Solar panels for power tool charging?

[hotponyshoes]

I'm not in a position to fit solar panels to the roof of the houseor fit a ground array but I'm wondering if anybody has fitted a small scale jib for anything useful?

I have a couple of m2 of shed roof that gets good sunlight which is never going to run a washing machine but I thought it might be possible to put it into use for something?

I'm used to fitting panels to horseboxes/campers but that's generally just to charge up leisure batteries to run 12v equipment.

Although I do have a few low voltage devices in my house that I could potentially run for free I got thinking that a better use for the power stored in batteries might be to use the batteries themselves.
I generally use about 10-12a/h worth of cordless tool power a day so those batteries would be ideal to sit there getting charged up for free but the majority of them are 18v so I'm not sure how feasible it is to set up solar to charge them?

I'm thinking a couple of panels, charge controller to a 12v car battery, small inverter feeding a socket rail with the original battery chargers plugged into that.

But that seems like a lot of components in the system to introduce losses.
Plus if I stick 6 batteries in at once the small inverter is probably going to shut down.

If the chargers can take a 110v input would a 110v inverter be more efficient than a 230v?

I've seen some car chargers that take 12v and charge a 18v battery but they are expensive and I already have loads of normal ones.

Could I get a charge controller for the panels to directly charge 18v li-ion packs (without setting the shed on fire?

I must admit, I have no idea how much it actually costs me to recharge a tool battery form the mains so maybe I should work that out first as the savings may be negligible?

What about other small scale use?
Is anybody just fitting a couple of panels in parallel and running the wires directly to a 12v immersion element in the hot water tank for example?
That seems like all you would need is a thermal cutout on the tank to disconnect the power if it got too hot and your up, running and saving money for a hundred quid or so.
I know it's not going to do much in the winter when you really want the hot water but, over the last bit of hot weather 40c showers have been suiting me nicely and a few months a year of that for free might be worth saving?

 

[James1979]

I have one of those ring ones that’s about the size of an a4 bit of paper on each of the bikes to keep them topped up.

Might be food for thought? Obviously 12v out, so potentially could be taken to a charger via a battery and inverter.

You can get 12v chargers for most brands now that run off a vehicle so that would lose the inverter and just have the battery as an accumulator?

 

[gaz1]

just do a proper setup

4 panels

upgraded system

 

[123hotchef]

iterestingI shall watch those videos later myself I was thining about a solar pannel for the wifes pick up for where we are camping, to keep the lesuire batteries toped up and running the fridge and lighting.

 

[J1nx]

I have a little station in a shed (ex site office). Two panels on roof, into a charge controller, some random large lead-acids and Makita 12v chargers.
As for cost, it’s now probably 7p a charge at new price cap, will take a while to pay back but convenient for me.

Excuse the spider web cabling

 

[outofthefire]

I'm not in a position to fit solar panels to the roof of the houseor fit a ground array but I'm wondering if anybody has fitted a small scale jib for anything useful?

I have a couple of m2 of shed roof that gets good sunlight which is never going to run a washing machine but I thought it might be possible to put it into use for something?

My boss has just bought 6 solar panels and all the rest of the gubbins to stick on his shed roof, i'm sure he said it would supply 4kw, that should more than charge your tools He reckons it'll pay for itself in a year if fuel bills go up as expected.

 

[James1979]

My boss has just bought 6 solar panels and all the rest of the gubbins to stick on his shed roof, i'm sure he said it would supply 4kw, that should more than charge your tools He reckons it'll pay for itself in a year if fuel bills go up as expected.

We are between camper vans. When I stripped the last one pre selling off the carcass, I kept all the panels etc etc.

They’re now on workshop roof with the controller inside. Just need a couple of batteries and they will run low level stuff like lights etc. also using them saves them waiting around to get broken.

We want to do a new build but council are being cnuts. Hoping this will demo to them that I can do this on a single dwelling scale. In a few years there will be a glut of EV batteries but only bad in one cell.

Reckon a couple of teslas worth will run our household needs. Even the washing machine - we had a special one in the camper off an inverter. Only thing we didn’t have was a big f-off fridge or a tumbler. That was a deal breaker in Norway in winter, unfortunately

 

[barracuda816]

Depending on how long you need between solar for me a Tesla bank would be over kill. We use 5kwh per day that’s whilst being frivolous. So a 70kwh battery would last ages. My problem is we have 3phase in the house so would need 3 inverters tied. That is out of my budget at the Moment.

 

[James1979]

3phase is a problem I would love to have!!

Especially in the house. I could get Mrs79 an industrial washing machine

 

[barracuda816]

3phase in the house is fairly common here. They call it Strong power (stark strom). But we are limited at the moment to 50a per phase.

 

[Barking Mat]

Instead of buying solar panels, voltage regulators and batteries...

Couldn't you just charge your batteries in the house ?

Panels, regulators and batteries all need changing every 5 - 10 years.

Not being facetious, but investment ?

Unless you live off grid ?

 

[hotponyshoes]

Instead of buying solar panels, voltage regulators and batteries...

Couldn't you just charge your batteries in the house ?

Panels, regulators and batteries all need changing every 5 - 10 years.

Not being facetious, but investment ?

Unless you live off grid ?

