Building my own solar power system
medium.com437 points by JKCalhoun 6 days ago
437 points by JKCalhoun 6 days ago
I’ve been running a solar microgrid on my coffee farm for the last 7years. We started with a few golf cart batteries and 4 panels, these days we’re powering 4 houses, 7 cabins, water extraction, treatment, and RO processing, campus-wide fiber network and switches, path lighting, security systems, and a small server rack.
We’re running 6 inverters on our primary system in a three phase configuration, 35kw of panels and 160kwh of lithium iron batteries. About to add an additional 20kw of panels and a test bank of LiTo cells.
Our panels are a distributed set of rooftop mounted panels on various buildings, which also serves to shade the rooftops reducing cooling loads.
We still have to run a generator to supplement charging on dark overcast days, but it’s typically about 100 hours a year. Hooping to get that running on biomass eventually.
It’s strange to me that people in rural areas pay for electricity. It makes no economic sense, at least here in the Caribbean.
> It’s strange to me that people in rural areas pay for electricity. It makes no economic sense, at least here in the Caribbean.
This comment was very confusing until I read the second sentence. Electricity prices in the Caribbean are very high, and I can only imagine that rural areas are even worse.
Where I’m at in the United States a typical electric rate is around $0.10/kWh. Paying that nominal amount and avoiding the need to service additional equipment and deal with backup generators is an easy decision.
You’re in a good part of the country for grid power. I’m in Georgia where the typical rate is about 14 cents but summer rates are more like 18. Summer rates aren’t captured in this EIA chart but you can see the whole country. With summer rates and high energy use for cooling and dehumidification it’s a 7-8 year payback for a 13kW DC/10kW AC system.
https://www.eia.gov/electricity/monthly/epm_table_grapher.ph...
I’m jealous. Where I live in California the off peak rate is $0.32/kWh and peak rates are $0.58/kWh.
Rural area power co-op member here - flat rate 24/7 for residential is .13/kWh. Businesses/farms can get down to .10/kWh if they qualify.
They proposed to update it to .15 so they could trim trees around the lines a little better, but it got denied by the co-op members as unnecessary.
> They proposed to update it to .15 so they could trim trees around the lines a little better, but it got denied by the co-op members as unnecessary.
Pge felt the same way and it did t turn out so well for them. I hope your coop is never found to be at fault for the next record breaking fire…
So the increase was to buy spray equipment to attach to a helicopter. And a helicopter. One of the co-op ex-board members' son recently moved back to the area and had his license. . . It was a shameless cash grab by that family and was rightfully voted down by a wild majority of the co-op members. Every member of the board was replaced within 2 years of them proposing the increase as well.
They currently keep all the lines clear via bucket trucks, and when they spray, they use ATV's and trucks. It takes most of June to spray all the lines, but they get it done easily.
The actual physical infrastructure has been replaced almost entirely in the last 10 years through federal and/or state grants in combination with income from power charges.
Also, these are just fundamentally different entities. PGE is a private entity that operates for a profit. Our power company is a co-op owned and run by its members. If they have any profit at the end of the year (once infrastructure improvements and safety net investments are paid for), the money gets paid directly back to the co-op members. It's a WILDLY different incentive structure.
Not every place is built in a dry forest which traditionally burned regularly but the current infrastructure is built around never burning. The only risk in, say, Michigan, is the power going out at inopportune times.
If that's considered high, I'm just not going to say what it costs in the Caribbean.
At least where I was.
I'm in the Bay Area - Off peak is 0.44 and peak is 0.48
Separately for "clean power", Off peak is 0.13 and peak is 0.17
So that's a combined 0.57 and 0.65
$0.08/kWh here for central Illinois
Taxes and supply charges are what take it from cheap to expensive in Illinois.
Doesn’t that sort of rate make the payoff for a solar system install just a few years?
