can i use a solar panel without using battery

[billvon]

Option A sounds very interesting. Will the straight grid tie type inverter see the output of the battery backup inverter as the nice stable utility so it will agree to stay hot?

Within limits - yes

What is the interface? Just tie them together at the load side of the AC panel and the slave (conventional grid tie) syncs to the master (off grid battery backup inverter) and shuts it self off if the master goes down because of low battery voltage?

It is hard to use a completely conventional off grid inverter for this because they cannot sink power. Something like a Trace SW or an Outback GT inverter is a better idea since they will sink and source power, and thus can absorb some of the 'excess' power into the battery bank. This is called AC coupling. You also need to be able to regulate AC power to the inverter, something that a straight grid tie inverter can't do.

Here's a paper on the idea: http://www.outbackpower.com/pdf/tech..._WHT_Paper.pdf

[analogmanca]

Ok, I wont get into a argument with the experts on what cant be done so I will just make this one post, and leave it to others to find out if its so or not, but I have done it and more. Its called shunt regulation. In fact I have been using a shunt regulator ( have built a few kinds) for 4 years off one of my turbines, a otherpower style one, with capacitor support, and battery backup (but real small battery)
It fact I cant say enough good things about it. the shunt is always on the mill rather than having a dump load that has to be switched on. I feel this is safer. The shunt regulator I am using now has a range of play (12.5 to 17 volts up to 300 amps) and is not a problem for my exanetrix, but rotary inverters that I put up pics of work too. I am changing my whole system around to work with this( panels and mill) my needs are modest (3 kwhrs/day) and am incorporating load sheading ( as needed)into my plan so I dont have to have a large bank. 6 t105s is my goal, with never more than 25% discharge.
Anyway, Experiment, and try out different things you may make some discoveries on the way ( PS, I am fully unqualified in anyway,no initails after my name, only know what works for me)

[russ]

Discoveries? Personal discoveries possibly that would have been cheaper and easier to read about.

[Sunking]

Its called shunt regulation. In fact I have been using a shunt regulator ( have built a few kinds) for 4 years off one of my turbines, a otherpower style one, with capacitor support, and battery backup (but real small battery) It fact I cant say enough good things about it. the shunt is always on the mill rather than having a dump load that has to be switched on.

Shunt regulators have been around as long as the transistor. They work but extremely inefficient. They work by basically shorting out the power and burning the excess off as heat, just like a dump load. With a dump load you can at least utilize the heat, but with a shunt it is just wasted. That is why manufactures do not make them anymore.

[jlvs]

Grid tied solar electric during grid outage.

So I really appreciated this explanation from TnAndy but I wonder about another approach and its interaction with the solar powered system. I live in Thailand where we have lots of solar input and I can get a grid tied solar setup rated at about 4.8 kw for a pretty reasonable price out of China. The power grid here is actually pretty reliable, but we do have the occasional black out. I really do not want to go to a battery system so how about this? If the grid power goes down can I place a backup generator in the system with a grid disconnect switch and fire up the generator to produce temp power. The rest of the question is: 1. does the back up generator pose any risk to the inverter or solar array? and 2. If it were a small. lets say 500 watt generator, and the power fed back through the load center box and then to inverter would the solar panel power be additive to the generator power? So 0.5 kw from the generator and at noon about 3.5 kw from the panels, would this make available about 4 kw to the home and would the inverter start working sensing the feed from the generator. I understand the importance of having a grid disconnect switch for safety. Does this system make any sense?

Why would you burn 7 light bulbs in the day time ?

What you haven't picked up on is the batteries, or the grid, level out the power supply.

Panels don't produce a nice, even steady flow of electricity like a generator does ( heck, even they bog down when you load them up )....a fixed panel produces a little at sunrise, then the most around noon, then tapers off again in the afternoon as the sun angle falls away from perpendicular to the face of the panel. Also, weather conditions GREATLY affect the output. Cloud moves over, output falls WAY off.

In the case of incandescent light bulbs, say a cloud moves overhead.....they would simply dim. But what happens if you're using a motor ? Brown out....or your system tries it's best to pull it out of the small battery bank.

In a IDEAL world, your attempt "might" work....if you could sit there all day and match your power use to the output of the panels every given second ( or maybe split second )....but I know I sure don't have time to do that......so I pull my excess needs ( wife flips on the oven, or the dryer, or a hair dryer, or anyone of a dozen other things ) from the grid, if the grid is up, and from my batteries ( on limited circuits.....she's just flat out of luck with the oven or the dryer....ahahahaaa ) if the grid is down.

