Small solar energy system to power a garage/workshop?

Forums › Home Workshop DIY › Small solar energy system to power a garage/workshop?

1 | 2 | 3

241 posts

Master Geek

#1012125 24-Mar-2014 23:26

We have a holiday house which is off the grid. We've tried big (ish) inverter systems with mixed results - providing 240v means people expect to be able to use high draw appliances.

The most successful systems have been very small 12v light only ones, with a 5w panel and a little gel cell battery. These will drive two or three MR16 Led elements which work really well as little worklights hanging on their cables from the ceiling.
The rationale behind using lots of small systems was that we got sick of a single failure taking out the whole house, splitting it up means we usually only lose one part at a time and can just live with the problem until daylight gives us the opportunity to fix things.

The overall effect looks quite nice too: in our main room we have 12 of MR16 lights all hanging on a plane just above head height. You could put a system like this together for a couple of hundred dollars.

If you want some MR16 Leds PM me, I have some knocking around.

richms

28191 posts

Uber Geek

Trusted

Lifetime subscriber

#1012129 24-Mar-2014 23:29

If you are getting 12v MR16s I can fully recommend these ones off ebay - http://www.ebay.com/itm/301021055424 - not tried dimming the ones I have got yet as theyre all in outdoor lighting running off a big switchmode power supply, but great illumination and not much fringing at the edges and no hotspotting like the ones with 3 or 4 small LEDs do.

I got the 6w 4000k ones. Best LEDs so far I have got.

Richard rich.ms

Technofreak

6530 posts

Uber Geek

Trusted

#1012131 24-Mar-2014 23:31

I did something similar about 10 years ago. It was for an aircraft hangar where I wanted to run a 12v vehicle winch and 5 X 100 w 12 V lights, (car driving or flood lights). I did consider an inverter for running a vacuum cleaner but didn't install one in the end.

It consisted of one solar panel, one deep cycle battery, a charging controller and miscellaneous bits and pieces, plus the lights and the winch. I would use LED lights now. I kept everything at 12v as this was the voltage from the solar panel and it kept things simple.

One of the issues with low voltage incandescent lights is the current draw. If you use low voltage incandescent lights you need to ensure you use a cable size that is commesurate with the current draw and the length of cable run, to ensure there isn't too much voltage drop.

This is a quite low capacity system, planned on the lights being used for an hour per week and the winch just over one hour per week.

Back then it cost about $3000.

When designing the system you need to know what sunshine hours you can rely on, especially in the winter, as this coupled with your expected load will determine how many panels you will need and the battery size.

I don't have time to dig out all the info now but am happy to do so I you think it will help.

Sony Xperia XA2 running Sailfish OS. https://sailfishos.org The true independent open source mobile OS
Samsung Galaxy Tab S6
Dell Inspiron 14z i5

Niel

3267 posts

Uber Geek

Trusted

#1012152 25-Mar-2014 02:51

We still do not know how long at a time or how often you want to run the lights.

Just the other day I got a DIN55 recovered battery from Metro Batteries for $40, and $10 discount for 2 trade-ins of which one was dead and the other failing. They claim the batteries are typically less than 3 years old, and appears to come from cars that were written off or imported cars with battery replaced or other recovered batteries. My previous recovered battery which was $50 lasted ~6 years.
http://www.trademe.co.nz/Members/Listings.aspx?member=4913882

Alarm batteries especially are not rated for fast discharge, they cannot sustain the current, intended for 10h-20h discharge. Our company pays $6 for a 7Ah alarm battery out of China. Unfortunately I cannot resell them, can only buy one or two every now and again for personal use. In NZ a large factor is that apparently labour and overheads are expensive so customers get charged a lot - not sure that is the whole story though.

I'd either go for cheap recovered batteries, or LiFePO4 cells (about $80 for 12V 10Ah at 1h discharge rate). With LiFePO4 you can charge them using a normal lead-acid battery solar charger, and connect 2 red LEDs (no resistor) in series across each cell for balancing (designed it 2 months ago, tested, validated, and in use at home on my EnviroMower).

Just don't use cheap/nasty mains car battery chargers unless it is for a top-up and you monitor the battery voltage, those $20 chargers will overcharge your battery and destroy it.

