Capacitor in place of batteries?

[muttonpig]

Hi All, I live on a lifestyle block in Waikato, New Zealand and are on a big push at the moment to reduce my household expenses. I am an Engineer by trade and would rather give something a go for myself than pay someone else to do it. I have recently put together my own 3kw solar system. I wired up 3kw's of 24v panels to 48v to reduce the amount & size of cable used. I have a 5kw grid tie inverter which has an input voltage range of 28v dc to 52v dc and an open circuit voltage of about 80-90v dc, but overlooked the need for a solar regulator/controller. My question is, can I use a large capacitor in place of 48v batteries as I do not want and cannot afford to spend anymore on storage or batteries, I just want to trick the controller to think that batteries are connected. I have sourced a couple of very large capacitors that were removed in good working order from the power factor correction board in the factory I work. I fully understand how quickly capacitors charge & discharge. All I wish to do is power my grid tie inverter. Any help would be much appreciated. Cheers

[inetdog]

Hi All, I live on a lifestyle block in Waikato, New Zealand and are on a big push at the moment to reduce my household expenses. I am an Engineer by trade and would rather give something a go for myself than pay someone else to do it. I have recently put together my own 3kw solar system. I wired up 3kw's of 24v panels to 48v to reduce the amount & size of cable used. I have a 5kw grid tie inverter which has an input voltage range of 28v dc to 52v dc and an open circuit voltage of about 80-90v dc, but overlooked the need for a solar regulator/controller. My question is, can I use a large capacitor in place of 48v batteries as I do not want and cannot afford to spend anymore on storage or batteries, I just want to trick the controller to think that batteries are connected. I have sourced a couple of very large capacitors that were removed in good working order from the power factor correction board in the factory I work. I fully understand how quickly capacitors charge & discharge. All I wish to do is power my grid tie inverter. Any help would be much appreciated. Cheers

Grid tie inverters do not need or use batteries. They are designed to take any and all power coming from the panels and transfer it to the power grid, either for local use or for selling back to POCO, depending on the amount of load you are feeding at the same time.

Batteries are used for an off-grid inverter or for a hybrid inverter. Either of those types require more energy storage than a capacitor could provide. The batteries are needed because the solar panels will be providing a constant output over a short time while your loads may vary. The grid performs the same function of energy storage for a grid tied inverter that batteries do for an off-grid inverter.

[Mike90250]

2 different critters here.

As an engineer, you should realize, that the moment you pull power from a capacitor, it's voltage starts to drop. An inverter will only tolerate a small amount of drop, before it thinks the batteries are dead, and will shut off. Batteries supply a lot of power, and only in the later part of discharge, does their voltage sag appreciably. That's why caps alone, won't work. Even multi-Farad caps, the power/voltage curve just crashes, you can only get a couple % of their power out.

plain Grid-Tie installs, don't use batteries at all.

[Sunking]

PF capacitors are very small in value, and high voltage which means they are completely useless for any low voltage DC filtering and storage. Besides a string Grid Tied Inverter does not use batteries and operates at a DC voltage of 300 to 500 volts. What did you do get a Hybrid inverter or a plug-n-play

[inetdog]

PF capacitors are very small in value, and high voltage which means they are completely useless for any low voltage DC filtering and storage.

All you need is a DC to DC transformer to match the voltage levels properly.
Of course if you have invented a low loss passive bi-directional DC-to-DC convertor, you would not be fooling around with using it in a PV system.

[muttonpig]

What I am concerned about is that the higher voltage from my panels may damage the inverter as it only has an input voltage range of 28-52v dc and the open circuit voltage in full sun is almost 90v. A couple of days ago I connected the dc side to the inverter before dawn and kept an eye on the dc voltage as the sun came up. When the voltage started to reach the minimum input value, the inverter started generating and dropping the input voltage below the min level and the inverter would stop generating. This continued for a while (voltage up & down, up & down) as I would expect (load, unload). But as soon as there was direct sunlight on the panels, the dc voltage shot up to about 80v and stayed there as thou there was no load? all lights were green on the inverter but there was no output. I quickly shut it down to hopefully prevent any damage. This is why I thought I might need to put in a regulator to get a steady 48 volts into the inverter.

