How about a solar car port on a budget?

[Crossy]

Some of you may remember us building this back in 2015.

 

 

Thread here https://forum.thaivisa.com/topic/481794-housebuilding-thread/?do=findComment&comment=9603407

 

Well the time has finally arrived for me to get my finger out and actually put some solar on the car port.

 

We spoke to our local PEA office who were quite enthusiastic and helpful until we said we didn't want to join the government scheme (IIRC it's called My Solar Roof), the contract was too long and restrictive and the feed-in rate silly.

 

So, we are NOT permitted to spin the meter backwards (net-metering) - At least not officially "don't let the meter reader see it going backwards" said the supervisor (he's not over enamoured with the government scheme either).

 

That along with the costs associated with doing the job "officially", approved inverters, approved installers (no DIY) decided me to do this on the QT.

 

Luckily for us (but not my wallet) we have a standing load of about 1100 Watts (mostly Madam's koi and the freezers), our base consumption hasn't gone below 1000 W for the last year or so (yes, I'm sad, we keep a log - ok the supply monitor does). So 1000W or so of solar would cover the base without the meter going backwards and still produce a visible saving on the power bill.

 

A quick and dirty estimate:-

 

1000W x 5 hours per day = 5 units per day generated. Times 30 days per month = 150 units per month. @ 4 Baht per unit thats 600 Baht per month = 1 case of beer!!

 

Our bill is usually 5500-6000 Baht so 10% reduction, enough to keep Madam's green desires happy.

 

So I went shopping:-

 

4 x 300W solar panels from Global House - On offer at 3,890 Baht a pop.

2 x 600W WVC micro-inverters from AliExpress -  6,500 Baht for the two including duties and VAT.

 

The cost of the "proper" mounting hardware scared me so a visit to our local steel supplier got us 1¹/2" square x 2mm wall thickness at 300 Baht a 6m length. I got 6 pieces, we don't need it all for 4 panels but I'm going to put all the mounting stuff up whilst I'm in roof-climbing mode. So 1800 Baht.

 

We also need some stand-off parts to keep everything off the actual roof, I had some 3" x 1¹/2" x 2mm "in stock" so I made 36 x 100mm long stand off pieces. This steel would probably cost another 400 Baht or so.

 

Washers, self drilling screws, angle fixings, primer and paint are all from stock, but I doubt they would cost more than a grand or so.

 

So, we've spent about 25 grand to save 600 Baht a month. Payback period 41 months, about 3.5 years. I can live with that.

 

I've not decided how to configure the rest of the roof space (there is room for 18 panels) yet, but if back-feeding remains off the option list I expect something with batteries is going to be on the cards (look up hybrid inverters). This would also provide a whole-house UPS facility and render our (noisy) genset redundant.

 

 

Photos as we progress so hopefully all will become clear.

 

Comments always welcome of course (or I wouldn't be posting).

 

 

[Crossy]

Ok some photos.

 

The roof spacers look like this, the large (14mm) hole in the top is to allow the driver to get to the head of the self-drilling bolt that will hold it to the roof (drilled through the tile into the roof steel).

 

 

They will work something like this.

 

 

The steel mounting rails primed ready.

 

 

The 600W inverters, each links to two panels.

 

 

And, just in case you don't know what they look like, 4 x 300W solar panels.

 

 

 

 

 

[tjo o tjim]

Do you run any air conditioning during the late afternoon?  Might be able to pre-cool things and drop another kW off your demand before investing in batteries. Demand-side management is much cheaper than source-side management with batteries. 

[Crossy]

27 minutes ago, tjo o tjim said:

Do you run any air conditioning during the late afternoon?

 

At present, no. But I see where you are coming from.

 

I have ordered (it's not arrived yet) the wireless modem that goes with the inverters. I'm hoping to control the export level from my Arduino based power monitoring system https://forum.thaivisa.com/topic/1022293-new-year-project-power-quality-logger/

 

Someone has already developed a program using Node Red IOT software https://github.com/invite-frey/wvc-inverter which I could possibly adapt parts of to run on the Arduino, it only needs to control the output level of the beasties.

 

 

[taninthai]

Little sketch off how it going to connect up be nice,,how s it connect to main electrics system??

[Crossy]

12 hours ago, taninthai said:

Little sketch off how it going to connect up be nice,,how s it connect to main electrics system??

 

Something like this:-

 

[taninthai]

So your cu is dual feed and box of electronics in inverter stops the panels getting fried...ie the juice can only flow one way...didint realise you can set it up this way????

Edited September 1, 2019 by taninthai

[Crossy]

These little inverters are grid-tie, they sync to the mains and add their power to it.

 

EDIT If you are generating more solar than your house is using you will export to the grid (meter will spin backwards).

