Sunday, October 23, 2011

The Milestones Keep Coming

A year and a half ago I had this idea of what I wanted for a power solution. It consisted of both AC and DC, being able to take advantage of the Grid when available but allowing for a completely off grid solution with Solar and ample Battery supply.

What I decided on was 400 amp hours of batteries tied to a sophisticated inverter to power plugs and lights (all LED). I was really keen on being able to mix and match each of the plug strings or light strings so that I can either run them off the Inverter or run them off the grid.
 So here is what I designed way back when. I put them in a couple of months ago but never tested it. Hooking up to the grid today and then adding in both batteries and solar and guess what. It worked as advertised, WOW, I was amazed I guess it pays to read the manuals.
You can see the Blue Sky Solar Boost is bringing in a whopping 3.7 amps. I have the panels on the ground for testing but hey they work!
These are two Kyocera 135 Watt panels, tied to my smart inverter Samlex Inverter TN-1500. It both charges the batteries and inverts the solar and manages the grid input and chooses between the two when needed.
I will be keeping my batteries in check with the TriMetric 2025. It is a great status check on how things are working.
As you can see I mounted this in the kitchen so that I can see it every day in my daily activities. I also did a couple of other little projects over the weekend in adding a BBQ and installing my loft window. I am really pleased the way it came out. I got it from Stayton Wood Windows. I noticed Mackenzie now has a blog, you can see it here: Mackenzie Strawn. Good stuff and really appreciate his work.

Oh yea and the BBQ for the deck!
This week I should see my gutters installed and will be finishing up the plumbing. I tripped the pump breaker on the DC panel and heard it hum away, sweet.


  1. Wow.. looks sophisticated but very cool! One question: How would that equipment that's mounted to the outstide of the house fare in below-zero temps? I'm planning a tiny house on wheels for Northern VT...

  2. Looks can be and in this case are very deceiving. At it's core it is really simple, you just need to get past the drawing. To address your question the only thing outside that will be impacted are the batteries. While I could have put them on the inside or in a heated space for most of the Pacific NW I will be fine. If the Cottage goes up into the Mountains in Central Oregon I will have to come up with a different strategy. At 100% charge, a battery will freeze at -77F. At 75%, -35F. At 50%, 10F. At 25%, 5F. At 0% (totally discharged), 20F. Not sure what the freezing temp of panels are but there are no moving parts and with any sun at all they are warm. Hope that helps.

  3. You must dream about this in your sleep :-) looks great!

  4. Bryce, This is fantastic stuff... You are an electrical guru dude... Love the BBQ. Look forward to having a grill out when we are in the NW... I will give you a shout soon

    Be well, sp

  5. Guys, thanks for the shout out. Dream about this in my sleep, too funny. It is the 3am wake up gluing pipe together in my mind.

  6. Okay, more power questions! I was looking at that inverter model and it looks like it has built-in battery charging capabilities. Doesn't that make the blue sky unit unnecessary?

  7. The Blue Sky unit has not played well with the Inverter. I have actually been in conversations with both parties and am going to go direct from Solar Panels to the Inverter. What I am able to gather the Inverter throttles the Blue Sky Unit so that you don't take advantage of the full boost. I will know more over the next couple of weeks but I am not getting all the bang I should out of the panels and I believe it is caused the Blue Sky thinking the batteries are full (Feedback) from the inverter. The Inverter guys recommended the original design, so we will see if the change gives me a better charge.

  8. Hey There-- Any updates on your inverter <-> battery connection? I'm curious to hear if this improved charging at all.


  9. I did remove the Blue Sky unit and it made a big difference and I am now taking full advantage of the charging capacity of the two panels. What was happening was the Blue Sky was reading the Inverter as a "battery" and decided it was fully charged and therefore throttled down it's flow rate. At some point I may bring the Blue Sky back into the equation but for now I am just routing around it.

