Solar Power for a Summerhouse

[panthro]

Sorry this has been done to death but I didn't get the answers I wanted from previous threads. Just looking for some help with a summerhouse we're getting build in December (earliest slot they had when I ordered in May!!!).
It's an 8x10ft traditional summerhouse from Skinners, single pane glass and damp membrane on the walls.
https://www.skinners-sheds.com/summerhouses/pressure-treated-traditional-summerhouse/

I'm planning to do the following:

Rockwool or celotex insulation on the walls, roof and ceiling.
12mm plywood boarding on the walls, roof and ceiling.
Install a small 2.5kw stove/wood burner
Solar power

The solar panels part is the bit I have no idea about. Our garden is east facing so the roof will get around 10 hours of daylight in the summer and around ~5 hours in the winter.
I'd like to be able to run a TV in there as well as power for a laptop, phone charger, plug for charging 18v batteries, lighting and possibly a 3D printer. What's the best way to determine the size of the panel and inverter to power these? I was thinking of a 300W panel with a 1600W inverter. Does this sound sufficient? What size batteries would I need for this? Any help is always greatly appreciated

 

[Haze]

Slightly off top, I would not have a 3d printer out there unless it's heated all year round, fillament is effected by humidity

 

[sovietspybob]

How long do you plan to watch TV in there and how often?

Work out your use in watts per day and go from there.

Not sure what TV's draw nowadays, 100w maybe? Lights are easy enough a few watts to light it up and again same for a laptop charger say 65w normally. Are you planning on working in there full time or just a couple of hours in the evening?

Say at 3 hours you may be drawing 200watts an hour so 0.6kwh needed just size the batteries up to suit, so a 12v battery of 110amp hours would be 1.3kwh so about right. You normally don't want to take lead acid batteries past 50% of their capacity or you may damage them, so if you wanted to run all day for 8 hours you'd need at least 2.

Then make sure they're proper deep cycle ones (leisure batteries) don't try and use car batteries as they're not designed for the depth of discharge you'll need. I'd suggest running as much as you can natively off the 12v and just what you need from the inverter as there'll be losses associated with steeping the power up. For example if you can get a 12v telly designed for use in a caravan/boat it might be better.

In the winter solar does produce 4/5ths of &%*$ all, we have 2KW of panels on the house and can make 1-1.5kw easily most of the sunnier days in the summer but can struggle to do a couple of hundred watts in the depths of the winter. Again it's a simple calculation, if you assume in the winter you may produce 50w from a 300w panel for 5 hours you'll be putting 250wh back into your battery so could only run the theoretical load above for just over an hour. You'll have to do research into what you think you could realistically generate from a panel in the winter in your location.

Oh and make sure you have a proper solar charge controller which is spec'd to what you need, a lot of people don't seem to realise you need one and that you can't wire panels straight into a battery.

 

[panthro]

Thanks for the detailed reply!
I'd like to work from there a few hours a day as I'm mostly working from home, it would be good to break the day up and move about! I probably use the TV as a dual monitor set up. I like the idea of sitting in there for a few hours a day with the fire going but I doubt I'd be doing this for long and the only power requirements would be the laptop and TV.
A worst case scenario for power requirements if the solar power wasn't enough would be running a waterproof/amoured cable from the outdoor plugs to the summerhouse. Not ideal but the cost to run a permanent cable from the fusebox is ~£750 based on the quotes I've received, hence why I'd prefer to try the solar route. Any non essential power i.e. the 18v charging can be done in the garage.

 

[sovietspybob]

To be fair i bet you'll spend that much on getting a worthwhile solar setup you must be talking 200 for a 300w panel, 20 for a solar charger, 100 for an inverter, 250+ on batteries then associated cabling and stuff.

I have a very small solar setup in my shed, 20watt panel into some old UPS batteries but that's just for lights and a small fan to move the air for an hour a day. I find it really interesting and if it were me i'd probably do it for the interest of being 'off grid' but i do doubt the practicalities if you just want it to work all year round for a decent chunk of the day without spending a lot of dosh.

