Garage/man cave solar power

[Bluemotion]

It’s a deep thought, I’ve a double garage which is my making cave and wonder if I can do a budget solar power project on it. I have no knowledge at all about that sort of thing but what would a roof full power?

 

[voipio]

Depends on the size and facing direction of the roof. A south-facing pitched roof, free of any shadowing by trees, or anything else, is just about the best orientation. Whatever solar panels you get on the roof, consider that, on a cloudy day, you'll be lucky to get 5 to 10% of maximum power, so a 300Watt panel will only deliver 15 to 30W under cloudy conditions. Depending on how multiple panels are interconnected, even partial shading of a single panel can have a profound effect on the output from the whole array. The best option would be to have a substantial bank of batteries to store the energy from the solar panels, and then draw off those using an inverter. It's worth sitting down and working out the typical power and energy requirements of the mancave by e.g. lighting, machinery, power tool charging, computer and networking equipment, heating, and suchlike.

 

[gaz1]

with our sun up here very little chance of getting good power

solar system id consider just sticking to is battery and led lights for the lighting

for using the power tools your going to have to add extra panels and banks of batterys and a convertor

 

[julianf]

Im about to put about 3.5kw on the south facing pitch of our garage roof. I consider it to be very much worth it.

Second hand panels can be had for very little money now. I purchased an entire 4kw setup (panels, grid tied inverter, mounting) for less than £500. At that sort of price anyone with some south facing roof should have an install, as the break even point, even before the current profiteering, was a couple of years, rather than decades.

 

[Bluemotion]

I need to know the basics. I’ve mains power and run many things but I was just wondering if it’s a benefit in today’s world. I have no idea what even one panel can produce and what would be a std size?

 

[voipio]

Work out how much energy (kWh) are typically consumed per day/week/month/year, by the workshop, and how much that costs using the mains. That should give some idea of whether it's worth going ahead with solar panels or not.

 

[julianf]

The way to do it, roughly, is to work out your available area.

Then get on FB market place and see if there is anyone flogging a load of used panels near you. For example, there's an outfit in Cardiff that does ex solar farm stuff, but a domestic seller will, obviously, be cheaper.
Solar bimble in sussex is good for a general idea also.

When youve worked out what you can fit in the space (kw wise) you can browse for inverters. You can get systems that charge batteries and stuff, and, whilst theyre great, and what i would like, hybrid inverters are too new to be cheap on the used market, whilst a standard grid tied one will be way way cheaper. Expect maybe £150 ish for a used SMA Sunny boy (etc).

Dont buy the inverter yet though, as youre only getting a grasp on whats availible. The inverter has to be closely matched to the panel configuration, so panels first.

You can bodge mounting with wood, or do it properly with all the alloy stuff. One will be cheaper but not last as long.

 

[julianf]

Work out how much energy (kWh) are typically consumed per day/week/month/year, by the workshop, and how much that costs using the mains. That should give some idea of whether it's worth going ahead with solar panels or not.

Your comment raises a good point -

For a garage (alone) its probably not worth it, as the items used will be way more than the output of the panels most of the time.

The panels are more like a trickle charger on every day. So they will offset things like your fridge, computer etc. way better than booting up a couple of 3kw compressors.

The savings are like the power - more of a constant (when its light) trickle, rather than somthing to run a 6kw load off.


IF the garage comes off the same electricity contract as the house its well worth it, but if its just a garage that swaps between virtually no load, and loads way over what the panels will produce, then its not so applicable. But again, panels are so cheap now that its still, maybe, worth considering?

 

[voipio]

If the solar panels are connected to the mains via a grid tied inverter, and the output of the panels exceeds the consumption of the whole metered property, the incoming mains electricity meter will basically stop for the duration that the panel output exceeds property consumption. Indeed modern meters can even run backwards, though energy supply companies don't normally use this option.

 

[dyno-tron]

I need to know the basics. I’ve mains power and run many things but I was just wondering if it’s a benefit in today’s world. I have no idea what even one panel can produce and what would be a std size?

Some basics :-
With new panels available at the moment you get approx 200w per square meter.
A 400w panel (more or less about the biggest commonly available - yes, there are some that are a bit bigger) will be approximately 2m x 1m.
Older panels will be physically smaller and less output.
The rated output is only possible if mounted in ideal position and on a bright sunny day. Dull day and you may be lucky and get 10% as others have said.
Panels get less efficient as they get older.
Shading of even just part of one panel affects the overall output of the array. Countermeasures are available but cost more money to deploy.
IMHO - don’t even bother unless you are going to include batteries with the solar installation, so far (3months) our solar battery has provided 540kwh vs 270kwh direct from the panels.

 

[Wildefalcon]

Take a look at emphase products.