Yeah - even with PGE trying their best to screw over solar customers in the last few years, I figure we've at least gotten our money back in ~15 years of owning a ~4KW system. Something like 75 MW generated in that time, assuming the inverter is more-or-less correct. At this point, doesn't make any sense anymore, since they only credit you like $0.1 and charge you $0.6 (I haven't looked too closely at it) - you'd have to generate 5-10x your consumption to mostly offset it.
We bought ours in '10 to offset high AC use in the summer - we were paying $1000-1500 a month for 2-4 months in the summer. The first few years, our "year-end" balance was < $1K (we just paid minimum payments the rest of the year), so I figure we easily saved $2-3K/year in those early years, and after the incentives in those days, we paid ~$14K, so maybe 7 years to pay it off. Our year-end balance was more like $3K the last time, and I think we're still producing 80-90% the same power, but PGE keeps changing the plans around. At this point, I'm interested in upgrading our cells from 300W to 450W, but I'd only do that with a battery system that also stores energy so that we could go more or less entirely off-grid. But probably need a new roof first..
> I’m jealous. Where I live in California the off peak rate is $0.32/kWh and peak rates are $0.58/kWh.
My California rates are .50/63 off/on peak
"Jealous" is not the term I'd use...
In Quebec, I'm paying $0.069/kWh or USD $0.05/kWh (hydroelectric, so already green), so it's hard to make a case for solar.
> hydroelectric, so already green
Not so fast. Zero emissions, yeah. But they have damaged the habitat for some bird species.
Feral cats kill 2 billion birds a year, FYI the green energy kills birds thing is a right wing talking point designed to distract and delay. All human activity kills some nominal number of birds
Indeed. They care about the environment when pretending to do so lets them fight against things which are actually good for the environment and bad for the fossil fuel industry.
Whataboutism arguments kill 2 million discussions per year by avoiding refutation of the central point.
I'm in the Canadian prairies and we pay a similar electric rate. It's funny though...
> avoiding the need to service additional equipment and deal with backup generators is an easy decision.
We've got a house in a very small town (pop. 100) and there are solar panels on a ton of the houses there. I've asked a few people about it and it's 100% for grid redundancy. Sure, they save a bit of money on their power bill, but they're basically using the panels and batteries as an alternative to a backup generator. Winters are quite cold here and having enough power to run the natural-gas-fired furnace and a few light bulbs is a huge win when the power inevitably goes out. Lots of people have small generators kicking around too (like the Honda EU2200 that RV folks love) but the solar install has seriously cut down on the need for those.
I’m in a mountain town in BC Canada and pay $0.13/kWh. My 7.8kW solar system cost me $0 out of pocket after incentives and an interest free loan. It’s making ~$1000 per year of electricity, so we’ll just put that onto the loan for the next 8 years instead of paying it to the power company. Then for ~25 years after that it will make me $1000/year. Free money.
(The price of electricity is already pre-approved to increase 5% a year, so actually my savings will be more every year than the year before)
Solar can be worth it even when power is cheap.
$0.10 kwh is low for most of the US. Can I guess.... Western state or PNW?
Over here in PA I pay $0.095, so nine and a half cents, per KWh for electric supply, but then I pay that same amount for transmission, so it's functionally 19 cents per KWh, but maybe the person you're replying to isn't counting transmission fees?
Similar here in Maine under CMP. Something like 12.5 cents/Kwh, but with the delivery aspect factored in it's basically 28 cents/Kwh.
I always assume when people on here are talking their 'rates', that they are usually NOT factoring in the delivery fee unless stated.
But maybe some places are just really THAT cheap.
I pay 11.6 cents per kilowatt hour inclusive of everything (taxes too). My household used 647 kilowatt hours in April and the bill for the month was $75.02. The per-unit charge neglecting taxes and delivery is only 7.4 cents. This is in Washington state.
I don't know why anyone would not include the "delivery" fee, I think it really is that cheap in many places in the US.
Here in NYC the "supply" charge is much less than half of the total bill. If I add up all the fees and surcharges and taxes etc, the total ends up around 35 cents / KWh, which I thought was rather high until I heard about California ...
