Knowledge Help

[capertrj]

Hello all, first time poster, hoping to get some help! Live in southern maine with residential rate of $0.204/kWhr (net metering here). Recently had heat pumps (6 tons) installed as primary HVAC with oil backup. I got lucky with a F150 Lightning reservation and expect delivery any day (ive been saying every day for a month now). Commute is about 110 miles total 4-5 days a week (mix of 65% highway/35% residential). I figure a conservative estimate would be 2 miles/kWh which would be ~50 kWh a day. This commute isn't long term just another year or two and will reduce significantly. Please see below for more details.

Recently got estimates from two of the major installers in the area for a 10kW array which should be near annual usage. Prices are before 30% tax credit. Panels take up same area of roofing. This is a grid tied system with no battery back up. The lightning will be hooked up to manual transfer switch already installed for power outages.

First: 10.29 kW array
Silfab 490 Watt (21 panels) - 20.9% efficiency
SolarEdge SE10000 Inverter with SolarEdge DC optimizers
Price ~ 32k

Second: 10 kW array
Q Cell 400 Watt Q.Peak Duo G10+ (25 panels) - 20.4% efficiency
SolarEdge 7.6kW HD-Wave Inverter w/ revenue grade monitoring
25 SolarEdge S440 DC optimizer
Price ~ 35k

Both have 25 year warranties but the Silfab has a 30 year power performance guarantee of 82.6% at end of 30th year. It is nice as both are manufactured in US or Canada. Silfab has a slight advantage in power with a lower cost and long warranty.

Does anyone have experience with Silfab or Q Cell? Any recommendations or comments in general? It seems quite a few have solar on here and just wanted to see overall opinions as this is a pretty big investment.

I am active military and will move soon but this will be my "retirement" house. I feel like its best to do this now than later with increasing prices. The issue is if I go greater than 10 kW then it stretches into another section of the house which isnt "smooth". The other areas are down a stretch and farther down so could incease cost.

Thank you all!

[organic farmer]

I live in Southern Maine too, about 20 miles North of Bangor. Only another 40 miles to the North-South halfway point.

In 2015 I got quotes for installing net-metering. One of our neighbors did it. We just went with off-grid solar instead, a lot lower priced. But he did the more expensive grid-tied net-metering gig. As it turned out though, it really depends on how frequently your grid goes down.

Here the grid goes dark about twice a month, on average. In the past 17 years, we have never recorded any month without a power outage.

Net metering systems are not allowed to produce power when the grid is down. So your house goes dark, too.

[solarix]

Silfab is probably USA made, Q-cells was a German brand but was bought by Hanwa of China and now has a facility in Georgia. Both are good brands - you might check on where these units are coming from.

[J.P.M.]

Capertrj:

Congrads on upcoming final clearing of post. Best pre-wishes for a successful transition to what reads like upcoming retirement to civilian life.

Ques./Comments:

1.) Any local jurisdictions/building dept. regs./SOPs to clear ?
2.) How much of PV will be for the F150 load alone ? How much for house electrical load ? Get all loads you want the PV system to carry before you finalize the array size and design.
3.) Do you plan additional backup (generator) ?
4.) The F150 may well serve as battery backup but I'm not sure I'd hold my breath for delivery of the vehicle.

On the PV:
5.) If you have not done so already, consider downloading (a free PDF) of: "Solar Power Your Home for Dummies". It's a bit dated but if you are a solar neophyte, it's a good source of information your mother never told you about PV. Knowledge is power.
6.) Also if you have not done so already, investigate something called PVWatts. It's a user friendly program from NREL that will do preliminary residential PV design. Read all the help screens a couple of times and then do a few runs. Use the result of item 2 above for sizing estimates. Come back here with questions your results generate.
What will be the array's zip code ? Preliminary array orientation - array tilt and array azimuth ? Any array shading ?
7.) If you have building permits/local jurisdictional requirements, one of them may that you don't an entire roof with panels for several reasons. While that may seem like a PITA, it may be an advantage. See # 8 below.
8.) PV arrays will not clean themselves of snow. If you plan year-round array operation, consider how you will keep PV panels operating in winter. A fully covered roof is mostly impossible to clear of snow let alone service. Think situational awareness. Also, depending on availability and suitability of land, a ground mounted array can make life a whole lot easier, but at added cost.
9.) Beyond some basic level of quality, PV panels are pretty much a commodity these days. With that in mind, it's much more important to use quality vendors, particularly with the electronics, and especially with SolarEdge stuff. This forum seems to have more comments about SolarEdge problems than ringing endorsements.
10.) I'm ignorant of the per STC watt prices for PV systems in ME. You may in the wheelhouse on price, but regardless of what peddlers will tell you, prices are always negotiable. Just don't squeeze them too hard. They can screw you in ways you'll never know. The best quality and best value systems come from user knowledge and tough but fair negotiations on design as well as price.
11.) In the same location and orientation, well designed, installed and maintained systems of reasonable quality will all have about the same annual output per installed STC kW. So, as per #9 above, most bang for the buck and the best shot at the best probability for a trouble free system comes down to vendor quality and your negotiating skills.

Get the book, do the PVWatts self-training and then holler back with comments/questions/suggestions.