In Noddy terms they plug a box into each panel which converts the direct current into alternating current, panel by panel.

Thus one AC wire does the roof. And panels that get shaded don't effect the other panels, and expansion is easy: plug another one in, job done.


The AC wire goes into a box that's wired in before the consumer unit, this box does the safety smarts, essentially to stop the linemen being electrocuted if the mains is being worked on. I think the box can talk to battery systems as well, so you can store electric.

All doable by DIY, subject to inspection and installation regulations in your area.

 

[gaz1]

here you are for you to take a look at

time to go solar i think

good day folks, i have at the bottom end of my property an old wooden hay barn that has not been used for years, as i have now retired i have plans to convert part of it to a log cabin as it faces out across a large pond with scenic views and miles from anyone, the building part and...

www.mig-welding.co.uk

 

[hotponyshoes]

I looked into sticking some on my shed roof recently.
This is a shed by my house rather than a workshop. I use it daily but only stock for the day job. Occasionally I might have a project on at home when I have a welder/plasma/grinders etc running for an afternoon.
So, a bit like said above, it's one or 2 strip lights running (in the dark when the panels aren't working) or, way in excess of what the panels will produce.

My first thought was to fit some panels and a charge controller, stick a couple of old lorry batteries in the shed and swap the lights to 12v led strips.
I figured it would be easier just to change the fluorescent tubes for 230v leds though and that would only be a 10min job and still save me some money!

The other idea I had was to just fit some panels and use the output to charge up power tool batteries.
I could do that in addition to the 12v lights by adding a small inverter and I have enough battries that I could leave half of them on charge all day ready for the next day.
I then thought that if I could find 12v car chargers for 18v tool batteries I could skip the inverter as well.
Those were expensive though.

In the end, as mentioned, I figured out the best return on them would be offsetting the power of stuff that's on a24/7 like the freezer.
I have power between the shed and the house so, after pondering it for a bit, it made more sense to me to send all the power back to the house. That's as far as I've got.
Next job is to see how much power the fridge/freezer are using when nothing else is on and work out if the shed roof is big enough to cover that...

 

[Burdekin]

A mate has solar on his shed and also ground source heat pump for his house heating so his bills are minimal.

I don’t know anything about it so some stuff from his Facebook.

4kW of solar on my workshop feeding a Fronius inverter which talks to my Victron gear at the front door. It can all be remote monitored and settings adjusted from anywhere. Victron are such a great company, privately owned and passionate about quality.

 

[Bluemotion]

Well all that above sounds complicated!! Seen a few barges on a local canal nr me which gave me the idea in the first place. My plan was to possibly power trivial things, possibly water cylinder, tool battery chargers etc. I also wanted it on a cost effective budget as it looks like that’s the way the barges were done.

 

[Jack_K]

A small system with a single approx 100ah battery and victron 75/15 with one suitable panel will work well and be reliable to do basic stuff. I upgraded a system for an opal mining claim with a victron 75/15 and reused two old (30+ years) 60w panels. It only gets used for a couple of weeks a year but it provides lighting, radio and a 12v water pump for usually four people to live.

With an inverter you can also then run tool chargers etc.

I got given 20 used panels but until someone moves back there permanently it isn't worth buying the equipment to be able to use them.

 

[gaz1]

Well all that above sounds complicated!! Seen a few barges on a local canal nr me which gave me the idea in the first place. My plan was to possibly power trivial things, possibly water cylinder, tool battery chargers etc. I also wanted it on a cost effective budget as it looks like that’s the way the barges were done.

narrowboat reference

 

[voipio]

Useful video, apart from getting his Amps and Amp hours confused, and not stating how many solar panels there are on the boat, or their capacity.

I was looking at a 2.2kW solar array the other day, when it was quite cloudy. The array was generating about 42-43Watts, so ~2% of nominal. Under these conditions, a 4kW solar array on the garage roof would be producing something in the order of 6-7 Amps to a 12V battery, so it would take getting on for 30 hours of cloudy daylight to fully charge his 330Ah canal boat battery from 50% discharge.

 

[hotponyshoes]

Well all that above sounds complicated!! Seen a few barges on a local canal nr me which gave me the idea in the first place. My plan was to possibly power trivial things, possibly water cylinder, tool battery chargers etc. I also wanted it on a cost effective budget as it looks like that’s the way the barges were done.

If you had provision for 2 immersion heaters in a standard hot water tank I suppose it would be pretty simple just to send the output from some panels directly to one of them.
Nothing else to wire in or worry about then.
I doubt it would ever get the tank right up to temp but I'd wire it through the thermal cut-out just incase!
If you did have enough panels to heat a whole tank then some sort of temperature controller would be needed.