I'm building a Soar Powered Greenhouse as soon as my snow melt, the design is for a year round system, so I have been doing excessive research being that I am in Northern Ontario Canada. So I'll share a few tidbits that would apply to you as well.
Heating with solar is a fickle business, make the wrong choices and your eating batteries. ANY Resistance device (anything with an element) is not only a power pig but hard on inverters and batteries. You state your in the Pacific North West, ok THAT is a big area and has varied climate zones. The best & most cost effective "Heating" solution is to go Solar Hydronic where you use Solar Water heating Panels, storing the hot water produced in an insulated water tank and then using a low pressure slow flow 12/24V pump attached to a temp sensing thermostat. You can either run 3/4" - 7/8" Pex in the floor (can be buried in the soil (sand layer) and can maintain temps that way, or better, with a proper manifold system, can be distributed underneath the raised beds/tables themselves.
Great Info Here: https://www.builditsolar.com/Projects/WaterHeating/water_heating.htm
-- Propane Heating Tip: I use a Recovered RV Furnace which I took out of a 5 yr old wrecked 20' Camper, it is a Suburban NTS-20 which is direct vent , uses 12VDC and has electronic ignition. With Dual Tank regulator, thermostat and the furnace it cost me $300. Quite efficient and works I use it to keep my Powerhouse / Pumphouse @ 50F/10C throughout winter . I gave it it's own AGM & 100W/12V solar panel. (backed up with my solar system)
Lighting: Ohh boy, another one that's tricky. HPS & MH Lighting is high watt and uses a crap load of power which generates tremendous heat (read waste power), not really practical unless you have a field of solar panels and honking huge batteries. The GOOD News is that LED Grow Lights have blossomed in the past few years and some really remarkable advances have been made in that regard. The price points are wide & varied and so is Quality !!! There is shlock & there is great stuff out there so very cautious & careful research is needed for that, I'm looking but have no conclusions as yet, I am leaning a certain direction but... Most are capable of being switched from Grow Mode to Bloom Mode with the one light fixture, they are power frugal obviously and do not generate excess heat, Decent ones are NOT Cheap, especially those that are tested & certified grow lights that have verified light spectrum tests and such.
Budget: Ohh the fugly one indeed... Above excluded ! $2K USD is a squeeze but not impossible to get a respectable Starter System built that you can expand on. The rule of KISS is best applied here. Starter system, meaning get you up & running "basically" but will need further enhancement and addition to fully complete for purpose.
- The MPP & Growatt all in one units are getting great reviews. These are DIFFERENT than many others, they can have their internal components replaced / repaired if there is a failure (most all in ones don't). Growatt is similar to MPP but with some improvements and more warranty etc but at a slightly higher cost. Will has reviews on both. A 24 Volt System that outputs 120VAC / 4000W would likely fit the initial bill. The MPP & GW's can be "stacked" so you can add another in parallel to increase capacity "properly & cleanly".
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Solar Panels can be bought NEW but now there are many really good deals on used "tested" panels available from various sources. If your in the USA, then by all means 1st place to look is
https://www.santansolar.com/product/ and that will give you some ideas o $$ quickly, many here have gotten panels from them and are tickled pink with them.
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Batteries: Ohh Boy, the DEEP End. This is where "Penny Wise & Dollar Foolish" rules kick in fast & hard. There is ---- Lead Acid of various flavours at various prices point, NONE are created equal ! Anything used for solar is going to be heavy, big and pricey as deep cycle batteries aren't cheap, so proper deep cycle lead will cost you a god chunk of cash up front, 1st timers usually kill them in under 5 years (no matter the intentions and willingness to be good to them). Remember that Lead Batteries can ONLY be discharged to a max of 50% of capacity, else damage & hastened death.
-- LifePo4 has dropped a LOT in prices but still more than Lead, they will easily outlive the Lead and with proper settings will give you 10+ years and maintenance free (maintenance is what get's Fu-barred with lead, good intentions are moot). EX: 8 Pieces 260AH LFP US $678.32 Ship to United States US $415.20
Total US $1,093.52 That makes 24V/280AH 6720 kWh or 2X 12V/280AH 3360 kWh ea. of which you can use 80% very comfortably.
-- GOTCHA'S: The thing everyone forgets when starting to look at this. BOS (Balance of System) which is wiring, fuses & breakers, racking and all the extra bits & pieces to put it together to make it work. This always stings, even when no one wants to admit it !! It's because $5 on this fuse, $20 on that breaker, $40 for that wire & $20 on this, that & the other thing and then next thing you know, death by a thousand small expenses. We Always notice the $500+ purchase but the $20 ones always sneak under the radar till the end of day tally up and you facepalm and say WTF did I get into.
Therefore I always tell people to expect at least add 25% $ ON TOP of major hardware for BOS. This is also where MANY screw up ! Because they are "down to the wire" and end up buying the cheapest of the BOS stuff, crappy parts always end up costing you when you have to replace them and anything they may have damaged. This is one spot with Penny Pinching can really sting you HARD but with cautious & well planned buying you CAN save money and get good quality bits. We here, have such experiences and share where & what to get and what to avoid. Example: Blue Sea Products are Top Quality and $$ but much of it is Bussman Products, which can be bought without BlueSea packaging (like auto sector & others) at considerable savings. There are several things like that.
I Hope that helps a bit.
Time to pour Coffee #2 being 04:45am
Steve