  10. That's good to hear! How has the system been otherwise in terms of battery bank size and capacity? I've been trying to size out my system and I used a worksheet from that said I needed way way more than I was assuming. I'm basing my system off of yours, especially since you're in the northwest that recieves a similar amount of sun as the northeast. No Air Conditioning, Microwave, Toaster Oven or other big appliances for me. Just my computer, some light bulbs and a Propane Fridge and HW heater. Have you taken your system completely off grid yet?

  11. I have not taken it off grid for more then a day. I just have not done that type of testing as I was waiting till we had some consistent sunshine. I would be interested in knowing what you think your daily load usage would be. Then how many amp hours of batter supply they say you need? I will go over to your solar site and check out what they are saying.

  12. I used this worksheet from and it told me that I needed an unreasonable number of batteries (6 I think) and something like 8 panels!

    I created a spreadsheet with what I think will be my needs. On the high end, I think i'll need around 125 Amp Hours per day. Here's that spreadsheet. I'd appreciate any input!

  13. Wow, this is a bit off in my estimation. I will give you the computer and the stereo at what you rated them. Your pump and fan should be cut to .5 hrs. Lights are your huge issue. If you are using standard DC lights, they draw little, if you are using AC lights like I did then would draw more. Both could be significantly impacted by using LED lights/bulbs. Secondly the way this is calculated it would be like having every light on for six full hours and while I don't know what your window scheme is like. I rarely have more then two lights on at a time, I also have my living room lights on a dimmer and again rarely run them at full power. I would be bet my DC Amp Hours on a daily basis in under two.

    On the bottom half of the spreadsheet I just don't know enough about your propane refrigerator to comment but that seems high, I also don't think it runs 24 hours a day, it should cycle based on ambient temp. My guess is your looking at 16 hours max of run time during a 24 day. That is running 40 minutes out of every hour which seems still too high to me.

  14. Okay, this was really helpful. I am planning on using AC fixtures but LED bulbs. You're right that the 6 hour estimate is way too high. I did a total guess on the propane fridge because I couldn't find any figures from the manufacturer (norcold) on what it will draw when it's running on propane.

    For fan, I plan to have the range exhaust fan on a timer in the winter so it runs for a few minutes every couple of hours. Since I'm doing spray foam, I want to make sure that the air inside the cabin is vented, especially during the winter.

    I made some adjustments based on your comments and now I'm down to 83.6 Amp hours per day. This would mean that I could go two full days with no sunlight before the batteries would dip below 50%. Not bad, especially since I'm planning on going with a similar inverter to yours that can combine grid and battery power.

  15. Hi Bryce!

    I just found your blog here and it is very helpful in trying to figure out a lot of different aspects of the building process. I'm still in the research and planning phase of my tiny house. I've got the exterior all figured out and am now working out all of the interior details (which is WAY more involved).

    I, like most people, want to have my house wired for both on and off grid. Your setup seems the most detailed I can find. The diagram is still confounding me a bit.

    The Blue Sky being out of the equation, the solar panels go directly to the inverter, then out to the lights/outlets (why aren't the lights going through the AC panel and are there individual fuses on those?) and also to the AC electric panel, then out to the outlets. Pretty straight forward. Is that the DC Electrical panel mounted above the Blue Sky and does that wire into the inverter before sending the AC current out to the outlets/lights? Sorry, I have issues with diagrams sometimes...

    Thanks for any clarification you can offer. Its a huge help!


  16. Sorry for the delayed comment, I was traveling. If you replace the Blue Sky for "Batteries" so that you can have lights when the sun is down it might make more sense. I would recommend going to and looking at what they are doing, they are also great folks to talk to about your solar plans.

    To answer your question on the lights each of the power strips do have a fuse in them. If you notice the AC panel is being fed from the grid and the other two light stips are being fed from the inverter i.e. the solar feed. All my lights are LED so that the draw is minimal (no need for big fuse box).

    On the DC panel, it feeds only DC items such as the Water Pump, DC Feed for the fan in the Heater, DC Connection for the Water Heater and some "Cigarette Lighter" adapters I use for charging my phone with car charger plugs, I also have a DC fan in my loft that has the same plug type.

    Hope this helps,

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