How many amps can you make?

I can have any number of solar panels that would deliver 80 watts each at a voltage of 60 D.C. I would like to connect to the panels a couple of pedestal fans that would work directly and also a hot plate for cooking for lunch. Main problem is the higher D.C.Voltage generated.

You just need a transformer to drop the voltage from 60vdc to 12vdc....and certain appliances can take variable power input, resistance heat for the heating plate would work, but you would need about 600 watts, cheaper to go alcohol...variable speed dc motors for the fans 120 to 200 watts...

So where you going to find a DC transformer at?

Any transformation from high to low, D.C. to A.C. involves loss of energy. In one of the forums it was stated that when 230 V A.C. is transformed to 12 V D.C. for computers etc., the losses could be as high as 40%.

Taking this as a cue, I don't want to change the voltage at all. I want an appliance that would work directly with the 60 V D.C. generated.

I wish that some one would guide me to the source of such.

"Any transformation from high to low, D.C. to A.C. involves loss of energy."

True, but that goes for any energy transformation, including (just to be pedantic) the conversion of solar into electricity with PV panels

"In one of the forums it was stated that when 230 V A.C. is transformed to 12 V D.C. for computers etc., the losses could be as high as 40%."

Again, true, but incomplete. Modern switch-mode power supplies often exceed 80% efficiency. (This certification lists several HP units testing at better than 94% for certain conditions.

"Taking this as a cue, I don't want to change the voltage at all. I want an appliance that would work directly with the 60 V D.C. generated."

Well then, you might just need to design and build them yourself.

As other's have already mentioned, that 60 VDC is most likely the open circuit rating. Put a load on it and you should measure a markedly different value.

No, switching-converter losses are on the order of only 5 to 10% for the better designs. For applications using under 100 watts, low-cost buck-converter ICs exist that can do the job. The LM5116, LTC3810 and LTC3703 are three controller ICs that can down-convert up to 100V and are nearly 95% efficient. I'm sure there are many more (there are lots of ICs rated at 75V, but that's a bit too close to your 60V expected value).

These ICs are called controllers, because they drive two external MOSFETs to do the actual switching. This means the finished circuit can handle very high currents, if you choose the right MOSFET.

An alternate to the buck converter is a flyback converter. This uses a controller IC running at low voltages, and an external (or in some cases, internal) high-voltage MOSFET to run a flyback transformer. The transformer has a low-voltage output winding, e.g. 1/5 as many turns as the primary. The advantage of this approach is the huge range of available low-cost, easy-to-use controller ICs, meant for the AC offline power-supply market. Some of them are quite efficient. (Hah, I'll bet that by changing just a few parts, you could press a spare computer power supply, with its 12V output, into service for the task.)

By one of these means you can convert your voltage to 12V (or 24V), where you'll find a host of appliances that you can power (think of the RV crowd). As an added advantage, the voltage will stay at 12V even if your input sags.

Most circuits take some minimum amount of operating current, which means their efficiency appears to be degraded at low load currents. Someone may have gotten the 40% loss numbers from data at these low load currents. IMHO it's better to plot power loss in absolute terms, like watts, than to plot a percentage efficiency at low currents.

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Since when did transformers work on DC?

A DC regulator is a better way to do it...there are also linear chips around that can produce any DC voltage down to 2.5 volts from 60VDC..

I personally would make a mains inverter, to convert DC to AC mains voltage, you have enough power.......then I could use it with normal mains products.....

What kind of panel puts out 60 volts DC, and if they do, why not just put them in series and enjoy the world of 120 VDC appliances. Using solar photovoltaic for heating is a bit crazed. Ever heard of solar ovens? Solar thermal water or oil heating systems driving ammonia-based refrigeration? Dometic or Arkla?

I did hear of Solar cookers, which were vigourously advertised appliances in India. Many bought them and they are just occupying their safe place in the attic now.