You can never have enough Volvos!

nickb800

2719 posts

Uber Geek

Trusted

#1012199 25-Mar-2014 08:41

Technofreak: I did something similar about 10 years ago. It was for an aircraft hangar where I wanted to run a 12v vehicle winch and 5 X 100 w 12 V lights, (car driving or flood lights). I did consider an inverter for running a vacuum cleaner but didn't install one in the end.

It consisted of one solar panel, one deep cycle battery, a charging controller and miscellaneous bits and pieces, plus the lights and the winch. I would use LED lights now. I kept everything at 12v as this was the voltage from the solar panel and it kept things simple.

One of the issues with low voltage incandescent lights is the current draw. If you use low voltage incandescent lights you need to ensure you use a cable size that is commesurate with the current draw and the length of cable run, to ensure there isn't too much voltage drop.

This is a quite low capacity system, planned on the lights being used for an hour per week and the winch just over one hour per week.

Back then it cost about $3000.

When designing the system you need to know what sunshine hours you can rely on, especially in the winter, as this coupled with your expected load will determine how many panels you will need and the battery size.

I don't have time to dig out all the info now but am happy to do so I you think it will help.

NIWA has a tool that can help calculate sunshine hours - refer here

trig42

5814 posts

Uber Geek

ID Verified

#1012217 25-Mar-2014 09:05

pbolger: We have a holiday house which is off the grid. We've tried big (ish) inverter systems with mixed results - providing 240v means people expect to be able to use high draw appliances.

The most successful systems have been very small 12v light only ones, with a 5w panel and a little gel cell battery. These will drive two or three MR16 Led elements which work really well as little worklights hanging on their cables from the ceiling.
The rationale behind using lots of small systems was that we got sick of a single failure taking out the whole house, splitting it up means we usually only lose one part at a time and can just live with the problem until daylight gives us the opportunity to fix things.

The overall effect looks quite nice too: in our main room we have 12 of MR16 lights all hanging on a plane just above head height. You could put a system like this together for a couple of hundred dollars.

If you want some MR16 Leds PM me, I have some knocking around.

We also have an off-grid holiday house, and have gone down much the same path.
We take a spare car battery to the bach and connect it to the house. There are 12V lights in each room. Previously these were halogens, but we have upgraded to warm LEDs - much more power efficient.

I have found some Bayonet to MR16 adaptors (on ebay UK), so now we just pick up old desk/wall lamps at second hand stores, wire them up to the 12V and away we go - switched lights.

We have along set of jumper leads, and if the battery looks like it is getting low (we have a 12V ccfl in the dining area, and when it struggles to start, we know it's low) we connect it to a car and run the car for a while (or put the battery into the car and go for the 2 hour drive to the shops).

We have a stream running through the property, which has a good head - I would like to build a small hydro generator (using Smart Drive motor(s)).

Fred99

13684 posts

Uber Geek

#1012225 25-Mar-2014 09:21

If using inverters to power 230v tools, then as a rule of thumb for start-up current drain, double the wattage of the tool.
For example, I use tools on a 1500 watt inverter. A 700w grinder was getting a bit dodgy (motor stiff/gummed up - it needed a good clean-out). First indication of a problem was that it would trip the overload protection on the inverter.
1000 watt power tools can't be used on that system.
That's running in the back of a ute, with a large deep cycle battery, set up by an auto electrician - it automatically switches between charging the main vehicle battery and the deep cycle battery.
Manual switching is an option until you forget and end up with either no power on site - or a ute that you can't start, automatic switching as above a reasonable compromise. Best option if there's room under the bonnet is to mount a second alternator - dedicated to the deep cycle system. (Some 4WD - like my old Safari - even have a "spare" slot on the crank pulley, so setting up a dual alternator system running off separate belts is relatively easy).
Also don't forget that if you're using a 1500 watt inverter, then 12v current draw is 125 amps - you need seriously heavy cable and connectors etc - or it will come to grief.
That setup will get us through a day's work using power tools intermittently, and most of the time a couple of chargers for battery tools connected. I think the battery is about 200 AH.
Running some LED lights in a shed would be easy to set up for a few hundred $$. To set something up for serious power tool use is another thing entirely.

Sharesies

Trade NZ and US shares and funds with Sharesies (affiliate link).

