[Russell Graves] lives in Idaho and recently connected his solar installation to the grid, which meant adhering to regulatory requirements for both the National Electric Code (NEC) as well as complying with the local power company’s own regulations. His blog post is an interesting look at the whole regulatory process and experience, and is of interest to anyone curious about running their own solar farm, whether they have plans to connect it to the grid or not.
The power company has a very different set of priorities from the NEC, and part of [Russell]’s experience was in having to meet requirements that weren’t documented in the expected places, so study of the materials didn’t cut it. In particular, the power company needed the system to have disconnects with conductors that visually move out of position when disconnected. [Russell] was using NEC-compliant circuit breakers that met NEC code, but they didn’t meet the power company requirement for conductors that can be visually confirmed as being physically disconnected. Facing a deadline, [Russell] managed to finesse a compliant system that was approved, and everything got signed off just as winter hit.
How well does his solar farm work out? Sometimes the panels produce a lot of power, sometimes nearly nothing, but it has been up and running for all of winter and into spring. Over the winter, [Russell] pulled a total of 3.1 MWh from the grid, mainly because his home is heated with electric power. But once spring hit, he started pushing considerably more into the grid than he was pulling; on some days his setup produces around 95 kWh, of which about 70 kWh gets exported.
[Russell] didn’t go straight to setting up his own modest solar farm; we saw how he began by making his own ideal of a perfect off-grid office shed that ran on solar power, but it has certainly evolved since then and we’re delighted to see that he’s been documenting every bit of the journey.
25 thoughts on “The Regulatory Side Of Rolling Your Own Moderate Solar Farm”
A good friend of mine went through the visible disconnect when he plumbed is generator up to his house, even though the generator had an approved transfer switch. In the end the power company allowed him to put up a second meter box that they installed a shunt they could pull out in. If I recall his go round with the utility the visible disconnect needs to be on the outside of the house where they can access it in case they need to remove your feed from their grid.
Looks to me like this is a rather rural site, it may be there are some water pumping stations, perhaps a fairly large work shop. Idaho can still get pretty hot in the summer in the south part and lower elevations which this also appears to be. A welder can draw a large amount of power and they are usually left running for a considerable time while in use. Wood shops can be a big drain too. Since it is mentioned all electric, a shop may also be electrically heated. I set a system up for a small solar heating system assembly plant some years ago that also incorporated a 2.4kw wind turbine along with the 4kw solar array which had another 3kw added some years later. Before the system was completed which was in the late fall IIRC the electric bill would be around $200 a month, a low bill considering the building was 30×70 and heated with a wood stove. After both generation systems were connected, the bill dropped to around $25/month which was mostly the service connection fee per month. During high production periods, since it was also a dual meter system, we simply gained credits for high usage/ offset the monthly/annual bill after a baseline was established which took the better part of a full year. The utility Co. wanted the system monitored as it was the first system connected to the local provider in the area and they had no experience with such systems as yet. I know at that time the NEC hadn’t established a full set of guide rules for such systems and that is no longer the case. A lot has changed over the last 10 years.
“”some days his setup produces around 95 kWh, of which about 70 kWh gets exported””
I didn’t read anything about a battery system, so when the sun is shining he’s still using 25KWh of power, that’s during daylight hours only, is he running a bitcoin farm as well ?
Indeed. Just checked and our daily use is about 2-3 KWh while producing around 12 during summer. Looks like a poorly insulated house with the AC blasting all day long.
I think you’ve got an error in your math. At 2-3KWh per DAY, that’s about $12 per MONTH in electricity (using east coast rates $0.13/KWh). I suspect you mean your house averages 2-3KW per hour which would be in line with 25KWh/day). Unless you’re talking net usage instead of gross in which case: insufficient information for reasonable answer.
2-3 kWh per day is around 100 Watt average. That’s fridge + lights only territory.
Even my city flat needs 4 kWh a day, and that’s fridge + lights + computer and electric stove. If I had electric heating, hot water, and AC as well that would easily go up. A single hot shower takes like 3-5 kWh.
Nothing unusual about 25kwh per day of consumption, a bit high but you don’t even need AC for this ballpark. A pool for example is around 10/20kWh per day due to pump filtration alone.
Not even high. An electric-only household would use around 20-25,000 kWh a year, or easily 50 kWh per day. US average household energy consumption is 77 million BtU or 22,566 kWh per year.
The trick is that so many solar households use gas for the bulk of their actual energy demand, like heating and cooking, because it’s so much cheaper. 58% of household energy in 2015 came from gas (Source: EIA). When you translate residential gas prices to electricity prices, a kWh of heat from gas is around 6-7 cents.
Gas is definitely a problem in the UK.. Don’t get me wrong its a great fuel source, and certainly should have its uses, but the whole trying to go green isn’t helped by pumping gas everywhere and having lots of folks choose to use for everything, because its almost free in comparison to electric…
That said its very possible to run a solar household without gas, or with very little gas – that last one describes here very well – gas is pretty much only used for hot water, there is central heating, but its almost never on…
Or grow houses.
back in 2006 i memorized the rule of thumb that a house draws about 1kW on average. that’s 24kWh per day, so not far off at all. in practice, i have a 700sqft house, no A/C, gas heat in the winter, and of course LED light bulbs and so on, so these days my house is about half that, 500W average. but a bigger house with any sort of A/C or what-not would blow way past 1kW average.