Main difficulty is that they cook when the sun is at its hottest. Second thing is they require orientation towards the sun every few minutes, Thirdly they are useful for just boiling and not for frying and fourth and most important thing is the that the cook (Usually in India, the housewife) has to stand in the hot sun to do the cooking.

When I advovated Solar Photo voltaic appliances to do cooking, I had all these in mind.One can comfortably do the cooking from the shade. Cooking need not be restricted to just boiling; even frying could be attempted. When the power could be stored, even dinners could be cooked in the night.

Thin film solar panels give 60 Volts D.C.power, as against mono/poly crystalline Silicon, which produce 12 /14 V D.C.power. These panels have the ability to work satisfacorily in diffused sunlight, unlike MCSi/PCSi panles.

In my original question, I had typed wrongly 60 W D.C instead of 60 V. D.C. and perhaps that is causing the confusion.

Now it is upto the discerning forum members to fire their views at me or alternately give me some help.

With conventional resistance heated cooker tops, you can use DC or AC to run them, though control of the temperature may be a problem (I don't know how they are controlled nowadays, but if say PWM, it might be possible to adjust/change it to use DC).

Perhaps someone could update me on that point.

If its an old cooker, that may still work with DC....with careful thoughts first....

"I can have any number of solar panels that would deliver 80 watts each at a voltage of 60 D.C. I would like to connect to the panels a couple of pedestal fans that would work directly and also a hot plate for cooking for lunch. Main problem is the higher D.C.Voltage generated."

Ok, assuming you can solve your other technical challenges, here's the bottom line(s).

1: Appliances are made to work on industry standard voltages, because the economies of scale dictate that. So at AC voltages, that boils down to 120V or 230V, the tow common household AC voltages across the world. Then once you get to DC, the volume is in appliances that will work on battery powered mobile systems, the largest group being vehicles, almost all of which use 12VDC. There are a slowly growing number of 48VDC systems being used, but I doubt there arevenough for appliance mfrs to warrant the extreme expense of developing motors for them yet, although you will find some industrial grade motors if you want to make your own. After that, you are fully into industrial DC voltages, but not common appliances. So figure on adapting to 12VDC, or inverting to AC. You are not going to find oddball DC voltages on appliances.

2: Watts are watts are watts, the voltages are just details when it comes to use. So if you have 60W of useable power for a cooktop, you had better plan on EXTREMELY slow cooking! To get an idea, plug in a 60W light bulb and start frying an egg in a pan above it. You will get the idea. Same with the fan, even a SMALL desktop personal fan is more than 60W. So yes, you are going to need a LOT of those small panels in parallel if you want any useable power out of them. A better plan is to use them to charge a battery bank, so that you can STORE energy for later use. That way you are trading power for time.

Connecting DC panels directly to a hotplate would be simple. A hotplate can be made to work (at least temporarily) on AC or DC, provided it has only an on-off switch, or if it has a thermoswitch that causes the burner to cycle on and off (a fairly common arrangement) for temperature control. Electronic controls provided with many standard units would not be expected to work... although some could. However, even the on-off switch is unlikely to be rated for DC use.

About 20 of your panels (1600 watts) would be required to power one burner. Therefore, you should wire the panels to produce a voltage that is standard where you live. For example, wiring four panels in series would produce 240 V. 5 groups like this, wired in parallel, would then produce adequate amperage for cooking.

I can't see any advantage to running anything on 60 volts. Why would you want to do such a thing? This just drives your cost up dramatically.

Assuming a standard voltage, cooking would have to slow down when the sun goes behind a cloud, of course. (Thin film panels reduce their output by slightly more than half when the light intensity reduces by half, etc.) There are numerous other problems that can be encountered when voltage and wattage varies (as it does with solar panels) in trying to power a range of appliances. That's why virtually every solar installation is either grid-tied or uses batteries to enable the use of standard appliances.

Some pedestal fans (and power saws, electric drills, etc) can work on DC power. (They need a "universal" motor to do so.) Here, again, there is a huge economic advantage to using mass produced appliances, rather than ones custom built to an odd voltage.

