ebay!

If you have problems with that eBay link, please Contact Us with your zip code, country or other info if you can’t find the item listed. Alaska, Hawaii, Puerto Rico, Guam, or the U.S. Virgin Islands contact us first because eBay calculates shipping wrong for you.

Buy it from your local Solar Dealer or Installer!


Suggested List Price: $299.95USD (without box) Dealers may have discounts or specials (this is not a mass manufactured consumer item you can buy at walmart)


Commodore Australia – Home Solar / Wind Systems Dealer: Solar Power & Heating, Generators, Batteries, Wind Turbines, Solar Farm Electric Fence Equipment and more in Euroa, Vic, Australia and the surrounding areas. Ships to all of Australia.

Phone: 03 57951567, 0408 619 779 International +61 408 619 779

Practical Preppers – Home Solar / Well Systems Dealer & Installer: Residential Solar / Wind / Well Systems. Offering complete systems ready to go. Off grid and preparedness is a specialty. Serving South Carolina and the world via their ONLINE STORE at Practical Preppers

Phone: (864) 915-1855

Thank you for your business!!

Unusual orders, custom designs or special needs, please Contact Us.

Solar Installer inquires are welcome.

Specs for TechLuck-SHWC-1:

Please also read the FAQ

  • Absolute Maximum Voltage: 250V DC (panel open circuit should never approach this)

  • Max Operating Voltage: 200V (operating means when panels are under load)

  • Max Operating Current: 10A (larger box / mount to extra heat sink required for max amps)

  • Typical Operating V&A: 70V to 170V at 8A (only voltage goes up with more panels)

  • Max Panel Watts: 1280W Solar Panel “sticker” Watts (you don’t need this much! FAQ)

  • Solar Panel Wiring Configuration: Always in SERIES (voltage up, amps the same)

  • Insertion Efficiency: 97% (pass through)

  • Switch: High tech, latest technology IGBT (mosfet) 80A at 1200V (over designed)

  • IGBT Gate Drive: 15V, hard off/on for maximum efficiency and quick switching

  • Microprocessor CPU Controlled MPPT with constant adjustment

  • UL 1741 compliant when using a UL Listed, NEMA rated enclosure and metal conduit

  • NEC Article 409 compliant when using a UL Listed, NEMA rated enclosure (FAQ)

  • Recommended MINIMUM solar panel wattage, unit in box: Around 440W (2 x “24V”)

  • (“48V” panels will generally MPPT at 60V to 70V depending on the model)

  • Heating Element: Standard 240/208V 4500/3380W or others tested, see [tests page below]

  • Works with the original factory AC thermostat.

  • Load Type: Resistive loads only (no reactive loads like motors or anything with coils)

  • Wire Size: 12 AWG minimum to the element, BX cable, 5 ft max length, shorter is better

  • #10 AWG from panels in most cases is best (depends on the voltage you are running)

  • Must be mounted in a Eaton box or other larger box/piece of metal for a extra heat sink


  • This is a transformerless device. No loss through a transformer! No winding short/open.

  • Controller Size: 4.5″W x 4.5″L x 1.5″H

  • Always use a thermostat on any element! For indoor use only. Not for use with batteries.

  • A professional installer or electrician should be used for any install.

  • Always GROUND your solar panel frames for lightning protection.

  • Always use metal conduit (also grounded) for wire runs and stranded wire for DC.

  • These specifications are subject to change without notice.

This is a low voltage DC off grid device not connected to the electrical grid “mains”

  • Eaton Disconnect Box: (Home Depot lists them retail for $8, purchased separately)

  • Note: Controller fits in this exact box perfectly without any modifications or drilling

  • 60 Amp Non-Fusible Pull Disconnect Model: DPU222RP

  • UL Listed: 74X2 #E132354, #E143893, #E196365

  • CSA Listed: File 069743 (DH222R)

  • ANSI certified

  • NEMA Rating: 3R Enclosure

  • Suitable for CSA Type 3R applications

  • Meets 2008 NEC Article 422.31 (B) requirements for servicing electric water heaters

  • Copper or Aluminum wire rated (AL or CU Wire)

  • Canada Alternate Model: 3GAC222NF

  • Box Depth (in.) 3 in

  • Box Height (in.) 9 in

  • Box Width (in.) 5.5 in

  • Do not buy the GE box that looks the same, it’s too small inside and the controller won’t fit.

As you add more panels you connect them in SERIES. Make sure your OPEN VOLTAGE is well under the ABSOLUTE MAXIMUM VOLTAGE. Operating voltage is always lower than the Abs Max and please don’t push the specs, this isn’t a car you can “soup up” or CPU you can overclock. Please read the FAQ.

