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DC bricks are unreliable, expensive and get too hot. Building your own with FET or IGBT is the only sensible option.

You can not look at panel voltage to determine if there is enough sun to run the pump. This varies too much with load current. A small loaded solar panel (like from a garden light) or a photo resistive cell must be used to determine sun intensity. Unless you only want the pump to run for two...

This circuit switches in a second or third heating element when a fixed current is reached. This forms a pseudo MPPT if enough elements are used. A LM358 amplifies the voltage developed from a 50A 75mv shunt to a reasonable level. Second opamp is used a a comparator with positive feedback for a...

In my particular case solar thermal would be near impossible to do. 70% of my panels are shaded at any time. There just isn't any place that gets sun long enough. Solar thermal generally has large tanks that circulate. The means heating an entire tank. I use small tanks. Primary is 4...

That is a much improved design over the first one eliminating the fan and external power supply. It still doesn't have arc interrupt which would allow heaters to be daisy chained using mechanical contacts. Thermally stratified tanks are the way to go with PV so the top of tank can heat quickly...

Just what is your budget for this?

Perfectly fine to use just a light switch with this system. Both heaters run in parallel to get a low enough resistance. It used to have jumper cables to restore batteries. Switch was to limit charge current. The sticker covers a hole in cabinet. I have two water heaters in series, you might...

This is another nice contender I use...

Another new entry into the PV water heating market from another Polish company, Green Boost 3000 by a larger company VOLT POLSKA. I've been told it is about $300. It has two outputs with one having priority. Output is a H bridge like a MSW inverter...

When you try to draw more amps than the panel can supply, the panel voltage drops. When panel voltage drops, it tries to draw even more current. Hence a death spiral. The boost converter won't necessarily die from that. If the specifications are read carefully there is a limit on the input...

Solar is seldom the deal they think it is.

Everyone should watch Power Trip 2003 about electric power in the Republic of Georgia. The electric service does look like that picture was taken from the movie. I think you can watch it on Amazon. This is the movie trailer.

If the controller is shorted, that will drag the panel down to battery voltage. What kind of current are you seeing?

No, the quote is " Never trust anyone over 20" from the cult classic movie WILD IN THE STREETS (1968). Rubin even mentions this in his book Steal This Quote.

Everyone likes to think their particular situation is the only one in the world. Going higher temperatures lowers efficiency and non CO2 systems have a hard time achieving the higher temperatures. Running higher temperatures at times of the day when excess energy is not available does cost...

I had a dryer element burn out and I had a new resistive element I had picked up at an auction. Put it in and wife said the cloths were,t dry after an hour. It was a 2,000W element and I was supposed to cut it down to make a 4,000W element. I added a 50% duty cycle timer in series with the...

It amazes me in this digital age how we still cling on to ancient power technology of sine waves.

Many water districts have been sued when water drained out of tanks due to a main break and elements then burned out. It is common to see weeping of the over temp valve. Yhis is due to expansion of water with no place to go. Pressures can easily go to 500 pounds unless you have some leaking...

Those measurements were made from a power meter on the 12V going into the inverter. I used a 200A shunt to handle the 120A surge with a $10 50A power meter in parallel. That calibrated to a 8.6 power multiplier. Usage can change that. Don't try putting in new groceries at 4pm or it won't have...

Nobody ever posts the results they get with direct connect. I'd like to see some total weekly power readings that can be compared with a solar calculator. Just ambiguous stuff like stuck my hand in the bucket and it was hot. It will be raining all this week and I still need hot water. I use...

If low power, it is likely the capacitors failed. They can be worked pretty hard in this application. I'd put some in parallel with input power externally. A semiconductor failure would cause it to not work at all.

That little extra voltage won't do much harm if the inverter isn't overly pushed. The trick is to fool the inverter into thinking it is at a lower voltage. Many older MSW inverters have a switch to turn it on and off. Two wires go to that, one to the +12V terminal and the other to the control...

Schottky diodes typically have low forward voltages up to about 40V rated inverse voltage. Forward voltage is also lower when they run a bit toasty.

This is ideally what you want to have to operate in parallel with a MPPT controller that does not use up battery or inverter resources, automatic diversion to a water heater or anything else like a space heater. Sorry, water heaters need to have thermostats and controls to make them efficient...

Panels have a fixed current limit. The idea of a fuse to protect charge controller from panels is ridiculous. The fuse will always be a higher current than the panels can ever supply. A fuse may protect panel wiring from the battery should a controller fail. A fuse is a nice disconnect for...

It is astounding the resistance to technology in solar and the encouragement given to remaining technology backward. I just watched a video that was 5 minutes long with this guy up on a ladder switching solar panel connections to adjust for the weather heating his water. That is keeping it...

If you have just two panels, they will never go into bypass mode because there won't be enough voltage to charge a battery. Bypass diodes don't fix a location problem. They are only to protect the panels from excessve reverse voltage.

Fact is that a water heater just can't absorb that many excess KWH a day. Many use only 5KWH a day. The higher the temperature, the higher the heat loss. Typically about 1.5KWH a day. With grid tie it is easy to monitor when excess power is going to the grid. Wham bam on off diversion controls...

There was a documentary years ago on the grid in Georgia called Power Trip. Note there is some other crap movie by that name. It makes you wonder why they have any power at all.

Don't show that inverter output to the inverter company or they will never listen to another thing you have to say. You have a floating neutral. That is totaly the way I would expect it to look given the way you measured it. That should be measured thru a transformer.