[muttonpig]

The grid tie inverter I purchased was a Powerjack PSWGT5000-28-52-220.

[Sunking]

The grid tie inverter I purchased was a Powerjack PSWGT5000-28-52-220.

Afraid you got exactly what you paid for. A Chi-Com POS. Their Advertising is a good clue it is a con job.

A. SURGE PROTECTOR:
sometimes, if you are using some heaving appliance like motor, enginee, cause the voltage up down very fast,in this moment, big amp will come into the grid inverter, easy to cause the ac mos burned, so surge protector will cut down by itself to protect the grid inverter.


B. lightning protection:
you may have experience, when meet the big lightning, the power source of the home appliance may damage,same reason, will also cause the inverter damage, in this moment the lightining protection can release thousand voltage to protect the inverter not damage.


C. HIGH SPEED AC FUSE:
now we put ac fuse outside, each inverter will come our special ac fuse, this will be broken1mini/sec, to make sure high voltage spike come in!

[Mike90250]

The grid tie inverter I purchased was a Powerjack PSWGT5000-28-52-220.

DO NOT use a battery with it. It's meant to run directly off PV panels with specs that match what the booklet calls for.

But since it's a Powerjack, it will likely just take your $ and stop working when it gets hot.

[SunEagle]

Afraid you got exactly what you paid for. A Chi-Com POS. Their Advertising is a good clue it is a con job.

A. SURGE PROTECTOR:
sometimes, if you are using some heaving appliance like motor, enginee, cause the voltage up down very fast,in this moment, big amp will come into the grid inverter, easy to cause the ac mos burned, so surge protector will cut down by itself to protect the grid inverter.


B. lightning protection:
you may have experience, when meet the big lightning, the power source of the home appliance may damage,same reason, will also cause the inverter damage, in this moment the lightining protection can release thousand voltage to protect the inverter not damage.


C. HIGH SPEED AC FUSE:
now we put ac fuse outside, each inverter will come our special ac fuse, this will be broken1mini/sec, to make sure high voltage spike come in!

You are probably right on it being a piece of merde. Or just very bad English translation.

You ought to read most of the manuals that come with the Chinese made RC planes. Don't try to follow them to build your plane or you might have something that fly's backwards.

[bonaire]

There is a blended battery called an UltraBattery from Deka. Manufactured by East Penn Manufacturing. It's both an AGM and UltraCap in one package. Not available to homeowners but it has a possible future for renewable energy storage when the trials work their way through.

[inetdog]

There is a blended battery called an UltraBattery from Deka. Manufactured by East Penn Manufacturing. It's both an AGM and UltraCap in one package. Not available to homeowners but it has a possible future for renewable energy storage when the trials work their way through.

What is the intended application for this? If the object is to have the cap carry the high current surges or pulses to minimize the effects of the battery's internal resistance, then it would be much better to have the ultracap at the load (inverter) end of the connecting wire, since a cap at the battery will do nothing to mitigate the voltage drop across the wire resistance.

[Sunking]

What is the intended application for this?

I am familiar with them. They are PbC batteries where the negative plate is a hybrid carbon lead compound. It allows a standard lead acid battery to to be discharged deeply, very high C rates, and greatly increased cycle life. It has some promise and there are a couple of manufactures just getting started making them most notable Penn'/Deka making a batch of them for a utility scale project. You can learn more here.

Orignally there were developed to compete with Lithium batteries for the EV market, but they will not fly because of the low energy density. However that is not important for RE applications. They cost slightly more than standard Pc, but much less expensive than Lithium. Sandia ran test on Deka, Axiom refused, and initial results were outstanding as Sandia estimates cycle life in excess of 15,000 cycle to 80% DOD. That could be a game changer.

[PNjunction]

I want one!

I wonder if they would just consider removing the capacitor for us RE guys, thereby reducing cost, yet still have the other benefits. Alas, until I see it on store shelves for mere mortals, it will be of the Un-Obtainium variety.

[Sunking]

I want one!

I wonder if they would just consider removing the capacitor for us RE guys, thereby reducing cost, yet still have the other benefits. Alas, until I see it on store shelves for mere mortals, it will be of the Un-Obtainium variety.

No it is the carbon sandwhich which protects the lead plate. Remove that and you have a standard FLA battery.