Always GROUND your solar panel frames for lightning protection. Always use metal conduit (also grounded) for wire runs and stranded wire for DC. Recommended additional safety devices you can add are a Lightning Protector, and at higher operating volts over 80V, a DC Ground Fault detector and a DC Series Arc Fault detector (when they become readily available and reliable).

Off grid hot water configuration works well with low use and low wattage VIDEO

Contact Techluck for special situations or custom designs.

As an option, you could keep the upper grid powered element from coming on during the day using a simple electrical timer available at Home Depot or Lowes. This would help keep the upper element off and let the solar panels to do their thing in the daytime, saving even more on your power bill. Also solar hot water helps if you have high Time Of Use tiered power pricing.

A little solar story

When I first started to want solar hot water I considered piping in a water type solar collector from outside. Then I watched videos and e-mailed a few people that did that and found a few problems.

First, if you don’t put in some sort of system to drain back the water you are going to have freeze problems and possible panel damage and leaks. Setting that up is not fun, you have problems with air in the system. It needs to be designed to totally drain or it will still have problems. And it still costs a lot and gets complicated. More stuff to worry about in the winter.

The other option is to drain it every time the temp drops. Well, if you do that, there goes free winter hot water and what if you forget? I like simple and automatic stuff I don’t have to mess with.

And then there’s the plumbing, all over the place, maybe a 2nd exchange / heat storage tank that will develop leaks later as any tank does. And a pump that wears out or gets clogged. It’s a maintenance nightmare and still a costly install.

So a system with solar electric PV is the only way to go. Wires are easy to run.

At first I tried to connect my solar panels direct to the element. But the mismatch without MPPT in the morning and afternoon is brutal, the panels are nowhere near their Max Power Point and you get little total daily heat that way unless you have the extra space and want to throw lots of panels at the problem and just say “oh well”.

Another choice would be to change the element. Have you ever seen the nut size on those things? What if I screw up the threads? Will it leak later? Do I really want to mess with a perfectly working expensive tank?

And without MPPT, you still have a mismatch in the morning and afternoon anyway, doesn’t really get that much better for all the hassle.

So I designed the Solar Hybrid Controller using MPPT and love it!! You will too!

It’s super simple to install with few components to go bad and just sits there quietly and works every day saving me money with no worries and little up front cost.

The idea is — how simple and hassle free can it be? And in the end does your upper element come on less for a total installed system cost of around $700?

That beats most of the other systems out there. All DIY, easy install with no plumbing nightmare, no soldering, no leaks and no worry of freezing. Almost anyone can wire up 2 wires.

Installing wires instead of pipes is much easier, and it gives me other options, like if the grid goes down during a bad emergency I can say heck with hot water and simply re-configure the panels for 24V by switching a couple of connections at the panels (or even inside depending on how I wire things) and have more power for my emergency back-up inverter and batteries.

Simple is better

Other stuff

Your hot water heater is one of the biggest energy wasters in your house.

Go solar! A solar hot water heater is a good way to go. Little panels on the roof and away you go! Savings because the power is free from the sun!

You will be able to save a great deal by further investing in a timer for your water heater. Set the timer to turn the grid connected electric water heater element off during the day when solar is heating it. Then set it to come on again late at night so it can recover to a set point and be ready for the next solar day.

Another way to save with your water heater is by draining it on a regular basis. Unless you have soft water, it is important to drain a couple of gallons of water from the bottom of your water heater at least two times a year. This is because hard water deposits can collect on the bottom of your water-heating unit, surround the heating element and reduce efficiency.

Since the water from your water heater is used primarily for keeping yourself and your belongings clean, there is no need for you to use water that is heated to 150 degrees Fahrenheit or above. However, most elements on electric water heaters are preset to at least 150 degrees.

Not only is this dangerous, but it is also a waste of energy and money. We recommend you reset your electric water heater upper element to 125 degrees F. (keep the lower solar element turned up and store energy)

You may also want some batteries, a solar controller and solar panels for emergency power back up in case the grid goes out for things like lights, TVs and radios. You can also Grid Tie any excess energy that isn’t going to charge batteries. It’s fun and it’s priceless to see your power meter actually turn backwards!

The Solar Hybrid Hot Water Controller is Patent Pending.

Some TV people are calling Solar Panels a Solar Generator, watch out for the low power, over priced “as seen on TV” systems out there. Solar Panels are currently available for $1 a watt shipped to your door, look around!

MPPT Solar Hybrid Hot Water Controller Load Tests

Also please read the FAQ in the link at the end of this article.

We have tested a number of different water heating elements in several configurations.