In many countries, there can be legal and liability issues to deal with if you power appliances in non-standard ways. At very least, you have to be sure that a standard appliance cannot be plugged into the non-standard source. Because DC does not pass through 0 volts frequently, switching and fusing are different, so each appliance would need to evaluated by an expert.

None of this would work early in the morning, late in the day, or at night, of course. That is why so many off-grid installations have batteries. A simple inverter then enables any standard appliance to be used at any time, in the way intended, without any worries about whether your insurance will be in force when your house burns down. Things with induction motors work correctly, without having to replace the motor with a universal motor, etc. etc.

In the US, having a company build you a custom voltage appliance is effectively impossible. The certifications, etc. are just too costly. This would be true in most places in the industrialized world.

Beautiful situation summary Fry.

Something for the OP to think about and possibly refer to in order to make some rational decisions.

If the solar panel output voltage is 12 volts, go to Amazon.com and do a search on 12 volt appliances. There are many appliances made to run off car/truck 12 volt DC systems. You'll have to look at the details to see which use 5 amps or 60W.

For a starter are you talking 60W or 60V?

If it is in fact 60VDC, are you measuring that or reading it off a document/nameplate?

As already pointed out, there are all manner of 12VDC appliances available. They are not cheap.

Have you considered using an invertor?

Looks like a bit of additional homework is called for. This forum plus others has presented solutions that address every objection posted by the OP.

Lowtechmagazine has published extensive article of a german design for a solar cooker where the cooking is done indoors. Gizmag recently published the result of a contest for solar cookers that can be used at night by storing the heat collected in daytime. 10 designs were shown. Using PV to drive electric hot plates is about as inefficient as you can get.

I suspect the 60VDC is the open circuit rating and when full load is applied the voltage takes a big drop. The suggestion to series connect 60V panels makes a lot of sense. I know of a charger / power supply that will take 120V DC to drive DC loads and it is made in India. No doubt other brands are also available.

OP needs to do some research.

"I know of a charger / power supply that will take 120V DC to drive DC loads and it is made in India. No doubt other brands are also available."

It's not often recognized that ordinary cheap offline power supplies (especially the older lower-power types that are not PFC, or power-factor-corrected) work fine with DC-voltage inputs. They use a bridge rectifier to charge a "bulk" capacitor, and then work with the resulting DC voltage to create a 12V output voltage, etc.

You'd want to select one of the dual-voltage versions that work from say, 90 volts AC to 250V AC. That means these need square-root 2 = 1.414 higher DC voltage, or about 130 to 350 volts DC input to work properly. Certainly series operation of power sources is required. But that's an attractive wide 2.7 : 1 operating range, which is very useful for adhock power-conversion lashups.

For example, this 460W CoolerMaster supply available from NewEgg for $40. You can just apply your DC voltage to the AC-input cord. It's not even necessary to pay any attention to the polarity!

p.s. Using a DC input of 165V with DC current measurements is also a great way to test the power-consumption of older-style AC power supplies.

1. 5 12V 'modules' in series make a 60V 'panel' OR Sharp makes single 36V modules. 2. Lead acid battery, contrary to your 'expensive' remarks, are superbly recyclable. Could you expand on what is so expensive about a battery when you will pay for a custom item instead? Under a good solar controller I have had 3 year life become 6+ years. 3. A single 235 W, 24V module and small controller with battery opens up the world of 110V inexpensive appliances. 4. Using a battery or two (marine deep cycle Walmart variety) you or I can cook eggs and small individual servings in moments rather than hours with a cheap 600W AC microwave. 5. You are the questioner, therefore, to get the answer to your own question you must buy and try. My feeling is your criteria are the nexus of your problem. 6. The loss of efficiency using solar controllers is far more efficient than trying to earn money for a "custom" solution of dubious lifespan.

Why are LED lights to be run from a solar panel without battery storage? Why are the LEDs wanted 'on' only when the sunshine is 'on'?