Then, when we have excess power the house is NOT using, the meter turns backwards as we put it back on the grid. In off grid situations, if the battery was fully charged, and you weren't using the full power the panels produce, power simply wouldn't BE produced.....the panels just sit there at idle until a load occurs.

That's the WHY of what these other guys are trying to tell you when they say "It won't work"......because it won't work.

[Larc]

The thickness of the soup we call "atmosphere" really does block a lot of power from the sun in the dawn-10am, and 3pm - sunset. The 4 hours around noon[+2,-2], are the productive ones, so an "ultra tracker" won't help much outside those hours.

You don't "bypass" batteries in the daytime, you have to recharge them, and then, use "opportunity" loads in the afternoon, after the batteries have begun the absorb part of the cycle, and you have some spare PV to run the washer and maybe air conditioner.

If you feel you can get by with only small loads at night, great. I won't tell you to spend $ needlessly, but if you discharge batteries too deeply, you shorten their lifetimes.

Sorry, newbie, just getting my 1 post so can view this pdf. great forum!

[TinFury]

This was one of my main questions I wanted to ask before I start buying equipment. And it will be off grid.

With the EXTREMELY high price of batteries now, which from my research, now way surpasses the cost of panels factoring in life of product, it doesn't seem logical to have a large battery bank if the majority of electrical use will be during sunlight. I will still have batteries, but I was thinking something like 2 6v 390Ah batteries for minor use after sundown.

Figuring you sleep 6-8 hours at night and here in Arizona you've got say, at least 9-12 hours of sunlight a day. And I don't understand why people wouldn't put some panels on a "fairly simple" pole mount which can be moved by motor or hand. Wouldn't you then get pretty much the full amount of "sun power" sun up to sun down?

That being said, there must be a way to pretty much bypass the batteries during the day, instead of spending thousands of dollars on batteries. Seems like an awful waste to have to use the batteries as a go between, unless it doesn't affect their life, which leads me to another question. Does it? When you have say 1000 watts of sun power and you use less than that at any given time while the panels are producing that, does the power just kinda pass through the battery without degrading life?

I'm no expert. But I think I understand what your saying. Yes..... it will work. It won't work reliably but yes I've seen people run dc appliance directly off of solar panels.

[billvon]

It fact I cant say enough good things about it. the shunt is always on the mill rather than having a dump load that has to be switched on.

Shunt loads are dump loads. A good shunt regulator will throttle the power through the dump load to control the voltage continuously. More primitive shunt regulators will turn it on and off rapidly to provide a similar effect. But yes, they work well when you have the extra power.

[Roelfiest]

A variation to above matter - different circumstances

Panels don't produce a nice, even steady flow of electricity like a generator does ( heck, even they bog down when you load them up )....a fixed panel produces a little at sunrise, then the most around noon, then tapers off again in the afternoon as the sun angle falls away from perpendicular to the face of the panel. Also, weather conditions GREATLY affect the output. Cloud moves over, output falls WAY off.



In a IDEAL world, your attempt "might" work....if you could sit there all day and match your power use to the output of the panels every given second ( or maybe split second )....but I know I sure don't have time to do that......so I pull my excess needs ( wife flips on the oven, or the dryer, or a hair dryer, or anyone of a dozen other things ) from the grid, if the grid is up, and from my batteries ( on limited circuits.....she's just flat out of luck with the oven or the dryer....ahahahaaa ) if the grid is down.

Then, when we have excess power the house is NOT using, the meter turns backwards as we put it back on the grid. In off grid situations, if the battery was fully charged, and you weren't using the full power the panels produce, power simply wouldn't BE produced.....the panels just sit there at idle until a load occurs.

That's the WHY of what these other guys are trying to tell you when they say "It won't work"......because it won't work.[/QUOTE]
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If I may - my first post. My situation is related to above subject.

I have panel that I want to hook up to a submersible pump without use of a battery. When the sun comes up the pump starts churning. When a cloud passes or the night falls, all goes quiet. Location is in Thailand; there is no rush to get the water pumped up in a short time. Rainy season is six month, dry season is four months. The tank is plenty big. What do I need in between the panel and the pump.