Dangermouse

43 posts

Geek

#1012561 25-Mar-2014 16:45

What is the actual distance from your house? If you can't run a cable is it feasible to transport batteries on a trolley? Then you'd have no need for solar and could buy a decent battery rather than a crappy 26Ah battery designed to run an alarm system.

About 40m up a good 35% slope so no thanks to wheeling trolleys up and down :-) Think I can get that connected up for less than $500? You can also see how the proximity of neighbours would rule out a generator.

Up to this point I have gotten by with just rolling up a 50m cable and treating it like a long extension cord; while this has worked fine it’s a pain in the bum and I’m trying to work smarter rather than harder. And because it’s awkward and a pain in the bum the temptation is to leave the cable in place which is not very safe and healthy. I really don’t want to dig a 40m trench either…

Do you have Vehicle access to the garage? Just install the inverter in your car and run a lead in when you need mains power.

If the car’s in the garage then there’s very little space left to actually work in unfortunately. Don’t fancy running leads out to the street.

We still do not know how long at a time or how often you want to run the lights.

I did suggest further up three periods a week of three hours duration. If I go ahead with it I’d also want to feed one or more LED security lights on a proximity sensor to illuminate some dark steps which go down along the side of the garage and the steep path which can be a bit gnarly at night; such sensor lights would only be on for a minute or two at a time so wouldn’t add much in the way of a power demand to the system I expect.

wellygary

8328 posts

Uber Geek

#1012579 25-Mar-2014 17:00

Any chance of running a lead from one of the very near neighbouring properties?

Niel

3267 posts

Uber Geek

Trusted

#1012706 25-Mar-2014 20:33

for ~10h a week I'd run a cable. The rules are that if it is underground it needs to be in a proper trench in case someone digs there , but there are no rules that I can find for on the surface. I'd run cable inside UV stable conduit and run it along solid structures like fences and walls wherever you can. Just ensure it is plugged into an RCD if your power board does not have an RCD, and turn it on only when used. I'd suggest a high current heavy duty contractor's extension lead (check cross section, not product name) and draw it through PVC pipe, that way the cable is still well protected even if the pipe gets damaged. For the motion sensing lights, you get solar powered ones with built-in batteries.

You can never have enough Volvos!

Niel

3267 posts

Uber Geek

Trusted

#1012707 25-Mar-2014 20:36

http://www.thewarehouse.co.nz/red/catalog/product/Urban-Solar-Security-Solar-Light-60-LED?SKU=1731480

You can never have enough Volvos!

kiwigander

231 posts

Master Geek

#1012813 25-Mar-2014 22:36

OP, I second Niel's approach. Unless you are particularly keen on the challenge of a micro-solar installation you are going to find it frustrating and ultimately not very effective.

Electrifying the garage with household 230 V, though, I reckon will add to the value of your property.

Is there any chance you could find a sparkie who would work together with you, you doing the grunt work (digging a trench if you wanted, fitting conduit together, drilling holes where needed, preparing surfaces for a switchboard and powerpoints, laying cable) and he doing the mission critical work like connecting to the house switchboard, starting one or two circuits off in a new garage switchboard and inspecting the installation?

If you want to go with photovoltaic power, good on you. But the place for it is at your house.

I'm coming from the perspective of being off grid x 8 years and having had a remote shed electrified - by connecting it to the house supply, not its own photovoltaic system - within the last 2 years.

richms

28191 posts

Uber Geek

Trusted

Lifetime subscriber

#1012832 26-Mar-2014 00:32

Do you have to walk all that way from your house to your garage every time you go out?

Richard rich.ms

Dangermouse

43 posts

Geek

#1012952 26-Mar-2014 09:54

Yep, it's the only street access. Gets your heart going in the morning :-) It does afford marvelous privacy though; we don't get pestered by cold callers that's for sure.

Dangermouse

43 posts

Geek

#1012983 26-Mar-2014 10:22

I hadn't realised photovoltaic systems were so very feeble; I really thought this sort of thing would be pretty commonplace these days.

Ok, so accepting that somehow connecting mains power would be the most sensible solution, let's consider for the sake of argument and obtuseness that I want to pursue the solar option and am only looking for some occasional convenience lighting, say 8-10 12W MR16 12V LED bulbs available on demand for a short period. Is the primary factor here the battery size then and other components stem from that? I don't think cheap, recovered batteries are available to me locally and I'm guessing they don't transport well.

1 | 2 | 3