2kW Garage Power Supply

[douglasheld]

Hi all, I've completed my first project. Location is London England, on my detached garage roof.

• single Nicesolar 120W monocrystalline panel with MC4 connector cables and a 20W PWM charge controller (starter kit sold on Amazon, the listing is now gone)
• I built an approximately 60˚ frame out of 21mm slotted channel steel and A4 stainless machine screws. This sits on the roof on nylon feet, with some adhesive 3M VHB pads to hold it in place without damaging the roof material.
  • I don't have a photo of this frame - but it is simple
  • the roof surface is "box section composite roofing sheets 40mm sandwich insulated" - probably polyester or painted steel.
• 130 Ah 12V deep cycle battery, sold on EBay (https://www.ebay.co.uk/itm/274087465400)
• Some simple electro-plated brass battery terminal connectors (https://www.amazon.co.uk/gp/product/B091J24DXX)
• 12V 250A circuit breaker (https://www.ebay.co.uk/itm/124618845893?var=425550653287)
• 2 AWG pre-crimped cable (https://www.amazon.co.uk/gp/product/B0B5G9FGKY)
• 12V -> 240VAC 2000W pure sine wave inverter (sold on Amazon, the exact product is now gone https://www.amazon.co.uk/gp/product/B0B11VT378 )
• I even bought an 18mm OSB3 panel off of EBay... (https://www.ebay.co.uk/itm/224604576826?var=523413055972)
  • It's nice to have a panel pre-cut and delivered!
• a simple food-service stainless steel tray (https://www.amazon.co.uk/gp/product/B0BBWM71KB)
• Some really simple USB LED lighting strips (https://www.amazon.co.uk/gp/product/B0B83WGCVQ)

Goal
So my goal was to have some fun, create something, get to understand the basic of solar energy in my region, and to have the ability to run power tools, a (1700W rated) shop vac, and add lighting to my garage. The garage isn't attached to my house, and I didn't want the hassle of a utility-provided electrical supply there. Instead, I simply asked the freeholder for permission to try this out on the building roof. Meanwhile, the interior space of the garage is mine to work with.

Result
Well, it was great that I had my setup to power my drill to put the electrical panel together.
Notice I used the pieces of the stainless steel shel upside-down, to make a tray with a lip to hold the battery. I think the wood screws in the 18mm OSB3 are going to be strong enough to hold this heavy battery.

I've also vacuumed out my car several times - something that's been seriously difficult for me to do before my inverter setup. I'm looking forward to doing more work in the garage now - using my table saw etc. to build out further.

If I need to I might add another panel with a second identical battery in parallel.

Finally, when we buy our next house in the next few years, I am looking forward to installing a home energy storage system.

Photos

 

[Crowz]

Well now your addicted. It just gets fancier and more expensive from here

 

[douglasheld]

I do have a question for the forum... this is about use of the circuit breaker.

Do you reckon I've got the circuit breaker in the correct capacity, and optimal location? I was thinking it's likely the negative 12V is connected to the inverter chassis. One risk is I have a wrench on the positive terminal, touch the chassis and melt the wrench.

Also, is there a safe way to test that the circuit breaker trips? I tried short-circuiting it across the fully charged battery - predictably it made a big spark, and it also melted some of the threads on my terminal connector, but it did not actually trip open. I'm afraid to try it again because of the risk that the cable I'm holding will weld in place and I won't be able to remove it.

It could be that I actually need a smaller circuit breaker... my vacuum is 1.7kW so maybe I should be going with 150A instead of 250A.

 

[douglasheld]

The other thing I'll note is that I found it nearly impossible to get a wall-mounted battery tray. I often see banks of batteries on the floor, but I didn't want to lose the floor space in my garage unless there's no other safe option.

I think this holder is likely strong enough... but I do understand a failure would be catastrophic. I'd appreciate thoughts on that.

 

[sunshine_eggo]

Cheap breakers aren't to be trusted. Ebay isn't the best place to buy quality breakers.

Check prices of brands like bluesea systems, littlefuse and eaton for what quality breakers cost.

Breakers protect wires, not hardware. Breakers should be sized for the wire: 1.25X wire rating here in the states, but a 250A breaker for a 2kW inverter is about right provided those sad cables that came with the unit are rated for 200A.

Breakers don't break instantly. It might take several seconds. Sample curve to illustrate concept. Not to be applied to your breakers:



If that applied to our breaker, a 1250A current wouldn't trip it in less than a second and maybe as long as 7.

Your breaker claims 3000A interrupt capability. If you push more than 3000A through it, it won't break.