Welcome to the neighborhood and the forum of few(er) illusions.

[peakbagger]

I assume one of the firms is Revision Energy?. They are employee owned and have been around for awhile. They do a lot of volume so that means they get good bulk pricing, and their employees are going to be bit more motivated.

It is highly unlikely that any solar panel manufacturer will be around in 10 years let alone 30, Its just the nature of the industry.Usually issues with panels show up fairly quickly. The only long term guarantees worth anything are third party backed up by insurance companies and at best you will get a check. With that in mind I strongly urge you to buy a couple of spare panels and store them in attic. S**t happens and the odds of being able to replace a panel with the same model and color is slim to none.

It will snow in southern Maine and dependent on how close to the coast you are, you will get snow changing to rain and then cold (typical northeaster). The snow will stick and contrary to what the salesman say, the array may not melt off for several days. When the snow does slide off, it comes down in an avalanche. Anything in the line of fire on the ground will be damaged including people. Make sure that you do not have any exit doors or walkways below the array that are in the line of fire. When it lets loose after a big snowstorm, its going to set up like concrete. If its in the way, deal with it sooner than later.

I use a plastic snow rake to rake my arrays. Some use rakes with foam on the edges to avoid damaging surfaces coatings on the panels. Mine do not appear to have any so I just use a standard plastic roof rake.

With 10 KW you probably will have a main panel upgrade or a line side tap installed. If is a main panel upgrade install a good quality Surge Protection Device on the panel that has a low enough clamp voltage to make a difference. The Midnight Solar SPDs have a good rep. Some of the name brand Home Cheapo devices have less good rep, they may stop an electrical fire but still allow enough voltage to pass to fry electronics. I had inverter cooked with a name brand one. If going line side tap have a SPD mounted at the tap location. Places that have frequent outages are prone to surges from the utility and when you get one they are very random at the damage that can occur.

[bcroe]

I expect snow and cold will happen there, 6 tons should do quite a lot
depending on the house heat load. Here the heat pumps for that are
selected specifically for ability to function well below 0F. And mounted
high enough that snow will not build up and block them.

Panels ground mounted also should be high enough to be clear of
snow buildup, read the sticky thread Snow Tolerant PV Mounting

Roof mount works but gives up optimum positioning and much easier
arrangement to keep cleared of snow. good luck, Bruce Roe

[capertrj]

I expect snow and cold will happen there, 6 tons should do quite a lot
depending on the house heat load. Here the heat pumps for that are
selected specifically for ability to function well below 0F. And mounted
high enough that snow will not build up and block them.

Panels ground mounted also should be high enough to be clear of
snow buildup, read the sticky thread Snow Tolerant PV Mounting

Roof mount works but gives up optimum positioning and much easier
arrangement to keep cleared of snow. good luck, Bruce Roe

They are arctic models to operate at -17F. They are both shielded from snow cover. If it gets really cold, I still have the oil burner for heat/hot water.

[bcroe]

They are arctic models to operate at -17F. They are both shielded from snow cover. If it gets really cold, I still have the oil burner for heat/hot water.

It would be good to hear your report on performance after a
winter, and some pictures of the arrangements. Here is the
heat pump that keeps my shop building in a comfrotable range
all year around. Besides being 40 in above the ground, it
needs shielding from very heavy snow slides off the second
story, slippery metal roof. Bruce Roe
15RLS3H10.JPG

[peakbagger]

I have a friend in Yarmouth Me who makes a living selling backup heat to folks who bought into cold climate heat pumps being adequate for Maine winter

Good you have a backup

[Will792]

They are arctic models to operate at -17F. They are both shielded from snow cover. If it gets really cold, I still have the oil burner for heat/hot water.

I have been using heat pumps with oil boiler as backup for 2 years and the problem is that heating oil does not always work reliably if it is used occasionally. A few times I discovered that burner (Buderus boiler with Riello burner) fails to fire up just days before outside temperature was forecasted to drop below 13F, cutoff for my heat pumps. Unfortunately I cannot get NG line so propane is the only alternative to heating oil.

[peakbagger]

Sorry to the OP for the thread drift

There is something wrong with your oil boiler or your installation. I use oil as an automatic backup to my wood boiler and it may not run for months and starts reliably. I have heard of some issues with loss of prime on the oil pump where a house was converted from an underfloor oil supply pipe to an overhead line with installing a Tiger Loop device adjacent to the burner. In theory a boiler can pull a suction without one but its far more likely to have non start.

The other issue is if you have an outdoor tank and not running #1 i(more expensive) instead of #2 fuel oil. #1 has a lower pour point than #2 but lower btu content and higher cost. #2 in an outdoor tank will burn when its relatively warm but gell at some point when the temps drop. Some folks with outdoor tanks try to use the cheaper #2 and then switching to #1 when it gets cold but the, having any trace of #2 in the tank can cause gelling issues with #1. There are commercially available additives that can help this issue but the problem is getting it mixed in with the oil. Ideally it gets added prior to tank fill. Some folks enclose the tanks and put a heater in the enclosure.

[Will792]

Silfab is probably USA made, Q-cells was a German brand but was bought by Hanwa of China and now has a facility in Georgia. Both are good brands - you might check on where these units are coming from.

Small correction. Hanwha is South Korean company.