Panel is 136W, Vmax 33V, Voc 46 V, Pmax 4.1 A. Pump 24 VDC, max Amp 4

The pump specs call for the use of a battery; probably, because it is not healthy to run at lower voltage, but it might run ok on 33V,
What would I need to make this work without a battery?
Thanks
Roelf

[inetdog]

I have panel that I want to hook up to a submersible pump without use of a battery. When the sun comes up the pump starts churning. When a cloud passes or the night falls, all goes quiet. Location is in Thailand; there is no rush to get the water pumped up in a short time. Rainy season is six month, dry season is four months. The tank is plenty big. What do I need in between the panel and the pump.

Panel is 136W, Vmax 33V, Voc 46 V, Pmax 4.1 A. Pump 24 VDC, max Amp 4

The pump specs call for the use of a battery; probably, because it is not healthy to run at lower voltage, but it might run ok on 33V,
What would I need to make this work without a battery?
Thanks
Roelf

To get the most out of the available panel power when the sun is shining and to protect your motor at the same time, you need to search for a device called a "linear current booster". Its job is to take the small amount of current that the panels produce during the early and late hours and convert it to a higher current at a lower voltage so that the motor still gets enough energy to do some pumping. And to cut off the feed to the motor completely when the current to the motor gets too high (which is what, along with sitting there not spinning at all but still getting power, would most likely to damage the motor.)

[Roelfiest]

To get the most out of the available panel power when the sun is shining and to protect your motor at the same time, you need to search for a device called a "linear current booster". Its job is to take the small amount of current that the panels produce during the early and late hours and convert it to a higher current at a lower voltage so that the motor still gets enough energy to do some pumping. And to cut off the feed to the motor completely when the current to the motor gets too high (which is what, along with sitting there not spinning at all but still getting power, would most likely to damage the motor.)

Thank you Inetdog. That was a vast reply on my first post.
Now I know that it can be done, I will be reading up on the "linear current booster". I hope I will find all the answers there, and not only more questions to confuse me.
Thanx again?
R.

[ZoNiE]

There is an inverter MFG in Taiwan making a GT inverter that will run w/o Grid power or battery. kinda new, No track record. I'll post if I can find the info. Of course, no output if the panels don't output some minimum that the inverter requires.

They were showing it at Intersolar running a refrigerator and a few other items.

Commercial Flywheel systems are available. There is an Intel Facility in Oregon which has one that keeps things going until the Diesel's fire up. I have not seen it, but it does exist. Perhaps there is someone on the board here who works at Ronler Acres could find out who makes it?

[russ]

There is an inverter MFG in Taiwan making a GT inverter that will run w/o Grid power or battery. kinda new, No track record. I'll post if I can find the info. Of course, no output if the panels don't output some minimum that the inverter requires. Wow not - no big deal until NEC allows it and they are UL or equivalent approved.

They were showing it at Intersolar running a refrigerator and a few other items.

Commercial Flywheel systems are available. There is an Intel Facility in Oregon which has one that keeps things going until the Diesel's fire up. I have not seen it, but it does exist. Perhaps there is someone on the board here who works at Ronler Acres could find out who makes it?

Commercial flywheels - yep there are a few - damn few which says they are not practical for whatever reason

[SunEagle]

Commercial flywheels - yep there are a few - damn few which says they are not practical for whatever reason

I thought so too but I may actually be working on a project concerning a 2500kw flywheel system in Canada. They are having an issue with harmonics generated by the flywheel drives affecting other loads on the same system. Once I learn more about the project and find out what I can talk about I will provide some more details.

[Roelfiest]

To get the most out of the available panel power when the sun is shining and to protect your motor at the same time, you need to search for a device called a "linear current booster". Its job is to take the small amount of current that the panels produce during the early and late hours and convert it to a higher current at a lower voltage so that the motor still gets enough energy to do some pumping. And to cut off the feed to the motor completely when the current to the motor gets too high (which is what, along with sitting there not spinning at all but still getting power, would most likely to damage the motor.)

I found an LCB very easy, on the web, once I knew what to look for. I acquired one from Solar Converter, Inc., made in Canada. The manufacturer was on back order, but I found a supplier who shipped it. Arrived two day, which is in two days. The specs, a 7 Watt unit, is exactly what I needed.
Tomorrow is testing time.
Thanx again for your input.
R.