I charge them in the house at the moment

It's only because I was looking at the sunny spot on the shed roof and thought 'ooohhh, I could get some free electricity from that'

But, like you say, with the cost of the investment for the bits and the ongoing replacement it might work out cheaper just to use the mains sockets!

 

[bert]

I've just fitted a 170w panel and controller on my boat. In direct sunlight all day the panel provides 450 to 500wh of power which I think is about 26amps

Enough to run all the 12v on the boat and came in at under £300

 

[Gareth J]

I'm not in a position to fit solar panels to the roof of the houseor fit a ground array but I'm wondering if anybody has fitted a small scale jib for anything useful?

I have a couple of m2 of shed roof that gets good sunlight which is never going to run a washing machine but I thought it might be possible to put it into use for something?

I'm used to fitting panels to horseboxes/campers but that's generally just to charge up leisure batteries to run 12v equipment.

Although I do have a few low voltage devices in my house that I could potentially run for free I got thinking that a better use for the power stored in batteries might be to use the batteries themselves.
I generally use about 10-12a/h worth of cordless tool power a day so those batteries would be ideal to sit there getting charged up for free but the majority of them are 18v so I'm not sure how feasible it is to set up solar to charge them?

I'm thinking a couple of panels, charge controller to a 12v car battery, small inverter feeding a socket rail with the original battery chargers plugged into that.

But that seems like a lot of components in the system to introduce losses.
Plus if I stick 6 batteries in at once the small inverter is probably going to shut down.

If the chargers can take a 110v input would a 110v inverter be more efficient than a 230v?

I've seen some car chargers that take 12v and charge a 18v battery but they are expensive and I already have loads of normal ones.

Could I get a charge controller for the panels to directly charge 18v li-ion packs (without setting the shed on fire?

I must admit, I have no idea how much it actually costs me to recharge a tool battery form the mains so maybe I should work that out first as the savings may be negligible?

What about other small scale use?
Is anybody just fitting a couple of panels in parallel and running the wires directly to a 12v immersion element in the hot water tank for example?
That seems like all you would need is a thermal cutout on the tank to disconnect the power if it got too hot and your up, running and saving money for a hundred quid or so.
I know it's not going to do much in the winter when you really want the hot water but, over the last bit of hot weather 40c showers have been suiting me nicely and a few months a year of that for free might be worth saving?

Do you have mains power to the shed? If so, is the cable rating above the amount of power the panels could potentially produce? If so, why not just install a miniature 240v AC array? It'll potentially be more expensive than keeping everything DC, but the added advantage is that it'll contribute towards everything you plug in and, being such a small array, will be easier to use the generation

 

[hotponyshoes]

I've just fitted a 170w panel and controller on my boat. In direct sunlight all day the panel provides 450 to 500wh of power which I think is about 26amps

Enough to run all the 12v on the boat and came in at under £300

I've done the same on my boat, not sure what they produce but it's certainly more then enough to keep the batteries topped up year round and run the radio/sonar during the summer days which is the only time we actually use it.

I've fitted plenty of systems like this but only ever on mobile stuff where it charges a 12v battery.
This is why I was thinking I could mount something similar on the shed roof and charge up a couple of batteries but, I don't really have anything I need to connect to batteries in the shed so then I thought it would make more sense to charge the power tool batteries directly.

Do you have mains power to the shed? If so, is the cable rating above the amount of power the panels could potentially produce? If so, why not just install a miniature 240v AC array? It'll potentially be more expensive than keeping everything DC, but the added advantage is that it'll contribute towards everything you plug in and, being such a small array, will be easier to use the generation

Interesting point, I do have power but this is a garden type shed not a workshop, there is a 16a feed coming from the consumer unit in the house.
I have 2 fridges and 2 freezers in my house that are about the only things running during the day, these will be using more power when the weather is hot (so at the times the panels should be producing the most) and it would be interesting if I could feed enough back in to offset what they use.

So, in theory, would I basically connect the panels to an inverter in the shed and connect that to the mains?
I guess the inverter needs to sync to the frequency of the incoming mains?
Then, if my freezers are using 1000w and my panels manage to produce 1000w then my electric meter should stop turning?

 

[bert]

You can't just add solar power into the house as it needs to isolate in a power cut. You will also need a newer smart meter incase you feed back into the grid

 

[hotponyshoes]

You can't just add solar power into the house as it needs to isolate in a power cut. You will also need a newer smart meter incase you feed back into the grid

Could I (forgetting about rules/regulations) run the shed cable through a contactor and power the coil of the contactor via the incoming mains?

 

[J1nx]

The inverter takes care of that, it won’t generate on mains failure. You can of course add back-feed protection with a contactor but not required.
I agree a mains tie is better, see my thread on here, just need to do a DNO notification but I had no issues.

 

[pressbrake1]

iterestingI shall watch those videos later myself I was thining about a solar pannel for the wifes pick up for where we are camping, to keep the lesuire batteries toped up and running the fridge and lighting.

There’s a debt of a small country there, victron is expensive!
Invest in as many batteries as possible and think of your shed roof as theoretically 200w per square metre

 

[Gareth J]

So, in theory, would I basically connect the panels to an inverter in the shed and connect that to the mains?
I guess the inverter needs to sync to the frequency of the incoming mains?
Then, if my freezers are using 1000w and my panels manage to produce 1000w then my electric meter should stop turning?

Exactly like that. Don't worry about what the inverter is doing, it'll just sort it out.