Solar panel/s to power my shed

Jared88

Hi, sorry newbie here. I have two Calcium 12V car batteries, I would like to run my shed at 240V with max of 4KWh, would anyone please recommend what I need to do this.
Thank you.

Jared.

Ectophile

4kW is some serious power for a couple of 12V batteries.  If you wire them in parallel, it's 333A at 12V.  Wire them in series and it's still 166A ar 24V.  Your batteries won't last very long at those currents.

You'd need the solar panels.  A solar battery charger.  And a big inverter.

Benny2020

He said kwh not kw

victor2

Jared88 said:

Hi, sorry newbie here. I have two Calcium 12V car batteries, I would like to run my shed at 240V with max of 4KWh, would anyone please recommend what I need to do this.
Thank you.

Jared.

Welcome to the forum!

What do you mean by "max of 4KWh"? If you're thinking of being able to power a 4KW device, you'll need more than a couple of old car batteries. Not to mention an (expensive) inverter to deliver that much power, or solar panels to charge substantial batteries.

Define what you want to power.

Just to give you an idea, I have LED lighting and a 6W ceiling fan in my grandchildren's "playhouse". Power comes from an old 12V car battery I replace every year with another I get for nothing from a friendly mechanic I know - they are ones no longer capable of driving a car starter motor. A single solar panel rated at 20W charges the battery through an inexpensive charge controller, which also controls the output. No inverter required as it's all 12V DC powered.

Only gets used for short periods in the summer, with timers on the fan and lights as the little ones forget to switch them off.

Edit- You might find some useful information here: https://forums.moneysavingexpert.com/categories/green-ethical-moneysaving

Jared88

victor2 said:

Jared88 said:

Hi, sorry newbie here. I have two Calcium 12V car batteries, I would like to run my shed at 240V with max of 4KWh, would anyone please recommend what I need to do this.
Thank you.

Jared.

Welcome to the forum!

What do you mean by "max of 4KWh"? If you're thinking of being able to power a 4KW device, you'll need more than a couple of old car batteries. Not to mention an (expensive) inverter to deliver that much power, or solar panels to charge substantial batteries.

Define what you want to power.

Just to give you an idea, I have LED lighting and a 6W ceiling fan in my grandchildren's "playhouse". Power comes from an old 12V car battery I replace every year with another I get for nothing from a friendly mechanic I know - they are ones no longer capable of driving a car starter motor. A single solar panel rated at 20W charges the battery through an inexpensive charge controller, which also controls the output. No inverter required as it's all 12V DC powered.

Only gets used for short periods in the summer, with timers on the fan and lights as the little ones forget to switch them off.

Edit- You might find some useful information here: https://forums.moneysavingexpert.com/categories/green-ethical-moneysaving

Thanks Victor, sorry about the confusion, will post again when I have a better understanding.

Gerry1

Whether it's 4kW of instantaneous power (think of it like the power of a water cannon) or 4kWh of stored energy (think of it like the size of an Olympic swimming pool), you'll have big problems.

As @Ectophile notes, 4kW power from 24V needs 166A so they would have to be batteries in good condition, especially when it's cold.  Think of it like trying to use the starter motor to move a car that's out of petrol: you wouldn't get very far.

Even if you had a massive and expensive inverter, the battery wouldn't last long.  You'll be lucky if each battery stores 100AH (100 amp hours), so that's a total of 2400Wh (2.4kWh) of stored energy, with a theortical run time of 100/166 hours (36 minutes) but that's ignoring conversion losses.  The batteries also won't like being flattened or used at high current for long.

Basically you'd need a Powerwall costing £thousands.  Cheaper to run a cable !

QrizB

Jared88 said:

Hi, sorry newbie here. I have two Calcium 12V car batteries, I would like to run my shed at 240V with max of 4KWh, would anyone please recommend what I need to do this.

Welcome to the forum.

You do need to do a bit more reading so you understand exactly whay you're doing and how it works. There are some good videos on this YouTube channel (which belongs to Will Prowse, who is US-based so some of the specifics are different but the general idea is the same):

https://www.youtube.com/channel/UCoj6RxIAQq8kmJme-5dnN0Q

Once you understand what you are doing, there are various suppliers of kits. Here's an example:
https://www.bimblesolar.com/offgrid/complete-packages

Or you can buy individual components if you'd prefer.