Been meeting to get around to “a post about all the solar stuff” and just keep…not. Had occasion to take/send a few pics the other day (more on the recipient in a moment) and am finally prompted to put something together. This post will be part rant, part philosophy, part informative, and part “ooo look at the cool stuff”…in no particular order, I’m afraid. There’s no TL;DR…either read or don’t. 🙂
Before anything else, if you’re even exploring the idea of maybe making a simple/small/casual solar project, I strongly urge you to get to know Handy Bob. He’s a grumpy, cantankerous, bitter old man (And I consider the man a good friend!)…and has forgotten more in the last 5 minutes about how to actually make solar work than any 5 “big installers” have ever known. You won’t learn how to finance your whole-house grid-tie system (though you might learn…if you bother to read…why grid-tie suuuuuuuuuuuuuuuuucks), and you won’t learn who the “best installers” are (there aren’t any).
But you WILL learn how small (a telescope observatory) to large (he runs his whole home) solar actually works, and what the “magic sauce” is (spoiler alert : There isn’t one. It’s called using your noodle) to maximizing your solar system, and actually getting out of it what it’s capable of.
With that in mind…
We start with a pair of Renogy 100W Monocrystaline panels. These are, for my money, about the best bang for the buck for simple, small, shed/trailer-sized projects. Yes, there are more efficient, lower $/W panels out there, with better warranties and so on. BUT, the Renogy 100W panels are simple, readily available, mountable in a wide variety of configurations, and most importantly…make the power they claim to. All for $129/100W retail, with deals/coupons/discounts frequently available to get them down to $119 or even less at times. (Well…probably not now that the President has decided to punish others for building better products for less money…but we’ll leave that go for now.)
The output from the panels heads inside to the “power center”, where it’s fed into a Bogart Engineering SC2030 charge controller (More on them in a moment) and then out to a pair of Crown CR-235 batteries. This provides 235 Ah total capacity, and the legendary reliability and toughness of the Crowns (Really…not kidding. There’s 2 kinds of batteries in the world for this stuff, gang. Crowns, and the crappy ones) means I’ll continue to get that capacity for many years to come.
Realistically, like any deep cycle battery, a 50% discharge cycle is about as aggressive as I want to be…and i’d prefer to stay at 25-30% in most cases. This leaves me with a very comfortable ~1400 WHr of reliable use in any situation. Given that the obs uses 400-500 WHr on an extreme night of imaging, and I can realistically expect a solid 400Whr of generation even on bad days, I can run indefinitely, and even get 2-3 nights of imaging done if the solar generation fails completely for some reason.
Of course, NONE of this is possible…at all…without knowing what the hell is actually going on with your power system. Handy Bob’s number 1 golden rule is an absolute inarguable truth : You must have a real meter to live successfully on battery power. He then goes on to say :
Buy a Trimetric. Period.
The TriMetric TM2030 is the heart and soul of the system.
First, it monitors power coming in and going out. That sounds simple, but it’s probably the most critical part of your whole system. You simply can not know the health of your batteries, whether your system is performing to its designed criteria, or, most importantly, whether or not you can safely power the items you want to use, without knowing this key bit of information. How much have you used, and how much have you replaced?
The TriMetric goes beyond that, however, and truly manages your battery system. It communicates with several charge controllers (in my case Bogart’s SC2030) and will apply a charging profile tailored to your specific brand, model, and type of battery. Meaning, if the manufacturer recommends your batteries be charged at a certain rate, for a certain time, under certain conditions…the TriMetric will see to it that that happens. If knowing how MUCH power went in and out is the most important data for preserving and maximizing the health of your batteries, then making sure it comes out and goes back in correctly is a close second.
I would be remiss at this point if I didn’t say something about the incredible folks at Bogart Engineering. I’ve had the good fortune to make the acquaintance of the “new” owner, Kedar. He is an uber-geek after my own heart, and is committed to maintaining both the high technical standards and exceptional customer service established by Bogart’s founder, Ralph Hiesey. Indeed, there’s a new toy on the way from him soon, which I will be posting more about soon, that I suspect will blow our collective minds.
Of course you’re all probably wondering about the “bottom line”. Does it work, how well does it work, and what did it cost?
Yes. It works. It works superbly. I can walk outside every single morning, and find my batteries right at the charge percentage I expect. I can, without fail, test them with a hydrometer and see the specific gravity the TriMetric’s SOC meter suggests I should have. I can, without failure, find all 3 cells in both batteries in sync with each other.
In other words : The system does exactly what it was designed to do, does it reliably, and does it right.
Total cost was in the $600-$700 range. That took a bit of shopping, aggressive research, and wheeling and dealing, along with installing everything myself. At full retail, total cost would be in the $900 range. The numbers start going down from there, however, since expanding the system (were I to want to do so) happens for “less money”…that is to say, another panel or more batteries would increase capacity by a larger percentage than increased cost.
All the lessons learned here will be put to use this spring, as I begin adding solar capability to our RV. That project will have its own posts, I’m sure. 🙂