Solar panels on garage (garage is 35 meters form the house) loses ? - Page 1
Forum section: electronics / general

author: onesixright
author_rank: Frequent Contributor
timestamp: January 13, 2019, 12:32:52 pm
content: Hi All,If I would place 3-4 Kw solar panels on my garage, which is placed ~ 35 meters from the house, would that be feasible?- Would it be better to put the inverter in the garage or in the house?- What type of cables would you need (for minimal loss) to transfer it from the garage to the house?Im asking because the garage has a tilted roof, and that's full south. The house has also a tilted roof, but sits north. So logical wise the angle for the garage would be better suited than that of the house.Thanks all! (as always!)--36R

author: capt bullshot
author_rank: Super Contributor
timestamp: January 13, 2019, 01:13:13 pm
content: Put the inverter inside house, preferable a cool area, e,g. cellar, and keep the AC wiring from the inverter to the panel short.Losses on the AC line usually are higher due to lower voltage (230V vs. 300 ... 400V at the DC side).Solar installations here often have single wire 6mm^2, double insulated for the DC side, and 3 * 4mm^2 for the AC side for your power range, so this is another reason to make the DC cables longer for lesser total losses.

author: Richard Crowley
author_rank: Super Contributor
timestamp: January 13, 2019, 02:21:32 pm
content: How is it possible to arrive at a practical answer without knowing the voltage of the DC side?Assuming you want to minimize the cost of the wiring which would imply that you would choose whichever option operates at the higher voltage. The lower the voltage, the larger the cable required for equivalent power. Larger cable = higher cost.

author: Ian.M
author_rank: Super Contributor
timestamp: January 13, 2019, 03:01:15 pm
content: OTOH having a heavy duty AC radial circuit to the garage brings other benefits, e.g. if you ever want to use high powered tools and equipment in the garage, and its almost certainly going to easier to protect a 230V AC circuit against overload and earth leakage faults.

author: nctnico
author_rank: Super Contributor
timestamp: January 13, 2019, 09:47:55 pm
content: I'd put the inverter in the garage. The DC wires from the solar panels will always carry high voltages so you'll need a breaker in the garage anyway.

author: Red Squirrel
author_rank: Super Contributor
timestamp: January 13, 2019, 09:59:41 pm
content: Probably easier to put inverter and batteries in garage. That way you can get away with like 12/2 wiring to the house running AC, much cheaper and easier to work with. Keep in mind if the garage is not heated then you do lose battery capacity, but with the money you save in cabling you can just add extra capacity.

author: onesixright
author_rank: Frequent Contributor
timestamp: January 13, 2019, 10:05:47 pm
content: All thanks for your help.To clarify. thinking of it, ironically the mains comes in from the net-provider at roughly the place of the (newly to build) garage. It also brings 400 V to the house. So maybe It would be easier to put the inverter in the garage (does that need to be heated, can get cold there ~ -15), and connect the inverter direct behind the mains entry?

author: Red Squirrel
author_rank: Super Contributor
timestamp: January 13, 2019, 10:12:31 pm
content: I wanted to build a box to heat my solar equipment in my shed but never got around to it and it got too cold to work in the garage. I've had my charge controller and inverter work in -30's. Though the inverter is usually turned off as I don't produce enough to keep up with the idle run current, but it does run when I turn it on. The charge controller LCD is kinda slow though... lol. Ideally you probably want to build a small insulated cabinet to house all that stuff in and it should ideally keep itself warm from it's own heat. Same with batteries been wanting to build an insulated box for them but never got to it. I snow shoe back there to check it out once in a while to make sure the battery is at full capacity.

author: ahbushnell
author_rank: Frequent Contributor
timestamp: January 14, 2019, 02:34:49 am
content: Quote from: onesixright on January 13, 2019, 10:05:47 pmI would worry most about the batteries. When they get cold you need to slow down the charge/discharge rate.

author: onesixright
author_rank: Frequent Contributor
timestamp: January 14, 2019, 08:28:25 am
content: Quote from: ahbushnell on January 14, 2019, 02:34:49 amI'm not sure if I would choose a battery setup. I'm working from home, so for me electricity generated is being used often directly (floor-heating, etc.). Unused I can sell back to the provider, (of course at a shitty rate...).But anyway, its a good point to think about !