(my system under discussion here)
Are you confusing kW and kWh? One is power, one is energy, and they’re not interchangeable units. It sounds like you’re confusing them.
A kWh is one kW, for one hour. Running a 1kW load, for 24h, would be 24kWh in a day. Running 500W for 24h would be 12kWh, etc.
My system produces 95-100 kWh in a day, but since we currently have very long solar days (currently about 7AM to 9PM of useful production), this works out to producing about 7kW, averaged through the day. I’ve included the production curves in my post, so you can see the details from the different arrays. Peak production at solar noon is in the 10kW range,
The house typically uses 20-40 kWh in a day, which is averaging 1-2 kW, sustained. It varies throughout the day, but overnight idle is around 400-500W, with more use during the day. We also have a Chevy Volt that plugs in and provides most of our transport miles, so that adds some load to the house (about 10kWh if we’ve driven it, most of the trips into town and back use the bulk of the battery range, which was the reason we have it – common trips on battery, longer trips on gas).
The system is overproducing the PVWatts estimates by about 15-20% for some reason (I believe part of it might be due to how well cooled the panels are, being on open frames instead of a roof), but we’re not using 25kW sustained on the house, nor is the system producing 95kW. Those are daily uses, in kWh.
For what it’s worth, my house consumes 10kWh/day winter, 9kWh/day summer, when central heating pump is off. 30 miles north of London, UK.
I can tell you 25kw is low, summer in Phoenix yesterday 117 f we ran 82 kw since mid may average around 55 kw
Yeah… smelting aluminium sure can add up
How do you feel about the fire department and the public library? Food inspection? etc.
None are necessary.
Volunteer fire departments or privately run.
Amazon. I’m guessing the MILLIONS if not billions spent each year to warehouse millions of books, magazines, and other materials that seldom circulate could go to reducing taxes so I can buy the books I want to read and the sell or give them to someone else.
If I buy food from a store that makes me sick, I just don’t shop there anymore. I reject your premise that food suppliers are in business to kill or otherwise harm consumers. An unregulated Internet would allow rapid dissemination of information about food safety and quality.
If not for the government funding development of the internet to begin with, you’d be posting this on AOL or CompuServe forums right now. There would not be a public shared internet because private companies each wanted control of their users’ online experience, and that’s how it would’ve remained to this day.
Do you think you’d be able to buy an IPhone, Android or any other non-Bell telephone to connect to the Bell Telephone network which is what would still be in operation today if not for government regulation? You have absolutely no clue what you’re talking about and need to learn your history before speaking like you do.
depends on what your problem is! if you value the ability to sell power to the grid, then government is a huge part of solving that problem. if you value the ability to receive grid power overnight, again, government to the rescue. if you value the ability for the power company to send guys to work on your lines during disasters and upgrades, this visible disconnect rule is a huge win for you.
but if all you care about is the things you are thinking about right now — today’s project — and you are willing to declare that every desirable element of the status quo is inevitable and unworthy of consideration, decreed by god and not government, then yeah, government just gets in the way.
i’m just trying to imagine any better example of government regulation helping you out than our heavily-regulated power grid with net metering provisions, and i’m coming up blank. government gives some Ws and some Ls but by and large US electricity service is a fantastic example of something of value we get from government. not that there aren’t mistakes and corruption, it’s just that you don’t look very hard to see that by and large it works really well.
How did civilization happen without the massively intrusive government we have today?
Read up on a political philosophy called Voluntarism or something like that.
Let’s start there and create a minimally intrusive government.
If I have my own power source and am willing to take responsibility for the consequences of it failure, I don’t need government.
And if I choose to buy power from one of 3 or 4 private utilities supplying my home, I don’t need government.
1. You get the government that you do or do not vote for.
2. You get the regulations that the citizens allow to be promulgated.
3. You get the society that you grow.
The obstacle to solutions is the citizen and their resultant culture. Hence people are the problem. So all ‘obstacles’ will be remove one we get rid of people.
I’ll grant that.
Though at this point in time governments like corporations seem to be “people” with lives of their own. What was that Supreme Court decision?
“Over the winter, [Russell] pulled a total of 3.1 MWh from the grid, mainly because his home is heated with electric power. But once spring hit, he started pushing considerably more into the grid than he was pulling”
And there is the problem with solar in a nutshell.
In the summer you dump so much on the grid that it needs to bleed the excess off into the atmosphere as more heat while in winter a reliable coal plant is chugging along to provide you with some warmth.
Electricity is only useful when supply and demand are in balance. To store your excess energy for later leaner times it is a lot greener to convert CO2 and water into a hydrocarbon which remains liquid at atmospheric temperatures and pressures.
“To store your etc…”
Got a specific method in mind for doing this?
I’m not sure that excess solar production is a problem in very many places.
(Contra: https://hackaday.com/2021/05/10/south-australia-vs-too-much-home-solar/ and those couple days in 2019 where electricity prices went negative in Germany. But those are exceptions, not the rule.)
Indeed in the USA, electrical consumption goes up dramatically in the summer b/c of air conditioning, and that mostly during the day. For that load, anyway, solar is a nearly perfect match.
Too much non-polluting energy production would be a lovely problem for the world to have.
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