My DIY Solar Doghouse Project

[ThaiFig]

At the risk of boring everyone with yet another solar project construction thread, I thought I'd document my progress as I move forward, and invite anyone to critique it if they have any constructive suggestions. What I am doing is attempting to move off grid as inexpensively as possible, without sacrificing safety or reliability. My location is central thailand. My power meter is digital.  It's a semi-rural location, not too big but not too small.  I don't have an EV yet, but one day...

 

I recently built my Dobies a dog house which eventually will include a fenced play yard, but for now has overhead cable runs which I tie them to in the evenings.  We're close to a busy road with high speed traffic, so I can't let them run loose like the locals do.  When I enclose the play area, I may add a pergola over the whole structure, which could hold 32 full sized solar panels. That's just me thinking of future expansion possibilities for next year, or after I get an EV.  For now I will just add solar panels to the kennel roof. 

 

The kennel is 2 meters by 8 meters. The roof has a 50 cm overhang on the back and sides, plus 1 meter in the front. Had I originally planned to make a solar roof, I would have made all overhangs 1 meter.  But I came up with the idea after the building was finished. So I have 9 meters x 3.5 meters to play with. But I can let the panels overhang 50 cm++ on the front and back and a couple cm on the two sides, allowing me a total of 16 panels or about 8kw peak using current 555 watt mono panels from Lazada. 

 

These panels are down to almost 3000 baht in price. That's what convinced me solar is now economical, even without selling excess back to PEA.  My electric bill has been 1,000 to 2,000 baht each month, but probably half that usage is at night. So battery storage will be required to meet my off grid goals.

 

[Crossy]

OK quick and dirty sums.

 

8kWP is going to generate about 27kWh per day on average (depends upon weather some days will be a lot better others a lot worse).

 

So that would be about 27 * 30 * 5 = 4,000 Baht's worth of juice per month at current prices!

 

Would your dobies like A/C kennels 

 

If you can get an accurate day/night usage split it would be handy to give an estimate of your storage size, read your meter at 9AM and 5PM.

 

 

 

[ThaiFig]

For an inverter, I chose an all in one hybrid unit. At 8.2 kw, it will handle 16 eventual panels. Yes, I am taking a chance on Chinese quality, but then they do make some of the best and most popular inverters sold today. It is more than big enough to provide my daily energy needs without being pushed to the limit, except when I need it to heat the shower water in the winter. Other than that, I have an inverter AC unit, induction stove, hot pot, fridge, water pump, computer, lights, power tool chargers.  It may struggle to power the AC and water heater with the pump at the same time.

[ThaiFig]

12 minutes ago, Crossy said:

OK quick and dirty sums.

 

8kWP is going to generate about 27kWh per day on average (depends upon weather some days will be a lot better others a lot worse).

 

So that would be about 27 * 30 * 5 = 4,000 Baht's worth of juice per month at current prices!

 

Would your dobies like A/C kennels 

 

If you can get an accurate day/night usage split it would be handy to give an estimate of your storage size, read your meter at 9AM and 5PM.

 

 

 

Washer, dryer, second fridge, second AC, electric oven, table saw, router, fans, irrigation pump... I have a lot of other uses planned which would run up my electric bill in the future.  But I'm mostly sizing it to cover my essential needs during the rainy season.  I'm starting with just 4 panels.  I have 2 electric meters, one for the inverter input, the other for the output.  As I grow the system, the input (grid) side should go to zero. When adding more panels no longer reduces the grid usage, I will switch to expanding the battery pack.

[Crossy]

14 minutes ago, ThaiFig said:

It may struggle to power the AC and water heater with the pump at the same time.

 

Solar water heating is your friend, even if it's only a pre-heat in winter

 

Have a look at @Bandersnatch threads, some great ideas in there.

[patman30]

one thing i would suggest as the roof is nice and low,
make the panels adjustable if you can so you can manually adjust them throughout the year
and if possible either one or two tilted west or possible to adjust if needed
as west facing panels will mean you start using the battery a little later

[ThaiFig]

4 minutes ago, Crossy said:

 

Solar water heating is your friend, even if it's only a pre-heat in winter

 

Have a look at @Bandersnatch threads, some great ideas in there.

Ok, will do, thanks.

[ThaiFig]

Just now, patman30 said:

one thing i would suggest as the roof is nice and low,
make the panels adjustable if you can so you can manually adjust them throughout the year
and if possible either one or two tilted west or possible to adjust if needed
as west facing panels will mean you start using the battery a little later

I did a simulated calculation of the power generation based on Thailand irradiation. I found a very minor difference when I moved the panels around or tilted them more or less, such that I decided to leave them facing NNE at a 6° inclination.  A bigger gain would come from installing an agricultural misting pump under the panels to cool them. We have so many overcast days here in Thailand that make the light non directional, that straight up is as good as any angle, and much less expensive than tiltable framing.

[Encid]

3 hours ago, ThaiFig said:

I did a simulated calculation of the power generation based on Thailand irradiation. I found a very minor difference when I moved the panels around or tilted them more or less, such that I decided to leave them facing NNE at a 6° inclination.  A bigger gain would come from installing an agricultural misting pump under the panels to cool them. We have so many overcast days here in Thailand that make the light non directional, that straight up is as good as any angle, and much less expensive than tiltable framing.