I pay around 10 cents per kWh in the southern US; we have a nearby nuclear plant. We do have a base fee just for the meter, but no separate transmission fee. My in-laws in Texas have an open market for generation but pay transmission separately.
why would you not include the transmission? residential customers just pay one bill and that's including the lines, maintenance.
In western states such as Oregon, Washington, it is actually 0.12KWH including transmission.
This is truly interesting and inspiring.
Is there any documentation of your solar microgrid systems for learning purposes? Or better can anyone visit your farm for learning the microgrid systems?
I just found these article back in 2017 and 2022 on microgrid installation in the Caribbean and they looks like promising off-grid solutions for tropical islands [1],[2].
[1] Why Solar Microgrids May Fall Short in Replacing the Caribbean’s Devastated Power Systems (2017):
https://spectrum.ieee.org/should-a-devastated-caribbean-leap...
[2] As rich nations haggle over climate solutions, storm-ravaged Caribbean is taking matters into its own hands (2022):
https://edition.cnn.com/2022/11/15/world/caribbean-solar-pow...
How has your experience been with the lithium-titanium-oxide batteries? Everything I read makes it sound like the optimal solution for safety and long life, but it doesn't seem like they have displaced other battery chemistries very much.
What is your recovery plan in the event of a hurricane?
I'm not fond of high electric rates, but in addition to generation those rates amortize and distribute the cost of storm recovery. A home or business with grid-tied solar pays interconnect fees for the option to get paid back a little for excess generation, and the option to decide to switch back to 100% grid power if a storm damages the on-site panels.
> those rates amortize and distribute the cost of storm recovery
Not exactly when it is a farm out there away from a town.
My experience is from a different era (90s) and a different kind of farm, but I spent a bunch of summers in one, which had power outages whenever the monsoons picked up.
The trouble was that there was a single line feeding the farm from about 6km away, so if that went down a single farmowner complained - the rate payers who were in a denser urban area always got priority, because there were 600+ people who shared a transformer.
The generator ran a lot when winds knocked power out, but the generator only ran when there was a big power need like running the well pumps or one of the winnowing mills. Even the winnower had pedals, because work doesn't stop.
Every bathroom had a light with a 30 minute battery in it, which came on when the power went out - I guess if they had LEDs those same batteries would be 6 hour lights.
They would have killed for solar + storage, because shipping fuel in for the generator was one of those annoying things you had to keep doing over and over again.
>The trouble was that there was a single line feeding the farm from about 6km away, so if that went down a single farmowner complained - the rate payers who were in a denser urban area always got priority, because there were 600+ people who shared a transformer.
The urban rate payers also subsidize the rural ones, so it makes sense that they'd be front of the line.
I would have thought an isolated farm would have had propane on site - likely more than one tank.
I don’t worry about outages much in my current home because the main line to ~1000 houses goes right past me, and I’m fed straight from it. If I’m out, it’s a very high priority line. Worst ever was about two days. It helps that our worst storms are usually in spring, so weather is mild.
After a hurricane, the plan might be to help neighbors charge their phones, or sell electricity to telcos to power their networks switches and cell towers.
I think I am much less remote than the poster, and I can easily lose power for a week or more after a winter storm. Considering that they already have generators on site that can manage the full load, they probably have much better up time than the utility electricity provider.
All underground infrastructure or in concrete utility huts. Powerplant is concrete, no flooding issues due to excellent drainage of the area.
We can run on generator to charge the batteries for about 2 weeks on the fuel we keep. Other than that, we rebuild what isn’t broken and later buy more panels. Most of our mounts should be good to about 150mph, but trees also fly so?
Good news is we can buy panels here about $120 for a 500 watt panel.
Also we have some geographic protection from the full brunt of a storm , as we are in a mountainous eddy zone that typically sees about 30 percent of the coastal and mountaintop wind speed when a cyclone passes nearby as they frequently do.
For the US, the entire user base helps subsidize rural customers. I have recently had the thought that I'm curious how this subsidy compares to the price of creating local micro-grids for rural communities. Especially in places like California where it is long distance power lines running to rural communities that have started several major fires.
