(Comments from Blogger)
2016-07-09 by Mike Halcrow
Have you considered adding wind?
2016-07-10 by Russell Graves
I have. I may add wind, eventually.
Wind is a good bit more complex than solar. It’s harder to put the towers up, and if you want non-toy levels of power, you need a decent diameter turbine and a good pole (a 30-40’ pole and a 10’ diameter turbine are a reasonable minimum for any sort of actual power).
In addition to that, you need a reliable diversion load (resistor banks rated to soak the full power of the turbine, or something similar). You cannot unload a turbine or it will overspeed and destroy itsself - which is different from solar, in which they don’t care if they’re sitting around with no load on them.
Depending on how winter goes, I may get around to doing something with wind, but it’s going to be expensive and complex for what I gain out of it, so it’s pretty far down the list. I’d need to punch pretty good holes in the ground for anchoring it, which isn’t a problem, but tolerable size residential turbines pretty much don’t exist - you’re into build it yourself territory.
2016-07-10 by Ned Funnell
Tried the induction motor to smooth voltage sag yet?
2016-07-11 by Russell Graves
No, haven’t found an old synchronous motor yet. It’s been a low priority.
2016-07-15 by dude mcginty
Being a math geek, I’m partial to sending extra computing power to GIMPS (http://www.mersenne.org/). At least you’re not mining digital currency.
2016-07-15 by Russell Graves
I’d rather play with something a bit less abstract.
2018-03-21 by Unknown
Thanks for the write-up. I’ve been thinking about expanding my solar set-up for awhile and had marked your article as reference.
Can you explain more about battery bank capabilities? Like peak power and average power? You say that for your 8 Trojan batteries: "nameplate energy is 12kWh, though being lead acid, I can’t ever use all of that and shouldn’t drain more than about 2-3kWh out on a regular basis."
What is your standard power usage on a winter and on a summer day?
We are living in metrowest Boston and my main goal from this effort would be back-up power in the case of winter power outages. The key luxuries would be some lights and keeping the refrigerator going (we do have a wood stove for heat). The refrigerator needs 3 or 4kW per day to run.
So if I understand it correctly, I could get, at most, a day of back-up power with 8 Trojans.* Do you have any suggestions about how I could do better? I’d love to get 4 days of back-up power.
* I couldn’t count on them charging back-up on a daily basis. If we had a storm and lost power, there is probably no sun!
2018-03-27 by Russell Graves
If you want backup power for the occasional winter power outage, what you want is a generator. Possibly with a transfer switch and remote start, but you’re probably fine switching and starting manually.
For backup power use, the cycle depth on lead acid matters a lot less. If I were pulling 8-10kWh out of my bank every single day on my current capacity, I’d kill it in short order - they don’t like that. But doing that a few times isn’t a big deal. It’s not like you shouldn’t ever pull more than 3kWh out, but doing that daily will lead to a short cycle life.
In the winter, the main limitation is keeping them from freezing. As lead acid gets more discharged, the freezing point of the electrolyte goes up (as it turns from sulfuric acid into more and more pure water), so keep that in mind.
Since I work during the day, for the most part, I don’t suck that much out of my bank. Idle draw in my office is typically 1.5kWh/day (half network gear, half inverter idle draw), and a light use day for me out there is another 2-3kWh. But most of that comes out of the solar panels - I only draw 1-2kWh out of my battery bank most days.
With my oversize panel bank, I can produce 10kWh on a good day, though I can’t use all of that.
I really, really think the right option for what you want to do (winter, backup power only, after storms) is a generator. Preferably propane (it stores a lot better than gasoline). Wire in a transfer switch outside and go that route.
2019-07-15 by Unknown
A bit old of a thread, but I am curious if you ever got the MHF120200P to report to another wifi station, I want to add remote logging to a off-grid station, and this little doohickie seems just the ticket. THX
2019-07-15 by Russell Graves
No, but you can find other people who have done the work - search around Github and you should find a few projects that decode it. It’s apparently not that tricky.
GitHub - Manawyrm/nRFPowerMonitor: Control a MingHe VAC-1030A wireless power monitor with a Raspberry Pi might be one - I’ve not tried it, though.
2019-07-16 by Unknown
THX, found a few references to tshark and it’s ability to filter on a single station. so I’ll give that a go first.
2019-12-31 by ingenium
since it’s been a couple of years now, can you comment on if you were able to successfully deduct this shed on your taxes? How much did you deduct, and have you been able to do that every year?
2019-12-31 by Russell Graves
I was able to write off the bulk of the construction costs as a business expense in the year I built it.
In terms of ongoing tax benefits, though, I haven’t found many. I have essentially no energy costs out there (about $40/yr in gas/propane for the winter, though that varies year to year), and I haven’t had to replace solar/battery/etc equipment yet. It’s not part of the house, so I can’t really deduct a fraction of the house costs for business purposes either.
If the goal is tax deductions, a room in the house is going to work out a lot better. But if the goal is a nicely isolated workspace for deep work, I cannot recommend my setup highly enough! Maybe just grid tie it, though. And put a decent mini split in, or at least an inverter drive air conditioner. That would improve quality of life significantly, though not enough for me to bother reworking things until my current air conditioner needs replacement.