Solar PV - Save Money & Shrink Carbon Footprint
 

We have been driving EV's for 3 1/2 years, and we are now using a heat pump for most of heating our house, as well. We got a solar PV system installed yesterday, and it should soon be generating a large amount electricity, to offset our use. The system is Sunpower 327 watt panels (about 20% efficient), and it is warranted for 25 years. The system will pay for itself in just over 5 years, with all the incentives, and in less than 10 years without them.

It is a 10kW system on the AC output, and the estimated annual output is just under 13MWh.

We have expensive electricity here in Massachusetts - we pay between 18¢ and 22¢ total per kWh (both generation and distribution costs); and we also have chosen to pay another 2.4¢ / kWh to support renewable generation. Even with these costs, driving our two EV's (Bolt EV and e-Golf) cost us only about 4.5¢ / mile.

Here's the roof panels, on our reconstructed roof (which is still in process):

http://img.photobucket.com/albums/v7...psitpjmfmc.jpg
http://img.photobucket.com/albums/v7...psdmpfxbxg.jpg

And the equipment in the basement:

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I am really looking forward to our reduced electric bill, and our reduced carbon footprint.

My power costs around 8 cents per kwh.
I plan on putting up solar panels as soon as I get my other house rented. It's about 90% done and I got someone beating down the door ready to move in.
I'm buying the system my self and installling it my self, since I do have an associates degree in applied science for wind and solar power generation and I am working on my journeyman electrician, I'm not letting some shady contractor make thousands of dollars off my install.
Put in about 4kw this year, then another 3 to 5 next year. Do 48v panels and 48v grid tie inverter.
I have heat pump now and hate it because it uses so much power, I have a new coal furnace to install before next winter, hopefully that will provide most of our heat next year.
Still looking to sell our 2000 VW bug, which is our spare car and buy a leaf and make it our primary car for all the little trips around town and drives to work.

I can't see your pictures, am I the only one?

Sorry about the pictures - I will upload them to this site, when I can.

Our generation costs are about 14¢ / kWh. Do you you also have distribution costs?

I am looking at a rocket mass stove with a biochar maker, for backup heat.

We are doing all the construction, and roofing, but we had the solar PV system installed. My old roof was an 8 pitch hip roof, and the shingles were failing. We stripped the 3 layers of shingles (about 10,000 pounds total) and removed all the old roof framing. We then used the rafters to double the attic floor joists, and then framed the new 12 pitch gable roof with 2x12's and LVL ridge and valleys. The new roof is a 50 year asphalt shingle.

I just lost a ton of welding related pictures on another site because they were 3rd party hosting them.

I have metal roofs.
The first building is an out building I was going to upgrade the main beam to a steel beam when I find an appropriate one at the scrap yard. Then double up some of each joists with my best salvaged 2x6 boards.
My worst case scenario is we get a bunch of heavy wet snow that drifts on the roof and hangs around the panels, then gets rained on.

I fixed the picture links!

Wow that's a lot of panels.
My roof is like a 2 pitch.

What's your voltage?
Are they approximately 30v panels seriesed up for really high DC voltage?
Since that seems to be the standard for grid tie setups.

I am going 48v for 2 reasons, when one cell gets blocked by a leaf, bird poop or a tumble weed it wont cut the entire strings output in half, just the 1 or 2 panels (if seriesed) that get shaded lose power. Only losing 100 or 200 watts instead of 1 or 2kw if not more.
Then as I add more panels and use less power as I change out appliences for propane or more efficient versions. Then some day production may exceed demand and then I might move in a 5 to 8 ton 48v forklift battery, get stand alone inverters, plus charge controllers and go off grid.

Grid-tied? Did you see this?

https://www.youtube.com/watch?v=NKWo-i-2pUA

Not to spoil it or anything, but...

It turns out that an installation that was signed off on by the installer, the inspector and Jack Rikard hisself was structured such that he was selling power to the grid at 2.4¢ per and buying it back from them at 12¢. ...Across a one and one-half inch shunt. ...For twelve years. He can't be making this up.

Also, where does the excess power go in a buffer overrun condition?

They pay consumption rate for solar power generation here, which is 7 cents per kwh.

In a buffer over run situation the inverter would over volt fault and shutdown. Standard safety feature for all UL approved grid tie inverters.

I think our panels are 35V. They each have a micro inverter. There are 3 AC strings that are current limited to 12 panels. My understanding is each panel is independent, so shading cuts out only the panels affected.

oil pan 4 — I was doing something else while i listened to it. Something about the inverter acting as a charger. I'd have to listen again.

Something about the inverter recognizing the number but not it's sign?

You may have been listening to something on hybrid inverters or all in one units.
All in one units combine the battery charge controller and inverter and some have 120 or 240v generator power inputs also built in to charge on cloudy days.
The last few years has seen a lot of new hybrid inverters on the market.
Hybrid inverters have all kinds of features now. The most common application is they can connect to a battery bank and be grid tied at the same time. More advanced setups act as a whole home or nearly whole home UPS.
Some offer a grid tie only setting and you can go back later and add batteries, some have to have batteries from the get go. Others will allow you to only consume your solar power and will prevent power from back feeding on to the grid, say if your power company charges you an extra 20 or 30 dollars per month to have a co-gen or net-meter and only wants to pay 1 or 2 cents per kwh and you opt to keep your stupid smart meter.
If you keep your dumb/stupid smart meter they only know how to count up, any current flow is counted as consumption, so if you push solar power on to the grid the dumb smart meter reads it as consumption.

:confused:

I was listening specifically to the video posted which speaks to what works and what doesn't, and what don't make no sense.

You might find it interesting?

I wasn't trying to bring your thread to a halt. Tell us about:

Rocket mass stoves are incredibly efficient - they can heat a building with 1/5th to 1/10th the wood that would be used by a typical wood stove. They are quite clean, as a result.