 

[d_brennen]

Cost wise, it'll take a long time to recoup the cost instead of just using the mains... But I appreciate you may value the DIY factor (as do I)

 

[panthro]

To be fair i bet you'll spend that much on getting a worthwhile solar setup you must be talking 200 for a 300w panel, 20 for a solar charger, 100 for an inverter, 250+ on batteries then associated cabling and stuff.

I have a very small solar setup in my shed, 20watt panel into some old UPS batteries but that's just for lights and a small fan to move the air for an hour a day. I find it really interesting and if it were me i'd probably do it for the interest of being 'off grid' but i do doubt the practicalities if you just want it to work all year round for a decent chunk of the day without spending a lot of dosh.

I'll most likely buy 2nd hand off eBay or FB marketplace. I've seen some inverter and battery set ups for £300-350. Mainly doing it for the DIY aspect and just to see if I can do it. I'm more excited about putting the small wood burner in as we don't have one in the house.

 

[Diagro]

Slightly off top, I would not have a 3d printer out there unless it's heated all year round, fillament is effected by humidity

Put in a heated filament box or a sealed container. Will be fine. i have 30KG of filament in my unheated garage, its all fine.

 

[Diagro]

How long do you plan to watch TV in there and how often?

Work out your use in watts per day and go from there.

Not sure what TV's draw nowadays, 100w maybe? Lights are easy enough a few watts to light it up and again same for a laptop charger say 65w normally. Are you planning on working in there full time or just a couple of hours in the evening?

Say at 3 hours you may be drawing 200watts an hour so 0.6kwh needed just size the batteries up to suit, so a 12v battery of 110amp hours would be 1.3kwh so about right. You normally don't want to take lead acid batteries past 50% of their capacity or you may damage them, so if you wanted to run all day for 8 hours you'd need at least 2.

Then make sure they're proper deep cycle ones (leisure batteries) don't try and use car batteries as they're not designed for the depth of discharge you'll need. I'd suggest running as much as you can natively off the 12v and just what you need from the inverter as there'll be losses associated with steeping the power up. For example if you can get a 12v telly designed for use in a caravan/boat it might be better.

In the winter solar does produce 4/5ths of &%*$ all, we have 2KW of panels on the house and can make 1-1.5kw easily most of the sunnier days in the summer but can struggle to do a couple of hundred watts in the depths of the winter. Again it's a simple calculation, if you assume in the winter you may produce 50w from a 300w panel for 5 hours you'll be putting 250wh back into your battery so could only run the theoretical load above for just over an hour. You'll have to do research into what you think you could realistically generate from a panel in the winter in your location.

Oh and make sure you have a proper solar charge controller which is spec'd to what you need, a lot of people don't seem to realise you need one and that you can't wire panels straight into a battery.

Solae cells actually produce more in the winter temps. Its just the clouds that ruin it

 

[sovietspybob]

Solae cells actually produce more in the winter temps. Its just the clouds that ruin it

Lol yeah that was badly worded, if you can someone articulate the panels in the winter to get them more upright you'll make more but our cloud cover and general lack of daylight hours really does hinder.

 

[sovietspybob]

I'll most likely buy 2nd hand off eBay or FB marketplace. I've seen some inverter and battery set ups for £300-350. Mainly doing it for the DIY aspect and just to see if I can do it. I'm more excited about putting the small wood burner in as we don't have one in the house.

In that case then yeah totally go for it, just do the sums on the power requirements and size the batteries and panels accordingly and you should be fine.

 

[Psycho Sonny]

Would be interested in what you buy but I think you essentially want a very large battery and therefore if you don't use it for a few days at least in winter the tiny amount of solar should help keep it topped up. Bare minimum 3 panels I would think which is 1200W.

Jerry rig everything made one recently for his barn but he buys top end expensive kit usually.