I don't have the skill to do it myself, but I'd love to see an analysis of whether it would make more sense at this point to do solar/wind + batteries and backup generators for at least the smallest and most remote communities.
Australia has just completed 5 years of feasibility studies on this:
https://www.dcceew.gov.au/energy/programs/regional-remote-co...
and moved to the pilot phase:
https://arena.gov.au/funding/rmp/
A review of some of the feasability studies carried out in phase one:
https://www.sciencedirect.com/science/article/pii/S221462962...
The Scottish island of Eigg has its own micro grid built by the residents which works like this.
Would imagine it's the initial cost of seeing all that up, and then the cost of maintenance. For me personally, where do you even start?
It grew organically so there was never a huge cost Really, except when we decided to build a building for The power plant because it was getting out of hand. It’s been a few thousand dollars a year in growth as we add batteries and panels. Also a bit of labor for installation of course, but we handle that in house.
> It grew organically so there was never a huge cost Really,
Ahh, the accounting style of hobby projects. I’m very familiar with this because I do it, too.
Nothing ever feels expensive if you just never add it all up and value your time at $0 because it’s fun.
The total cost of the system so far is about $87k, and operating cost is around 4000 a year (includes equipment amortisation, slow expansion, direct operating costs). In all, for several homes, and a farm it’s very affordable. Getting power hooked up to a single house from the utilities is about $9000, so our buildout is roughly 2x what we might have spent just to get hooked up to the grid.
We do buy carefully, and all the engineering is done by me. We have employees on the farm so much of the labor of installing underground cable etc was “free” (lol).
Still, we are miles ahead of our costs if we were hooked up to the grid (which also would have cost us an additional $20k just for poles to get close, and we still would have had to bury the cables on campus along with the water and data, if we didn’t want ugly poles all over, so that part is a wash)
I spend about 4 hours a week on utilities based projects, mostly engineering monitoring and control systems so that I spend less time working on the utilities. (So, futzing around with electronics because I have an excuse to) it feels like meaningful work that I care about, so that’s nice.
That sounds incredible. This is the first year I've really started digging deep into solar generation and battery storage and it's one big fascinating rabbit hole.
I've looked at it from a bunch of different angles and keep coming to the conclusion that for rural and suburban areas with the space for panels, off-grid solar is the future.
Thank you so much for these posts! It makes me very optimistic about the future.
For the longest time we all watched from the sidelines, hoping that the desire to turn off coal-fired power plants, and research often funded by tax dollars, would get the ball moving on solar. Now that the market has its magic invisible hand on that ball, it seems clear to me we have a path out of this mess.
Rant your stupid “drill baby drill” crap all you want magats, we are going to solar, wind, and fusion our way to a better world, and there is nothing you can do to stop us.
That’s silly, why make it political? If anything the political encroachment came from the green crowd first, cafe standards, EV mandates and the like.
The best way forward has always been to explore all energy avenues, and that will include fossil fuels as well. At least you’ve included nuclear, but left out fission, strangely, which is the best hope of electric generation replacement we currently have.
I’m tired of this team blue for electric (except Tesla now, lol) and team red for oil. They are choices with trade offs, and are friends, not enemies.
No offence, but everything is political. Much of our lives are controlled by laws. These laws are all politically controlled. To say it's silly to make something political, usually suggests your supported political slant is difficult to justify. Trade offs are only possible when the party in charge is willing to work with EVERYONE, we don't have that now. Thus the criticism.
Politics works through division by way of laws. Reduce the laws, reduce the division, and therefore politics.
Fission first! Let's build more nuclear power plants too. We know how to do it, and it's only so expensive because we got scared and stopped. Economies of scale for clean, safe, reliable baseload power.
Turns out, I'm already on fission.
What I've done is tap into an existing fission reactor. It's some distance from my house, but there's a lot of excess energy there leaking out. I put up some collectors to capture it.
Was really quite cheap to do, and I don't have to pay anyone to actually run the reactor.