can i use a solar panel without using battery

[billvon]

I wanted to use an Outback or Xantrex 48 volt inverter-charger tied to the grid and have a small battery bank for "load smoothing" but I agree the high current and cycling would destroy the batteries in short order.

So use UPS batteries and don't cycle them unless there is an outage.

I thought about using the inverter as a straight grid-tie unit and reconfiguring it with batteries and charge controller only if the power was down for several days. Both Outback and Xantrex manuals are pretty adamant that they cannot be used without a battery bank.

Correct. You could go with an ultracapacitor bank; they last for decades and have VERY low ESR, allowing high peak powers from small amounts of energy storage. But you are going to spend a lot more for an ultracap bank than for a lead-acid bank.

I may use a grid-tie Sunny Boy 6000 with my panel strings in series to deliver 300 volt DC to the inverter and have the capability to re-configure for 60 volt DC to feed a separate Aims 7000 watt 48volt inverter.

You'd still need a battery. The impedance of even huge arrays isn't low enough to start large loads.

Contrary to some things that have been said on this thread, you can run some loads off the PV's without a battery.

Absolutely; you can run anything that can run on DC over the range that the panels will produce, and that has a higher minimum impedance than the PV array does.

There are also some other problems such as the inverter input voltage being exceeded when there is no load, but I think that could be solved with a simple circuit and a "shunt" or bypass load resistor. I could even use a water heater as the bypass load. Hot water equals happy wife.

Be very careful with this. I've blown inverters trying to do the same thing. The problem is that without storage your diverter load controller has to be very fast; faster than anything on the market right now. You'd need a closed loop high frequency PWM controller that accurately regulates voltage, and they are not trivial to build.

I saw a system in Northern Africa that used a huge flywheel instead of batteries to supply backup power for 60 seconds while the backup generator fired up and stabilized. I just might build one of those instead of spending 5k on batteries.

Warning. Flywheel containment problem = unhappy wife. Releasing all that energy at once will not be a good thing whether the storage is via battery or flywheel.

Think outside the box a little.

Ultracaps. As an example, 10 BMOD0058's from Maxwell will give you about 200 watt-hours of energy storage at something like 30kW max power output. Cost you around $1500. Warning - you will be quite far into experimental territory with this, and thus any such experiments should be kept well separate from wives who do not enjoy large thermal or rapid disassembly events.

[duncangalt]

Why I to want to use a load without a battery

It's been thirty plus years since my electrical engineering classes, so I don't pretend to be an expert on this. I am planning on installing a 6 kw grid tie system without battery backup. I live in Southern California so the specter of several days without power haunts me. I have a multi fuel backup generator and enough gas for a week, and propane for a few days and natural gas for as long is it comes out of the meter. BUT what do I do after that? I have the potential for 6000 watts of solar power at high noon that I could use to cool my freezer but I cannot use it because my inverter shuts off when doesn't see a sine wave from the utility. I could install a battery backup with associated charger, charge controller etc and spend a considerable amount of time and money maintaining and replacing batteries that I don't need or use for years on end waiting for the big quake. I was in the satellite transmission industry for many years. I was around 100 kw UPS systems with huge battery banks. They scare the stuffing out of me.

I wanted to use an Outback or Xantrex 48 volt inverter-charger tied to the grid and have a small battery bank for "load smoothing" but I agree the high current and cycling would destroy the batteries in short order. I thought about using the inverter as a straight grid-tie unit and reconfiguring it with batteries and charge controller only if the power was down for several days. Both Outback and Xantrex manuals are pretty adamant that they cannot be used without a battery bank.

I may use a grid-tie Sunny Boy 6000 with my panel strings in series to deliver 300 volt DC to the inverter and have the capability to re-configure for 60 volt DC to feed a separate Aims 7000 watt 48volt inverter. I could plug it in at mid day and run some loads, but I doubt it would have the capacity to start the freezer compressor. Contrary to some things that have been said on this thread, you can run some loads off the PV's without a battery. Obviously the lower the load as a percentage of the PV array capacity and the more linear the load the better, let's say 1.5 kw on a 6 kw system. Cloud goes over, voltage drops below inverter minimum and switches off, better than nothing. There are also some other problems such as the inverter input voltage being exceeded when there is no load, but I think that could be solved with a simple circuit and a "shunt" or bypass load resistor. I could even use a water heater as the bypass load. Hot water equals happy wife.