4500W 240V Water Heater Element is the “standard” and recommended element for USA tanks

Tested up to 1280W with the bigger box. Can work down to 500W, read more below for somewhat more efficient solutions at lower power levels.

3600W 240V Water Heater Element is another “standard” in many countries

It needs at least 900W minimum with the bigger box. Another common element is 3000W 240V and is way too high ohms to do you any good, you will need to change it out.

1500W 120V Water Heater Element (Home Depot) using 400W of “48V” configured 12V series connected solar panels, meaning 84V open circuit max. and also up to 750W (3 x 250W in series and bigger box)

MPPT worked perfectly with the standard Solar Hybrid Hot Water Controller as shipped. Total daily power output to the water is only a little more efficient (mornings) than a standard 4500W 240V element but may not be worth the drain and change out of the element for 750W input.

Note that 1500W elements are found on some smaller size tanks that use 120V. This was mostly a low power test at 400W for people who want to run a small tank, like maybe 20 gallons. The 750W test (with bigger box) shows that you might get a little more power in the mornings etc.. on a bigger more normal tank, and the heat-sink temps are still within limits.


2000W 120V Water Heater Element (Home Depot) using 500W (2 x 250W and Eaton box only)

MPPT worked perfectly with the standard Solar Hybrid Hot Water Controller as shipped. Total daily power output to the water is a little more efficient (mornings) than a standard 240V 4500W element but may not be worth the drain and change out of the element. Note that 2000W elements are found on some smaller size tanks that use 120V.

This was mostly a low power situation at 500W for 1 person who does not use much hot water. Working on a 50 gallon tank for months (still going).

500W is great with this element for low very conservative use in a more off grid situation, like using a generator or grid with a MANUAL, HAND PLUG IN (2 socket setup, one solar side) for more than a few bad solar days, connected to the normal top connection on the tank so the upper element comes on first, both elements changed out.

This element will also work on a small tank, like 10 gallons, with only one 250W panel. Although not very efficient, tests showed a 16F rise in 7 hours on a well insulated tank. Why 7 hours? The single panel got shaded at 3PM for this test. For a off grid cabin with low use this may work for you.

WARNING – DO NOT GO ANY HIGHER WATTAGE THAN ABOUT 500W WITH THIS ELEMENT!! This means DO NOT TRY IT ON 750W – The controller gets too hot! DO NOT GO THERE EVEN WITH A BIGGER BOX! You don’t need to do this at 750W anyway so DON’T DO IT! You want to smell smoke?

200W 12V Immersion Heater for RV or a 200W 12V Car Heater using 200W of “24V” solar panels, meaning 42V open circuit max

This was just an experiment but the fan did run at about the same speed as normal. These heaters are sold to defrost windshields on cars where the defroster isn’t working and plug into a car cigarette lighter socket. MPPT worked perfectly with the standard Solar Hybrid Hot Water Controller as shipped.

Due to the lower voltages, a really good larger heat would be needed, like a 1/16 thick or better metal plate backing the Eaton box (box flattened in back) to increase heat sink area when using a 12V element, there is a heat issue and more wattage input will over temp the unit!

This was only for testing. Please do not do this with the standard controller. If this is truly your application for the SHHWC, please contact us and we may be able to build you a custom unit for this special application.

If you use your imagination and a little creativity in special situations you could maybe use a space heater (like the car heater above) or other resistive element device (with only a heating element, no motors) to heat things, like maybe heating a horse water trough or barrel to keep it from icing over in the winter.

It doesn’t have to be water that you are heating. Please contact us and we may be able to build you a custom unit for special applications. Please contact us before doing crazy things, you don’t want a dead controller and we don’t want to have to fix it.

Remember that all of the above tests were not done for a extended period. Meaning it’s up to you to monitor heat sink temps when increasing wattage or doing experiments like the above ones.

The best tested setup including customer feedback is the recommended 4500W 240V standard water heater element and a “48V” set of panels (minimum setup + grid backup), or 750W (3 panels in series + grid backup) with a bigger box for more heat sink area. Do not exceed the Solar Hybrid Specs!

Please read the FAQ.

Always use a thermostat on any element! A professional installer or electrician should be used for any install.


  • Very simple design, stick to instructions and can last a lifetime or more

  • Easily replace any components that may fail by any electronics technician

  • 100% off grid function, requires NO POWER to run device

  • Simple flashing LED when working

  • Compact with minimal wiring, 2 wires in, 2 wires out

  • Saves you lots of money in the long term


  • One man operation means limited support and product could disappear for sale at any time

  • Protected code to run the MPPT function (can easily be reverse engineered including PCB)


  • Does not reflect good value for money on initial purchase

  • Money better invested in a quality heat pump system

  • Does little when cloudy, and next to nothing with heavy cloud


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