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Solar Power - Garden Office/Workshop

jagdesign

pfm Member
I'm hopefully going to be building a garden office/workshop once we've moved and am pretty keen to understand options for it being predominantly powered 'off-grid' via solar.

Most of the time I'll be running
- Laptop + Monitor = about 100W I'd guess
- Some lights, not sure how many yet
- Probably an electric heater in winter/fan in summer
- A small class D amp running speakers
- And probably some USB peripherals/chargers

That's the 'office' side - hopefully the other half will be the 'workshop' and that's where I'm guessing the power would likely need to switch to mains once a 1200W mitre saw and similar tools are running on and off throughout the day, or perhaps not?

The split of usage is likely to be around 90% office/10% workshop. I'm assuming that having enough energy storage (batteries) to run the workshop for a day, would likely increase the payback period significantly, i.e. most of the time, that capacity is unnecessary.

So any thoughts on panels, inverters, storage etc, much appreciated. Cheers!
 
Add all your loads for a total
say 500w office micro system circa £900
1200w saw bigger system 2,000w £ 2199
or full monty for house/office/workshop 3.6/4wp
£6/8k same as a Naim PSU & no more lecky bills ever " the sun never sends you a bill " and save the planet + hifi sounds better than powered from the mains


Goal Zero Yeti 500X Lithium Portable Power Station, with Boulder 50 Solar Panel | Leisure Outlet

2kW DIY Solar Panel System Kit with Enphase IQ7A Microinverters | DIY (zerohomebills.com)

ABB Fimer REACT2-UNO-3.6-TL 4kW Modular Li-Ion Battery Storage (zerohomebills.com)


 
I would be very surprised that you can make a practical off grid solution to that requirement. Have you got spare land for a larger array?

Acquire some old car batteries to make a storage farm? Storage definitely needed and will have to be electrical rather than hot water or heat sinks.
 
Based on my (admittedly limited!) experience with solar panels on my motorhome then I think it'd likely be quite expensive to put in place a solar option for that on a year round basis - particularly if you need to run a heater. In the summer the solar worked pretty well (with 160W of panels and a 120AH gel battery) although we're not big users of power in the motorhome (no tv for example), however in winter the panels don't really produce anything useful when we're using the motorhome (although they do a decent job of keeping the battery fully-charged when the motorhome isn't in use).
 
@daytona600 thanks, and lol at the Naim PSU comment

At some point I'd hope to be driving a leccy car, so charging that via solar at the weekend would be the dream too, but not sure about the entire house at this stage. I quite like the toe dipping nature of starting with the shed!
 
I’ve been off grid for a couple of years now, I’ll throw in my two cents.

What you want is mostly do-able but definitely not an electric heater. On a cold dark winter day you’ll be lucky to get 10% of your rated power for six hours from your panels.

I run a 2kW Chinese diesel heater in the shoulder seasons. It’s great.

If you want to run saws and things you need a big (expensive) inverter to handle the start current. Also, lots of panels and batteries.

lead acid batteries, even deep cycle ones, want to be charged all the time. The rule of thumb is to keep them above 70% most of the time. I get anxious if mine ever go below 50%.

LiFePO4 batteries are pretty affordable now and the BMS protects them from overcharge, over discharge etc. they’re a lot safer than Li ion because they don’t get thermal runaway and burst into flames. The new ones claim 6000 100% cycles.
 
I think you'd be better served being connected to the grid, you'll also be financially better off unless you like investing large sums of money with no return.
 
The small electrical loads are easy enough. Solar is fine, and a small inverter. The heater and saw, not without a bit investment. I'd run off grid 95% and run a power cable across for the 2 days a year when you want lots of power. This is what I do in the garage, which has a crappy 5A supply and a breaker. Most of the time, no problem. When I plug in the welder I run a 13A cable from the house.
 
I think you'd be better served being connected to the grid, you'll also be financially better off unless you like investing large sums of money with no return.
average house
£1000-1200 annual lecky bill minus putins + 20% increase per year for life
£6000-8000 total cost & never have a bill again for life
connected to grid or have your own grid
 
average house
£1000-1200 annual lecky bill minus putins + 20% increase per year for life
£6000-8000 total cost & never have a bill again for life
connected to grid or have your own grid

He only wants to run the garden office from solar, if its the whole house he'll still have to connect house and office as if its on grid, also you haven’t factored in failure of the inverter and possibly some of the panels, plus regular cleaning of the panels if you want full efficiency along with efficiency drop in the summer due to increase in panel temperature, also the cost of battery storage to ensure you can run the house 100%. And good luck also charging your car during winter months. Also perhaps he doesn't have a spare £8000 to drop on the project.
 
see post above ( 500w office micro system circa £900 ) or £400 for low cost chinese

off grid for 10years now
failure of the inverter - lifetime warranty if fails swap out for new inverter
failure of the panels - 25year warranty
regular cleaning of the panels - big shortages of rain in Scotland
efficiency drop in the summer due to increase in panel temperature - see above
spare £8000 to drop on the project. - £8000 in one hit or £1500 x 25years + £37500
 
I'm definitely leaning towards the office only (500W) ish setup and <1k would be nice - don't really want to invest more than that at this stage.

@daytona600 the portable power station setups look pretty neat, but I don't love the idea of the cells being integrated and potentially limiting the lifetime. A modular version of this with separate cells would be good - I need to google.

Any particular advice on solar panels that I should consider? Size, mounting, manufacturer, tech, etc?
 
The latitude of your home will also matter when trying to make a system work. Where are you?
 
Buy a power wall (£8k)
Use cheap overnight electric to change it
Draw it down during the day and run every thing ...saw bench included

Ps ...if you're serious about £1k budget .. forgot the whole thing...no chance of anything useful
 
Recently the overnight electricity costs have been quite high unlike last winter when we got relatively cheap power.
 
The latitude of your home will also matter when trying to make a system work. Where are you?

Sunny (?) Sussex

Ps ...if you're serious about £1k budget .. forgot the whole thing...no chance of anything useful[/QUOTE said:
I dunno, still something appealing about running the home office for free, which I think in the summer months is just about doable for <1k with some of the DIY options, maybe?
 
But how will you power it in the winter? It’s unlikely to make sense if it takes twenty years to properly cover the costs.

A workmate did it just for the light in his shed. He bought the kit for less than the cost of laying the cable etc for a mains connection.
 
A practical low budget solution:

Drop the battery. The garden shed I assume will have limited roof space, so there won‘t be much energy to store anyway.

Distribute the panels you can accomondate evenly east and west to maximize the time of day you harvest energy.

If possible connect the shed to your main house too. Appliances (Fridge,WiFi,HiFi) will require around 250-300w per hour. Plus your office. If you can cover that by solar during most part of the day, you‘ve already saved quite a bit and have lowered your general electricity mains consumption by quite a margin.

To reduce costs even more, hunt for cheap old stock panels, leftovers or s/h. 200w panels can be had for a few quid s/h. Modern panels will do 370-410w but come innat 150-200 quid. I‘d try an find something around 250-270w for roughly 50quid a piece.
 


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