Where do I install the inverter?

nichtwichtig wrote: »

This is a 3-part question about inverter placement.

I’m finally getting grid-tied solar panels installed next week—4.050 kW DC (STC). Yaay!

The inverter will be an ABB PVI-3.6-TL-OUTD-S-US. (I think it used to be called the Power-One Aurora.)

Question #1:
The best (most convenient) available spot for the inverter is on the north side of the house, next to our tankless water heater and about 9 feet from the electric meter.
Unfortunately, it’s also right outside our master bedroom window, just a few feet from where we rest our heads in the bed!

Does the tankless water heater bother you? The few that I have heard can be quite noisy due to the large gas burner (when compared with a traditional tank type water heater). A typical tankless water heater would could be about 45-50 dba on the low side and something like 65-95 dba on the high side.

I am worried the inverter noise is going to disturb the peace and quiet in the bedroom.

My old Xantrex 3 kWatt inverter is dead quiet (no fan).

The one you are looking at appears to have a fan (at least it has a fan alarm). I would presume that the fan only would run during the daytime (~9am to 3pm)--unless you work nights, I would not worry too much.

If you like to have open windows, may be an issue with fan noise. 50 db is moderate conversation/quiet office/stream burbling.

Also: Since it’s so close to our bed, I am also wondering if there is any electro-magnetic radiation/noise/interference to worry about…?

Depends if you are somebody who is worried about low frequency radio waves (60 Hz) or not. We had an office that was build behind the three phase transformer for our office building. No complaints other than the monitor (CRT type) would "swim" sometimes from the magnetic field from the transformer.

Otherwise, if you have an AM radio--Having any 120/240 VAC wiring run near the night stand could cause the radio to hum/have interference sometimes (not necessarily because of the GT inverter--But just electrical noise running in the wiring from any/all AC appliances).

Bottom line #1: Would you have any hesitation installing this inverter 3 feet from the bed where you sleep?

That is a hard call... If you do not use an AM radio, do not sleep during the day (i.e., work nights), you probably would not know it is there (the tankless water heater is probably noisier).

However--Adding an additional 6 feet of wiring/conduit to push it a bit farther from your bed--You might want to do it (if possible). Just one less issue to worry about later (if it turns out to be a problem for some reason).

Question #2:
There is alternative location: a open-air (but covered) alcove/breezeway further down along the same (north) side of the house. It seems suitable for protecting the inverter and the battery from the elements.

On the plus side, that alcove location would remove it from the sensitive bedroom area.
The downside is that the alcove is further from the electric meter (about 25 feet)...but maybe benefits of that alcove location outweigh the costs?

"inverter and battery"??? What battery? This GT inverter does not use batteries (other than a small coin cell).

In general, if you have good air circulation, no "hot spots" (i.e., a corner of a room, mount near low ceiling, etc. where you can trap hot air)--Mounting the inverter out of direct sun and away from driving rain will be a good thing.

Regarding temperature specifcially... There are two types of thermal events that you avoid.

First is running in high ambient temperatures. Roughly, for every 10C above ~25C ambient, the life of the electronics is cut by 1/2 (i.e,.. running at 55C, then 1/2 * 1/2 * 1/2 = 1/8th the life). So keeping cool is a big help for long life (and going -10C cooler, you have 2x longer life).

The second, thermal cycling. Just the normal cycling of temperatures (from cold morning to hot mid-day sun + waste heat from electronics) can stress electrical connections and components. Having an area with stable temperatures can help extend life too (i.e., inside an insulated garage may be better than an outside wall that gets freezing weather through broiling summers).

Bottom line #2: How much do these distances (9ft. vs. 25ft.) matter?

Only major issue with wiring length. Some folks have the utility voltage that runs "high" (i.e., instead of 240 VAC nominal, closer to 255+ VAC nominal--Some utilities regulate voltage better than others, people at the end of the line--Such as a farm at the end of the dirt road, etc.). The GT inverters will shut down at ~260-264 VAC. So, the longer the wire run, the more voltage "rise) between the GT inverter, main panel, and utility transformer could be an issue.

If your AC mains run less than ~250 VAC, you probably will not have a problem. You can calculate the voltage drop using a voltage drop calculator, the current you want to run, size of wire, and the number of feet of wiring (one way run for this calculator).

http://www.calculator.net/voltage-drop-calculator.html

You can always run heavier cable to reduce voltage drop too (in the US, for every 3 AWG heavier cable, the voltage drop is cut by 1/2).

Question #3:
I am kind of interested in the Tesla home backup battery storage pack <http://www.solarcity.com/residential/energy-storage&gt; or something similar.
2a. If I add one of those storage units in the future, do I need to install it in close proximity to the inverter?
2b. If yes, then what are requirements for the battery pack (indoor/outdoor areas, minimum clearances, etc.)?

Bottom line #3: What do I need to keep in mind if I want to add a battery storage pack in the future?

Just to be clear--I believe the inverter your linked to above is a "pure" Grid Tied AC Inverter--It has no ability to run if the AC mains fails (no backup power). The standard GT inverters shut down if the AC Mains fail to prevent fire/shock hazard.

If you want back up power--This is pretty much a complete re-do of the inverter (using a Hybrid/Off Grid AC inverter + solar charge controller + battery bank + a new sub panel for backup AC power--i.e., run some of your AC currents like lighting, bedrooms, refrigerator, but not an electric oven, electric water heater, Air Conditioning, etc.).

Batteries do want to run from ~45F to 80F for long life and good performance. Too hot, batteries will not last as long. Too cold (sub freezing), the battery capacity is reduced (in cold weather), and can freeze in very cold weather/well discharged--Fully charged batteries not not freeze in most climates outside of the Arctic).

If you have plans to change over to battery backed "hybrid or off grid inverter" power... I would suggest you do the paper design now (for both GT and Hybrid/Off Grid inverters) so you can understand the tradeoffs/issues.

They use (for the most part) very different hardware and design considerations.

-Bill

On the wiring, you correct.

A metal plate, probably won't make much of a difference. You need a full Metal enclosure to make a major improvement. Not cheap or easy.

Install elsewhere if you are concerned.

Inverse square law. Move 4x further away and you reduce local emissions by a factor of 16x.

-Bill