Would this work?

[Greenfield]

Hi guys I’m trying to make a battery system that is really simple and am asking to see if this would work.

all i want is to bring down my power bill and cover power over peak times (I don’t use much power)

i have a 4.2 kw solar system on my roof

heres the plan

power point
timer
smart 24v battery charger
2x2 12v batteries
low voltage cut off
inverter
timer
power point

so the theory is, at 9am smart charger turns on and charges at 300w until about 5 but the smart charger runs off when batteries are full.

batteries will be in parallel and sync 2x2 to get 24v and still have a good amount of current. I’m aiming for 2 kw of usable power.

At 6pm my last PowerPoint turns on and feeds into my house at a constant rate until the low voltage cut off turns it off. (I’m aiming for 4 hours but if I can get 300w inverter that world be perfect as it can last for longer)

This feeds into the PowerPoint so it should only reduce what I’m taking from the grid. this is the part I’m asking advice on. Would this work? Feeding into the Powerpoint?

[Ampster]

What is a PowerPoint? To offset house loads you will need a Hybrid Grid Tie inverter. It is unlikely you will find a 300 Watt version.

[SunEagle]

I am a little confused what you are building concerning the Power Point.

Also based on all data I have seen a Pb battery system will usually cost a lot more to generate a kWh then purchasing it from your POCO. Even if you are trying to limit the grid usage because of high rates during "peak" times a Pb battery system can cost more than $0.50/kWh it can generate while most POCO's may charge at worst about $0.30/kWh

[qrper]

Gosh love your thinking but I feel it way off the mark. As others have commented on, it's going to cost you more to buy the batteries than simply pay for the power.

I think you'd be better off taking the $$$ and using it to buy LED lighting, Energy Star appliances, and other energy saving devices.

I don't have a clue what power point is other than a software suite that microsoft sells.

I have to ask, did you recently purchase the 4.2kW panels or where they already installed? Where they connected to the gird or battery backup?

And?? Why run a smart charger if you have solar panels on the roof?

[Greenfield]

What is a PowerPoint? To offset house loads you will need a Hybrid Grid Tie inverter. It is unlikely you will find a 300 Watt version.

I can’t just get a solar 1 kw inverter than put a current limiter on it? A power point is a thing on the wall I plug my tv and stuff into into (I don’t know what other countries call it).

[Greenfield]

Gosh love your thinking but I feel it way off the mark. As others have commented on, it's going to cost you more to buy the batteries than simply pay for the power.

I think you'd be better off taking the $$$ and using it to buy LED lighting, Energy Star appliances, and other energy saving devices.

I don't have a clue what power point is other than a software suite that microsoft sells.

I have to ask, did you recently purchase the 4.2kW panels or where they already installed? Where they connected to the gird or battery backup?

And?? Why run a smart charger if you have solar panels on the roof?

I was going to us deep cycle 12v led batteries. I need charge to cut off when they are full it’s not good to keep these batteries charging when they do not need it.

The 4.2 kw system is tied into the grid

as for cost of power, I generate more power than I need during the day. I plan on using the extra power to charge the batteries (under my calculations I can do this and still make about $1 per day). I understand it will charge at a constant rate until full but I’m confident I’ll still generate more than the charging takes.

im in Australia and we call a power socket a power point (a thing I plug all my appliances into)

as for led lighing and decreasing usage this is done. I use about 400w per hour when I’m not home and 1.5kw when I am.

if this would work I could put it together for $3-400 because second hand 12v deep cycle batteries don’t cost much and I already have a battery charger.

[Greenfield]

I am a little confused what you are building concerning the Power Point.

Also based on all data I have seen a Pb battery system will usually cost a lot more to generate a kWh then purchasing it from your POCO. Even if you are trying to limit the grid usage because of high rates during "peak" times a Pb battery system can cost more than $0.50/kWh it can generate while most POCO's may charge at worst about $0.30/kWh

Can I connect a caravan style solar/wind inverter into a power point (socket?)

the bateries will be charged while my solar system is running so I wouldn’t be paying for the charge? If I understand things right the simply take my solar generated and minus the amount of energy I have used and I rather pay or gain the difference.

the problem is my feed in Tarif is 0.12 yet I buy it for 0.30ish.