I saw a system in Northern Africa that used a huge flywheel instead of batteries to supply backup power for 60 seconds while the backup generator fired up and stabilized. I just might build one of those instead of spending 5k on batteries. No power at night but my beer will be cold and my wife will be showered and happy.

Think outside the box a little.

[noone]

PS: I got one of those "eternal" moving magnet generator flashlights about 15 years ago, and the capacitor died about five years ago. It still makes lots of light, but just in pulses as I shake it. <sigh>

You can get one that you wind up instead of shake now....maybe when the cap dies it would still be ok in a pinch.


I think that powering SOME things without a battery from solar will be the norm in years ahead.

Only things that require power for short periods and that do not have voltage sensitive electronics but for resistive loads will be good....and especially if a panel is made to fit a load (or particular common power requirement).

Works for me for somethings at least.

[inetdog]

You forgot one Sunking - Scams - what was that company who would turn the world on it's ear using supercaps for EVs? Disappeared after they collected all the money they could and never even gave a sniff of a product.

The other large application for supercaps (regardless of why they were first developed) is for very-low-power maintenance needs for electronics that get external power intermittently but dependably and have to ride through the time in between. A properly designed supercap will have a longer shelf and service life than just about any chemical battery system, and *can* (not necessarily all will) tolerate higher temperature extremes.

But that does not make them suitable for storage of larger amounts of energy for long term needs. Batteries still own that market.

PS: I got one of those "eternal" moving magnet generator flashlights about 15 years ago, and the capacitor died about five years ago. It still makes lots of light, but just in pulses as I shake it. <sigh>

[Sunking]

You forgot one Sunking - Scams - what was that company who would turn the world on it's ear using supercaps for EVs? .

That was EESTOR. They even caused a Canadian EV manufacture called Zenn Motors to go bankrupt waiting for the product to be released. Ironically Lockheed Martin reportable bought all rights for energy weapons use for $10 million share of the company.

[russ]

Beright there is nothing about Supercaps that make them slow to charge. They charge and discharge just as fast as any capacitor. You can charge then in a microsecond if the source is capable of supplying the charged. All caps charge in 5 Time Constants, and TC = Resistance x Capacitance. The time element is dictated by the amount resistance and capacitance in the circuit.

Supercaps were developed for two primary applications; Energy weapons and regenerative braking in electric vehicles.

You forgot one Sunking - Scams - what was that company who would turn the world on it's ear using supercaps for EVs? Disappeared after they collected all the money they could and never even gave a sniff of a product.

[Sunking]

In using ultracaps - i find just the opposite of what one might think (different technology)-discharge is slow.

The challenges: slow to charge and dc to ac converters cut out close to 10V. So, yes one needs to keep lots of Amps coming in to keep them charged. The 2600F ultra cap I am using is really small and light(compared to caps of the past)__ lots of folks doing work to shorten charge time.

Beright there is nothing about Supercaps that make them slow to charge. They charge and discharge just as fast as any capacitor. You can charge then in a microsecond if the source is capable of supplying the charged. All caps charge in 5 Time Constants, and TC = Resistance x Capacitance. The time element is dictated by the amount resistance and capacitance in the circuit.

Supercaps were developed for two primary applications; Energy weapons and regenerative braking in electric vehicles.

[Sunking]

I plan to keep playing and designing circuits around them for the ultimate advantage of never having to worry about number of charge cycles-they sound last a long time. I have found however that i do have to address balance of charge when connecting in series and parallel.

Well you might want to do some homework on capacitors. When you connect 2 two of them in series of equal value, you cut the capacitance in half. For example 2-1000 ufd in series = 500 ufd. You are shooting yourself in the foot.

