Any experience with North East facing solar panels in NJ/NY?

[AnonNJ]

Considering a couple of Powerwalls to deal with occasional 1-2 day post severe weather outages and the memory of Hurricane Sandy. We lose power a couple times a year due to tree limbs. When power goes out, I just want the fridge to keep running, some lights to work, charge cell phones/tablets and have the option to run laundry or central air or open the garage if needed. Right now I manage this through a couple UPS devices and a propane generator where I string extension cords all over the place.

It would make sense to allow off grid recharge, but solar panels will greatly detract from the beauty of my home on the West/SouthWest facing front side. The only way I can place solar is effectively NE facing on the back of my home. And due to facing being less than ideal, I would seek the smallest possible system just to trickle charge the Powerwalls. This is because the 30% incentive is pretty attractive.

Anyone done something similar? On a NE facing in the the NE of USA, what could a 1 or 2 KW sized system actually capture? Would I get some energy generation? Enough to be at all meaningful for replenishing powerwalls and justifying cost increase to obtain the 30% credit? Thanks!

 

[Instaurare]

Have you considered that there are flush mounted modules that really would not detract from the appearance? And also, in a few months the Tesla solar roof will most likely be available in your area, and that is something worth waiting for.

 

[ItsNotAboutTheMoney]

Get a small generator. It'll do the same job and be a lot cheaper.

Or you could just get a Powerwall and have it set for back-up.

 

[Sylvia Else]

or central air

My central air conditioner draws about 4kW, and would run down a Powerwall quite quickly. If you want air conditioning during blackouts, you'd best install a split-system to condition one room.

Also, is the central-air conditioner single phase? If not, you'd need a multi-phase inverter to run it during blackouts, which increases the cost. I don't know that the Powerwall even has such a capability yet.

 

[AnonNJ]

Thanks for the great thoughts!

Have you considered that there are flush mounted modules that really would not detract from the appearance? And also, in a few months the Tesla solar roof will most likely be available in your area, and that is something worth waiting for.

The flush mounts are acceptable to me in many cases. However, I have too many peaks in my roof. Aesthetically it is impossible on the sunny side. Wife has completely banned panels on front of house. Home was new construction recently so redoing the roof is unfortunately frivolous.

Get a small generator. It'll do the same job and be a lot cheaper.

Or you could just get a Powerwall and have it set for back-up.

Natural gas whole house generator installed in my area runs about $2k more than Powerwalls. So standalone powerwall is probably the best way if I'm going to sink the money and move away from portable generator.

My central air conditioner draws about 4kW, and would run down a Powerwall quite quickly. If you want air conditioning during blackouts, you'd best install a split-system to condition one room.

Also, is the central-air conditioner single phase? If not, you'd need a multi-phase inverter to run it during blackouts, which increases the cost. I don't know that the Powerwall even has such a capability yet.

I had not considered this. I do have multiple zones and could restrict to a lower draw situation, but I may run into the multi-phase issue. A/C is really not important. Laundry/basic lighting/hot water/furnace air moving, etc are more important for typical durations.


Still very interested if anyone has ever put panels on the dark side and what kind of power is possible to generate.

 

[Sylvia Else]

Still very interested if anyone has ever put panels on the dark side and what kind of power is possible to generate.

I did a simulation of the New Jersey area, based on a 30 degree roof angle, and facing exactly north-east. This suggests it would do reasonably well in summer, getting up to 70% of the rated maximum, but get very little in winter. This fits in with intuition, given that the sun rises somewhat towards the north in summer, and the days are long.

I don't think this makes sense for a backup solution. Indeed, I'm not sure that lithium ion batteries are the way to go. They are expensive, with their main benefit being that they're more tolerant of cycling that lead-acid batteries. But in a backup scenario, you're not intending to cycle them often anyway. Provided you have somewhere suitable for them to go, you might find a bank of lead-acid batteries paired with a good quality inverter-charger provided a much more economic answer, or, equivalently, a much greater run-time per dollar.

 

[NuShrike]

What about reverse-tilt table-mount on your NE side? They would face SW, be on the backside of the house, and shaded only by your own roof?

 

[cwied]

Also, is the central-air conditioner single phase? If not, you'd need a multi-phase inverter to run it during blackouts, which increases the cost. I don't know that the Powerwall even has such a capability yet.

As far as I know, we don't have three-phase power over here in residences. Instead we have 120/240 split-phase power. The US Powerwall inverter supplies both legs (and also supports 100% imbalance). I have two central AC units behind the gateway. Of course if I actually ran them during a power outage, the Powerwalls would not last long, but at least theoretically, the Powerwalls can support any appliance that's likely to be installed in a residence provided enough Powerwalls are installed to handle the size of the load. There is the issue of starting current for the AC compressor too, depending on how big it is.

 

[Dan123]

st possible system just to trickle charge the Powerwalls. This is because the 30% incentive is pretty attractive.

Anyone done something similar? On a NE facing in the the NE of USA, what could a 1 or 2 KW sized system actually capture? Would I get some energy generation? Enough to be at all meaningful for replenishing powerwalls and justifying cost increase to obtain the 30% credit? Thanks!

You can get a good estimate by going to PVWatts Calculator

You will need to know the pitch of your roof, and the orientation of your panels in degrees (0 is north, 90 is east).

I think a 2 KW system facing NE, may generate 4 KW per day on average. A little more in the summer, and probably close to nothing in the winter.

Installers generally charge more for systems that are less than 4KW, so you might as well go a little higher and install 4KW.

 

[AnonNJ]

You can get a good estimate by going to PVWatts Calculator

You will need to know the pitch of your roof, and the orientation of your panels in degrees (0 is north, 90 is east).

I think a 2 KW system facing NE, may generate 4 KW per day on average. A little more in the summer, and probably close to nothing in the winter.

Installers generally charge more for systems that are less than 4KW, so you might as well go a little higher and install 4KW.

Very interesting link. Thank you! Looks like on paper I'd do 8kw daily average. That is certainly enough to keep a fridge going and some basic lights.

Month Solar Radiation
( kWh / m2 / day )
AC Energy
( kWh )
Value
( $ )
January 0.97 94 14
February 1.70 151 23
March 2.70 269 40
April 3.81 351 52
May 4.86 455 68
June 5.40 471 70
July 5.35 469 70
August 4.37 387 58
September 3.13 279 41
October 1.92 181 27
November 1.08 95 14
December 0.79 74 11
Annual 3.01 3,276 $ 488

 

[eml2]

Remember to take 15% round trip loss by PW2 into your consideration.

 

[ItsNotAboutTheMoney]

Natural gas whole house generator installed in my area runs about $2k more than Powerwalls. So standalone powerwall is probably the best way if I'm going to sink the money and move away from portable generator.

If you're really just looking for emergency cover a Powerwall is overkill and it also has limited capacity.

7kW/8kW portable generators are $900-$1500, plus installation.

How much would your maximum load be?

My friends have a generator hooked up on a 50A circuit and it kept them going through a week-long outage last fall.