10kW Ground Mounted Solar Panel System

[hayden]

If you get any appreciable amount of snow where you are located, I would suggest looking seriously at seasonal tilting of the panels. They will shed the snow much better if tilted to about 65 deg off horizontal. And of course you will get better yield too. If you leave them with a 45 deg or so tilt, they could sit for a long time covered in snow. I see that around here on some of the big commercial installations. And don't forget to keep them high enough off the ground to stay above snow level, and above any piles of shed snow. The bottom edge of mine are about 5' off the ground.

 

[Oaktree]

Google has a tool to calculate the payback of a solar system. I ran their model for our place in Oregon and it said that solar would cost us $8k over 20 years- there's never a payback.

I would imagine the long stretches of overcast you get in the PNW would put quite a damper on solar production.

 

[Carl_NH]

I was inspired by this to go look at my actual production. I have a 10 kW system, trailing twelve months production is 12,000 kWh. So actually about 1200 hours equivalent a year. That's worth $3480 at current rates. I get 100% net metering at full retail rates so I get the full value.

And this is tax free income. If I were paying the electric bill I'd be paying with after-tax dollars.

We have 7.2KW (25 LG Neon 300W) panels on the garage (separate service entrance) since December 2014 and we just hit 77MW (average 7700KWH/Year) with net metering we over-generate but they pay us the current rate for excess power. Payments are taxable over $600 a year - they send us a 1099.

Our array was $3.65 a watt in 2014 installed $26K then tax credits and rebates of $13K and electricity at $.18 a KWH the ROI was 8.4 years.

Yes, it's "free money now" vs paying for the power.

 

[John_Mc]

A complete solar installation paying for itself in the northeast, in just a few years, would be amazing

My grid-tied system (no battery back-up) here in VT paid for itself in 8 years. I did save a bit by helping with some of the labor on the install.

 

[quicksandfarmer]

I would imagine the long stretches of overcast you get in the PNW would put quite a damper on solar production.

The term for how much sunlight you receive is "insolation." The National Renewable Energy Laboratory publishes an insolation map of the US (and world) at NSRDB

The unit they use for the map is average kWh/m2/day. I find a more useful measure is equivalent hours per year, because you can multiply that by the rated output of a panel to get kWh per year; multiply that by your electric cost to get dollars per year. It's helpful to know that panels are rated at a solar intensity of 1 kWh/m2, so one kWh/m2/day is equal to one hour per day. So if you take your average from the map and multiply by 365 you get expected hours per year.

The map shows Rhode Island in the 3.0-3.5 kWh/m2/day band. As I noted earlier, in the past 12 months I got the equivalent of 1200 hours of sunshine, which would mean an average of 3.28 kWh/m2/day. And solar pays for me, mostly due to high electric rates and generous net metering policies. The Pacific Northwest has about the same level of insolation, but my understanding is electricity is cheaper there so it might not pay to go solar.

Parts of the southwest have double the level of insolation I see.

 

[John_Mc]

The term for how much sunlight you receive is "insolation." The National Renewable Energy Laboratory publishes an insolation map of the US (and world) at NSRDB

The unit they use for the map is average kWh/m2/day. I find a more useful measure is equivalent hours per year, because you can multiply that by the rated output of a panel to get kWh per year; multiply that by your electric cost to get dollars per year. It's helpful to know that panels are rated at a solar intensity of 1 kWh/m2, so one kWh/m2/day is equal to one hour per day. So if you take your average from the map and multiply by 365 you get expected hours per year.

The map shows Rhode Island in the 3.0-3.5 kWh/m2/day band. As I noted earlier, in the past 12 months I got the equivalent of 1200 hours of sunshine, which would mean an average of 3.28 kWh/m2/day. And solar pays for me, mostly due to high electric rates and generous net metering policies. The Pacific Northwest has about the same level of insolation, but my understanding is electricity is cheaper there so it might not pay to go solar.

Parts of the southwest have double the level of insolation I see.

Or you could just use PVWatts to do the calculation for you:

PVWatts

Estimates the energy production and cost of energy of grid-connected photovoltaic (PV) energy systems throughout the world. It allows homeowners, small building owners, installers and manufacturers to easily develop estimates of the performance of potential PV installations

pvwatts.nrel.gov

 

[MAX-24-Dean]

I would imagine the long stretches of overcast you get in the PNW would put quite a damper on solar production.

West of the Casecade mountains, yes. Except for the an area in west puget sound that is in the weather shadow of the Olympic Mtns.
East of the Casecade mountains there are some locations that get 300 days of direct sun, enough to keep a solar system running without the need for a generator for off-grid systems.

 

[quicksandfarmer]

Or you could just use PVWatts to do the calculation for you:

PVWatts

Estimates the energy production and cost of energy of grid-connected photovoltaic (PV) energy systems throughout the world. It allows homeowners, small building owners, installers and manufacturers to easily develop estimates of the performance of potential PV installations

pvwatts.nrel.gov

Hmm. I did the calculation, and it gave me average daily insolation of 4.96 kWh/m2 and an annual equivalent of 1410 hours of sunshine. Those two number don't agree with each other and are quite a bit higher than what I'm actually seeing.

 

[Pettrix]

Here are the specs on the panels:

China 750 Watt Solar Panel Manufacturers Suppliers Factory - 750 Watt Solar Panel in Stock

We're well-known as one of the leading 750 watt solar panel manufacturers and suppliers in China. Please feel free to buy or wholesale high quality 750 watt solar panel in stock here from our factory. For price consultation, contact us.

www.jingsun-power.com

 

[DarkBlack]

Price wise, I am able to get 23 bifacial solar panels (750w) and the mounting brackets for $2k delivered from my Chinese contact. Panels have a 25 year warranty and are rated\tested

So bifacial panels will break more easily in hail than standard panels?

The outgoing administration just recently added tariffs back on biracial panels. They were exempted for a while. Might explain the good pricing.

I saw a video from Germany, where they experimented, and found vertical mounting actually gave the best daily output with biracial panels.
The drop in efficiency at peak hours was more than compensated by early morning and evenings.
It also eliminated snow loads.