A biochar retort is similarly low-smoke and high efficiency, from intense heat. These also produce high quality charcoal, that can be used to sink carbon, and improve the soil.

I might have said tell us what we don't know. :)

Where would it be integrated into the structure? Was there an existing chimney or has it been heat pump only?

I am looking to use my existing brick chimney with a 7" stainless liner. I am leaning to what is easiest / possible. Masonry rocket mass stoves are tough to get permitted, I am led to understand.

I have been making batches of biochar in a 55 gallon barrel retort, which is great for getting rid of tree waste. The challenge with a retort inside the house is loading and unloading the pyrolysis chamber.

A workaround is to use metal containers to do the pyrolysis inside a good woodstove.

Paul Wheaton says that metal liners on heaters over four inches across on the inside are guaranteed to fail: https://www.youtube.com/watch?v=hLV6fQOPn_U&t=140s

The chimney is nowhere near the core of the stove and only runs at 150F.
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https://www.youtube.com/watch?v=CoOcsq12UkE
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We have had our solar PV system running for 30 days now, and it produced 1,150hWh in that time! With our two electric cars (Bolt EV and e-Golf) and heat pump, and all other utilities except our cook stove and clothes dryer, that is about 56% of what we used.

16% capacity factor already is amazing considering the poor weather we have been having.

Right - an average of 38.3kWh / day is okay, but not great. We have hit as much as 68kWh in one day.

The estimated annual total for our system was just shy of 13MWh. If we stay at the 38.3kWh / day average, that is almost 14MWh for the year.

Lovely looking house and location Neil.

Did you build the roof pitch to optimize power generation, or to shed snow?

I built the 12 pitch roof to get the most roof space I could reasonably get. It happens to be ideal for winter production, and yes snow shedding off is also important for winter production. My brother's system is on a 5 pitch, and that works better in the summer, but he has to clear snow with a long handled snow rake. Which is non-trivial work.

Can you share a "before" photo? Just curious to visualize what you described.

Wait, no solar hot water?

Probably better off installing more PV and running a hot water heat pump.
Depending on your homes lay out and where you live, some where cold like MA installing solar hot water can be a real pain because you have to run glycol and run these lines where you don't normally run water lines. That means you could be tearing out walls through 1 or 2 floors in a typical new England style home if your water heater is in the basement.
Actually I would only go through the trouble of thermal solar if I was going off grid and wanted to futlrther reduce my propane bill.

I have a heat pump water heater.

I was thinking more along the lines of Gary's $1000 solar water heater. The plumbing isn't extensive, but you do need space in the basement.

It beats turning the sun's heat energy into electricity, storing that, and then turning it back into heat again.

I will upload pictures of the old 8 pitch hip roof when I have access to them.

Solar heat collectors with vacuum tubes are pretty good. Maybe someday.

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Okay, I got the pictures of the old roof:

http://img.photobucket.com/albums/v7...psippdf1hk.jpg
http://img.photobucket.com/albums/v7...pss0sdzhto.jpg

Tomorrow will be 60 days of production from our solar panels, and it looks like the total will be about 2.36MWh. Which is pretty darn good! We could be as much as 14MWh for the year, if things keep up this way.

So far, this is over 70% of the electricity we use; which includes our 2 EV's.

I have switched our electricity supplier to a company called IGS Energy, that is 100% wind generated. This is saving 0.99¢/kWh from Eversource (our old supplier) - AND I have canceled a Mass Energy program that I was paying 2.2¢/kWh to get about 61% renewable.

So, in total we will save 3.19¢ / kWh that we draw from the grid, and we will only draw about 1/3rd of our electricity from the grid.

What's your average production per day compared to name plate?

We are averaging a tiny bit more than 40kWh / day.

The total capacity is 10.137kW - which is a rate; not a quantity.

I was wondering what your utilization is. Looks like you are makin about 1kwh per 250 watts of panel per day.I
Which is to be expected up north.
Around here I'm looking at more like 200 to 220 watts of panel to make 1kwh per day.

At 60 days of production from our 10.1kW solar array, we have a total of 2.386.1kWh, which was 70.7% of what we used. That's 39.77kWh / day average. (We had several cloudy days recently.)

We have also switched our grid supplier, and gone from about 61% renewable energy, to 100% wind renewable - and better yet - we are saving 3.19¢ / kWh!

We have two electric cars, and one gasoline one. The Scion xD sits in the driveway 6 days a week, usually. And our natural gas bill is tiny, as well - we cook and dry our clothes with natural gas. Next stove will be an induction unit, and hopefully the next clothes dryer is either a heat pump, or ultrasonic (if they produce them).

Everyone should use natural gas range and dryer, they use almost no electricity.

Most home energy is used to heat and cool it. We have a mini split heat pump (5 inside units, 1 outside), and with our current insulation and windows, we have to use the natural gas fired steam boiler when/if it gets below 15F for more than a day or two. To cool, we manage the windows, and use ceiling fans as much as we can, and then use the heat pump to cool when we have to.

You should look into induction stoves - they are just as controllable as a gas stove, and are much more efficient. The only caveat is you need to use steel / iron pans with the induction coils. The upside is the top of the stove stays cool - you can put a piece of paper between the stove and the pan.

As I understand it, ultrasonic clothes dryers would be very energy efficient - and they don't heat the clothes, so the clothes last longer.

When you say we are getting 250 watts / panel / day - that doesn't mean anything. Do you mean 250W<b>h</b> / panel / day? Which is not correct - we are getting 1.28kWh / panel / day. (39.77 / 31)

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A Love Affair with My Clothesline

We have a clothesline and we don't use it enough - but, it doesn't work at night, in the rain, or in the winter.