[Greenfield]

This is the inverter I was looking at

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com.au%2Fulk%2Fitm%2F123227657716

[Ampster]

This is the inverter I was looking at
.

It may say it is a Grid Tie inverter but, for that price, does it have the required interconnect circuitry to comply with your local building authority?

[Mike90250]

.... A power point is a thing on the wall I plug my tv and stuff into into (I don’t know what other countries call it).

That's commonly referred to as a Wall Outlet .

A little transformer for charging your phone is a Wall Wart, in the middle of a cable for your computer, it's a Power Brick.

In the USA, any Plug-In Inverters ( that you plug into a wall outlet) are not code approved because of several wiring issues that can over load the wire in the wall and never trip the breaker panel.

[SunEagle]

Can I connect a caravan style solar/wind inverter into a power point (socket?)

the bateries will be charged while my solar system is running so I wouldn’t be paying for the charge? If I understand things right the simply take my solar generated and minus the amount of energy I have used and I rather pay or gain the difference.

the problem is my feed in Tarif is 0.12 yet I buy it for 0.30ish.

If you look at the number of cycles in the battery life and the % of discharge you can calculate the kWh they can provide. Then divide that lifetime kWh value into the cost of the batteries. My guess is that even with used batteries (by the way much less cycles then a new set) the calculation will come to over $0.50/kWh. How is that saving you money?

[Greenfield]

That's commonly referred to as a Wall Outlet .

A little transformer for charging your phone is a Wall Wart, in the middle of a cable for your computer, it's a Power Brick.

In the USA, any Plug-In Inverters ( that you plug into a wall outlet) are not code approved because of several wiring issues that can over load the wire in the wall and never trip the breaker panel.

Wall outlet thanks for the information. In Australia we call it a power point.

If i put a breaker between the inverter and the wall outlet would this fix the loading problem (i do see how that could be dangerous).

and if it does i see it would still be illegal... Is there a way i can make this safe and legal?

[jflorey2]

This is the inverter I was looking at

Might work; those sorts of inverters have a very iffy track record. You will likely need a better one, with whatever ratings your country requires.

Can I connect a caravan style solar/wind inverter into a power point (socket?)

No. You need a grid tie inverter, not a "caravan style" inverter. And in most places it has to be hardwired. Simple way to tell if a grid tie inverter is intended for legal installations - it doesn't have a plug.

the bateries will be charged while my solar system is running so I wouldn’t be paying for the charge?

Right. But you will be paying for the BATTERIES. Even if you treat them well (unlikely) they will only last about two years. How much do you pay in power a year, and how much will a new set of batteries cost every two years?

If I understand things right the simply take my solar generated and minus the amount of energy I have used and I rather pay or gain the difference.

the problem is my feed in Tarif is 0.12 yet I buy it for 0.30ish.

If you generate power during the day AND that's when you are running all your heavy loads, then you are running them for free. (In other words, you are avoiding paying the .30 per kwhr for the energy you generate, even if you are not generating enough to feed back.)

[jflorey2]

If i put a breaker between the inverter and the wall outlet would this fix the loading problem

No, it's not a problem at that outlet, it's a problem in the wall wiring.

and if it does i see it would still be illegal... Is there a way i can make this safe and legal?

Sure. Call up a local installer and ask him for a quote.

[Greenfield]

If you look at the number of cycles in the battery life and the % of discharge you can calculate the kWh they can provide. Then divide that lifetime kWh value into the cost of the batteries. My guess is that even with used batteries (by the way much less cycles then a new set) the calculation will come to over $0.50/kWh. How is that saving you money?

Mine come it at $0.18

however it looks like it might be illegal so i might give it a miss