Garage System Information Needed

[DenverGuy]

I share a detached garage with a neighbor. We just found out that both garage's electrical use are billed to her, so we need a solution. I was wondering if it was worth going solar on my side. The roof gets sunlight all day. There are no trees. I would like to install an off-grid system for my side to power the 540W, 120VAC Liftmaster opener and two LED lights. I realize the surge when starting the opener is much higher that 540 watts. For what it's worth, the opener has a backup battery.

I'd like a solution, but I don't want to spend $3000 for it.

Any suggestion regarding what's needed and if it's worth considering?
Thanks,
Jeff

[azdave]

Installing an off-grid system for that reason is dumb. I would pay to have a second meter installed by the utility before I would ever think about PV solutions. If all you are running is a garage door opener and some LED lights you would save thousands by just giving you neighbor $100 a year (which is generously way more than those items would ever use).

[SunEagle]

Hello DenverGuy and welcome to Solar Panel Talk

Installing an off grid system will rarely pay for itself so if the idea is to save money you should forget it. The reason is the cost of batteries just do not have an ROI unless you are paying over $0.40/kWh for electricity. Based on past off grid system costs it may be as much as $1500/kWh the system can provide daily so $3000 may only get you 2kWh a day which is not cheap.

Also a grid tie system on the garage is probably going to cost much more than $3000 so again it is not going to save your money quickly where an ROI may be up to 10 years.

Unfortunately IMO the cheapest way would be to just pay your neighbor some amount for what you would use in electricity for the garage.

[DenverGuy]

SunEagle, thanks. To clarify, I am only looking for an off-grid system. ROI isn't important as it is not about saving money. Do you think it would cost more that $1000 for the equipment needed to just power the opener?

[organic farmer]

My local Harbor Freight store has 100w solar panel systems for $200. https://www.harborfreight.com/100-wa...kit-63585.html

I would suggest that you get three of them.

Then a 12vdc battery-bank with 1000ah on it. and a 500w 120vac inverter, and you would be all set. To open and close the garage door once a day.

[SunEagle]

SunEagle, thanks. To clarify, I am only looking for an off-grid system. ROI isn't important as it is not about saving money. Do you think it would cost more that $1000 for the equipment needed to just power the opener?

Well you first determine the amount of watt hours you will use each day. From that you can size your battery and solar panel wattage. Remember you will also need a Charge Controller and DC to AC inverter big enough to handle the surge of the door opener motor.

Take a look at what organic farmer provided and estimate the cost of that equipment. It may be less than $1000 but you may need new batteries after a year or so.

[DenverGuy]

SunEagle, it's only used twice per day, max, and does have a battery backup. Is it hard to tie three sets of panels to one controller?

[SunEagle]

SunEagle, it's only used twice per day, max, and does have a battery backup. Is it hard to tie three sets of panels to one controller?

You would need to wire each set in parallel to the CC. That will require fusing for each set. You may be better off just getting a single 300 watt panel and an MPPT CC.

But again what battery are you getting and will you be able to provide a C/10 charge rate where C = the battery Ah rating?

[DenverGuy]

Do you think this would work? https://theinverterstore.com/product...rter-off-grid/