[BeRight]

Apologies

My apologies to all for my diversions and discussing some of my strange/stupid hobbies on this forum.

[russ]

checkout you tube: just type in ultra caps- one video shows the power of one ultra cap 2600F the guy is holding the leads attached to each end of the cap and basically is doing arc welding with it.

I agree: extreme care must be taken when working with high energy devices which includes batteries!

Readers should not confuse ultra capacitors with batteries nor the dangers of either.

The ultra cap energy storage for common household use thingy is one of the current loony green items - going to save the world etc - which is all a bunch of BS

Charged batteries should always be treated with caution and respect.

[BeRight]

youtube video on ultracaps

checkout you tube: just type in ultra caps- one video shows the power of one ultra cap 2600F the guy is holding the leads attached to each end of the cap and basically is doing arc welding with it.

I agree: extreme care must be taken when working with high energy devices which includes batteries!

[russ]

Just brainstorming here_so go easy_issue is storing energy for a short period of time since he seems to want to only power things while he can get solar energy_capacitors can store energy for a little while.

Just as a hobby interest:
Probably not scaleable: i took a fairly large (free) cap bank used in place of batteries and use it to power my regular ac lights in my mostly underground basement while working during the day.

Solar panel to MMPT charger/controller to cap bank to dc to ac inverter to outside inlet plug into basement.

Not recommending this to anyone-please do not do this at home- just keeping the discussion going to maybe explore other non-battery ways to use the sun's energy.

Not only not recommended for others but a bit dangerous for most anyone -

[BeRight]

ultracap

In using ultracaps - i find just the opposite of what one might think (different technology)-discharge is slow.

The challenges: slow to charge and dc to ac converters cut out close to 10V. So, yes one needs to keep lots of Amps coming in to keep them charged. The 2600F ultra cap I am using is really small and light(compared to caps of the past)__ lots of folks doing work to shorten charge time. Their usefulness for real time use of solar power might not be very far away.

In my early stages of playing with these I hooked up eight, charged - connected cheap dc to ac inverter and powered my 42" LCD, and watched TV for 7 minutes. And of course I am having very good results in using ac CFL lighting.

I plan to keep playing and designing circuits around them for the ultimate advantage of never having to worry about number of charge cycles-they sound last a long time. I have found however that i do have to address balance of charge when connecting in series and parallel.

Just my $.02

[Sunking]

Just brainstorming here_so go easy_issue is storing energy for a short period of time since he seems to want to only power things while he can get solar energy_capacitors can store energy for a little while.

Well you bring up a valid point that demands an explanation.

Batteries and capacitors are very similar devices but work and behave quite differently.

• Batteries use chemical energy to store energy, and a capacitor stores it in a electrostatic field just like static electricity.
• Battery terminal voltage is very constant and stable while being charged and discharged. Capacitors voltage varies constantly from 0 volts at 0 charge to its specified terminal voltage. For example lets say you charge a capacitor up to 12 volts. When you discharge it 25% the voltage falls to 6 volts, and at 50% falls to 3 volts.
• A battery take time to charge and discharge, a capacitor can be fully charged in less than a second and discharged just as fast.
• A battery can hold a charge for a very long time, a capacitor cannot.
• But now here is the kicker. A battery can store a massive amounts of energy for a given volume compared to a capacitor. So those caps you say that provide energy can only do so for second or two depending on the size and rate of discharge.

[BeRight]

Big arse capacitor

Just brainstorming here_so go easy_issue is storing energy for a short period of time since he seems to want to only power things while he can get solar energy_capacitors can store energy for a little while.

Just as a hobby interest:
Probably not scaleable: i took a fairly large (free) cap bank used in place of batteries and use it to power my regular ac lights in my mostly underground basement while working during the day.

Solar panel to MMPT charger/controller to cap bank to dc to ac inverter to outside inlet plug into basement.

Not recommending this to anyone-please do not do this at home- just keeping the discussion going to maybe explore other non-battery ways to use the sun's energy.