 

I am curious to know what you used to perform your calculations... a software package perhaps?

 

That would be very useful information to have... and enable potential solar system buyers to same lots of baht om system setup.

[ThaiFig]

I used a website, go to https://globalsolaratlas.info/map?c=14.17173,101.635448,8&s=14.155751,101.054109&m=site to set the location, then the click on the link on the right after scrolling down to change the PV system parameters.  It will give you the recommended angles as a default, but you can over-ride them to see what a less than optimum angle will give you.  It can calculate both daily and yearly output.  I was surprised by how little effect the changes had, when dealing with small amounts of tilt.  It may even have a way to set different times of year to calculate monthly averages, but I didn't go that far into it.  It was enough to see that adding a frame to change the angle from 6 degrees incline pointed north northeast to the recommended 16 degrees tilt pointed south didn't give me much extra for the additional expense. The boost from panel cooling has been well documented by others, misting from behind is my idea to minimize crud build up on the face and minimze amount of water needed.

 

 

[ThaiFig]

I am preparing to mount the first four solar panels on the roof so I did some measuring and calculations in preparation for drilling the holes in the roof. It turns out these cement roof tiles have an alternating peak and valley form which repeats every 23 cm. My solar panels are 113.4 cm wide, and the center clamps add 2cm to that, giving me a spacing of 115.4 cm/ panel. 5 * 23 cm yields 115 cm, a nearly perfect match. The roof channels are 10 cm wide, so I can easily move the support holes right or left a cm or two as needed to remain centered in the gap between panels over the course of nine supports for 8 panels.

 

I need to mount the supports in the valleys because the screws don't hold securely enough when only penetrating the top steel layer, and they're not long enough to go through both steel layers of the underlying square tube purlins if they are raised up by the curve of the cement tile peaks. Additionally,  the flat valley floor allows me the small adjustments I need left and right to match the panel spacing.

 

I know this might introduce leaks in the roof but I'll apply silicone around the rubber seals of each screw to hopefully avoid that.  The dogs won't complain if their roof leaks a bit but I may use this method again on my own home roof in the future if it proves satisfactory. 

 

The second lucky coincidence is that mounting 8 panels means I need the width of 40 valleys plus one more for the end clamp of the last panel.  I counted the number of channels in my doghouse roof, and I have exactly 41. Sometimes fate just smiles on you...

 

I will clamp 12 cm long pieces of 2-inch square steel to each vertical hanger bolt to make the support surfaces for each panel. I have the galvanized steel left over from a previous construction project, but only one 6 meter piece. But that's plenty for this railess system. Yes, rails would have been easier, if I'd had enough steel laying around.

 

The photo is a picture of the double ended hanger bolts I'm using.

[Crossy]

Those bolts appear to be intended to hold in wooden beams from the thread form.

 

If not really worried about leaks, then drill in the valleys.

 

Your dobies won't complain about leaks?? Wanna try that with our chihuahuas?? Death by chihuahua!!!

 

[ThaiFig]

Yeah, I couldn't find any metal screw thread versions, but I tested them with double steel layer penetration and they held fine. 

 

My Dobies love water, they complain loudly if I'm hosing off the platform and don't let them attack the spray stream.  I must stop and spray them down or they won't stop barking. My GSD, on the other hand, hates getting even a little bit wet...

[ThaiFig]

I like the idea of a middle support, but in my case the purlins are too far apart and too few in number.  The hanger bolts I got are less than 70 baht each, and very solid, so 4 of them should hold down a panel even in the wind (I hope).  I'll use the standard aluminum clamps that are usually attached to aluminum rails, but I'll  mount them in the middle of 10cm long galvanized box tubing which in turn will be bolted to the angled aluminum that comes with each hanger bolt.  Kind of a Rube Goldberg approach I know.  Drilling mounting holes in the sides of the solar panel isn't an option for me, as that would void the warranty.  With Tier 1 panels, I figure there is at least a 50-50 chance the company will be around to honor their warranty if I need them.   I do like your custom bracket approach, however,  If I hadn't already stocked up on these hanger bolts before finding the forum, I proably would have done something similar.

[007 RED]

3 hours ago, ThaiFig said:

 With Tier 1 panels, I figure there is at least a 50-50 chance the company will be around to honor their warranty if I need them.  

 When I designed the system, I contacted the panel manufacturer (also a Tier 1 company) about drilling holes in the aluminium frame and whether that would affect their warranty.  They responded very quickly and confirmed that provided that the screws, or bolts, which I was proposing to secure the panel to my 'mounting bridges' did not touch, or damage, the under side surface of the white board on which the photo cells are mounted there would not be any problem with them honouring the warranty should a problem be cause by other matters.  Obviously, I have kept that email just in case.

[ThaiFig]

That's too sensible a response 🙂 I would agree that it shouldn't make any difference to the integrity of the panel. But the legal departments of these big corporations are not known for their generous nature or technical expertise.  In short, I wouldn't trust them not to use it as an excuse in a warrantee claim situation.  I'd definitely print out that email were I you!