 

[Ross1234]

I would suggest this setup https://www.mobile-solarpower.com/the-classic-400-watt-rvs-vans-buses.html
Or if you want to be very sure it won't run out of power https://www.mobile-solarpower.com/the-off-grid-king-power-anything.html

Personally I would go for the Lithium Iron Phosphate batteries rather than sealed lead acid as they work out to be more economical fairly quickly. You can discharge them much deeper and get consistent output, and they will last for a lot more cycles.

 

[Duke]

Sounds a lot of flaff rather than just running a mains cable there and not having to worry about how much you're using?

 

[Psycho Sonny]

I would suggest this setup https://www.mobile-solarpower.com/the-classic-400-watt-rvs-vans-buses.html
Or if you want to be very sure it won't run out of power https://www.mobile-solarpower.com/the-off-grid-king-power-anything.html

Personally I would go for the Lithium Iron Phosphate batteries rather than sealed lead acid as they work out to be more economical fairly quickly. You can discharge them much deeper and get consistent output, and they will last for a lot more cycles.

you recommend us buying kit from america?

 

[~Divine~Wind~]

Sounds a lot of flaff rather than just running a mains cable there and not having to worry about how much you're using?

As much as I like faffing about and playing with new toys... I'm with Duke on this one

For the minimal power this will supply I think it'd be easier, faster and more convenient to just run an armoured cable to the main property.
As for the £750 quote you've had... I'd looks to see how much the required length of cable is first, not sure on post covid prices

It's not hard to run yourself and I'd imaging the larger portion of the labour cost is burying the cable, that's easy done just time consuming.
Put the cable in place yourself then have a sparky come round to hook it up if yer unsure.

 

[Rroff]

To be fair i bet you'll spend that much on getting a worthwhile solar setup you must be talking 200 for a 300w panel, 20 for a solar charger, 100 for an inverter, 250+ on batteries then associated cabling and stuff.

I have a very small solar setup in my shed, 20watt panel into some old UPS batteries but that's just for lights and a small fan to move the air for an hour a day. I find it really interesting and if it were me i'd probably do it for the interest of being 'off grid' but i do doubt the practicalities if you just want it to work all year round for a decent chunk of the day without spending a lot of dosh.

I'd spend a bit more on the solar controller/charger - I was using a cheap (actually sub £20) £20 jobbie with some UPS batteries and it trashed them.

This time of year you need a fairly decent solar array (probably 1.2kw minimum) if you want to daily generate enough to run a laptop, TV and lights for a few hours - while even 200 watt would probably do it in summer. You'd probably want a pure sine wave inverter really for a mix of electronics and they get expensive.

It is a setup really for convenience and/or for a bit of tinkering as you won't break even on the costs any time soon.

I'm currently using a mix of Renogy and Photonic Universe gear with PU 100ah gel batteries, 1000 watt Renogy pure sine wave inverter and Renogy Voyager controller (MPPT would have been better probably).

 

[sovietspybob]

I'd spend a bit more on the solar controller/charger - I was using a cheap (actually sub £20) £20 jobbie with some UPS batteries and it trashed them.

This time of year you need a fairly decent solar array (probably 1.2kw minimum) if you want to daily generate enough to run a laptop, TV and lights for a few hours - while even 200 watt would probably do it in summer. You'd probably want a pure sine wave inverter really for a mix of electronics and they get expensive.

It is a setup really for convenience and/or for a bit of tinkering as you won't break even on the costs any time soon.

I'm currently using a mix of Renogy and Photonic Universe gear with PU 100ah gel batteries, 1000 watt Renogy pure sine wave inverter and Renogy Voyager controller (MPPT would have been better probably).

Yeah tbf all good points, i'd want to spend a decent bit on a controller if i was doing it myself and like you say it's quite amazing how much solar you really need in the winter for the most basic stuff.

If you had a cabin in the woods miles from anything it's a really interesting project, but at the end of the day if you can just run a cable there for less than a grand that's kind of a no brainer unless you're super into it as a hobby.

 

[Ross1234]

you recommend us buying kit from america?

No sorry, not what I was suggesting. Just copying the general circuit design as they are well thought out with equivalent components sourced in the UK.