 

[Crossy]

Moving right along we start screwing the standoff pieces into position. If this was the house roof I'd put a good splodge of silicon under the part before bolting down, I didn't bother, the odd leak in the car-port won't hurt.

 

 

And the rails get screwed to the stand-offs.

 

[Crossy]

Warning - solar panels are 'kin heavy when you have to lift them onto the roof ????

 

Finally, the 4 panels are in place.

 

 

Panels are fixed using plates and long screws into the rails.

 

 

The plates are actually furniture joining plates with a hole drilled in the centre.

 

 

The ends are secured with angle brackets, from the same place as the furniture plates.

 

 

and

 

 

Next job, inverters, after a cuppa!

 

 

 

 

[johng]

Imagine how much power would be produced if every roof top in Thailand was covered in solar panels..they would (probably) not have to import any electric from neighbouring countries and save billions on gas and oil.

 

[Naam]

neat job Crossy!

[Crossy]

I've hooked up the inverters temporarily to check it's all working, then the heavens opened!

 

More photos tomorrow after work.

 

And I look like a ruddy lobster, well toasted ????

 

[johng]

 
And I look like a ruddy lobster, well toasted [emoji20]
 

Lots of free vitamin D [emoji38]
rub some "harng jorakea" AkA aloe Vera on the burnt bits.

[Crossy]

2 hours ago, johng said:

Imagine how much power would be produced if every roof top in Thailand was covered in solar panels..they would (probably) not have to import any electric from neighbouring countries and save billions on gas and oil.

 

The problem with renewables, and solar in partcular, is that they are often at maximum production when the load is at a minimum and at zero production (at night) when the load is, if not maximum, certainly significant. So either there needs to be conventional backup (which doesn't start quickly and so needs to run inefficiently at small loads during the day) or we need a LOT of storage (a ruddy big battery).

 

Another issue (which may have had a part in the recent UK blackout) is the question of grid inertia. Without the huge flywheel effect of conventional generation (large rotating masses) the grid frequency can vary rapidly and possibly uncontrollably causing renewables (inverter based systems) to drop off-line when they can't follow the variations, reducing the available supply, causing greater frequency instability, causing more renewables to go off-line, causing greater frequency instability ...

 

 

[RideJocky]

You can refrigerate water during the day and use it to chill your ac unit at night


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[Crossy]

10 minutes ago, RideJocky said:

You can refrigerate water during the day and use it to chill your ac unit at night

 

It's actually better to make ice (latent heat of fusion and all that high-school physics stuff you forgot straight after the exam).

 

Make 1 ton of ice and you can have 12,000 BTU of aircon for 1 day.

 

[tjo o tjim]

Would love to mate a 3 or 5-ton condenser to a 10m3 water tank to build a thermal storage system, but doing it with ice and refrigerant gets tricky, and adding glycol on the primary cooling loop too complicated. 

[RideJocky]

Would love to mate a 3 or 5-ton condenser to a 10m3 water tank to build a thermal storage system, but doing it with ice and refrigerant gets tricky, and adding glycol on the primary cooling loop too complicated. 

With enough water, you could just use a cooling tower that only runs when the sun is out.


“Them what bite, gonna get bit. Them what don’t bite, gonna damn sure get ate up” JDH ‘77

[JAS21]

12 hours ago, Crossy said:

 

The problem with renewables, and solar in partcular, is that they are often at maximum production when the load is at a minimum and at zero production (at night) when the load is, if not maximum, certainly significant. So either there needs to be conventional backup (which doesn't start quickly and so needs to run inefficiently at small loads during the day) or we need a LOT of storage (a ruddy big battery).

 

Another issue (which may have had a part in the recent UK blackout) is the question of grid inertia. Without the huge flywheel effect of conventional generation (large rotating masses) the grid frequency can vary rapidly and possibly uncontrollably causing renewables (inverter based systems) to drop off-line when they can't follow the variations, reducing the available supply, causing greater frequency instability, causing more renewables to go off-line, causing greater frequency instability ...

 

 

Yep...parts of Australia, just to name one country...are suffering from an over supply of non synchronous generation. My 'little boy' is part of a team looking into the problem there.

 

The UK runs tighter than in my days as regards 'spinning spare'. So loosing a couple of 'power plants' at basically the same time can and did initiate auto load shedding.

 

I think a few changes may come out of the enquiry.

 

Great topic though Crossy...looked foreward to the post commissioning BBQ and <deleted> Up....

Edited September 1, 2019 by JAS21

[tjo o tjim]

1 hour ago, JAS21 said:

Yep...parts of Australia, just to name one country...are suffering from an over supply of non synchronous generation.

The grid scale batteries are proving themselves out pretty well, and seem to be much more effective than spinning reserve. Nobody can really afford the spinning reserve anymore, and digital control does reduce the amount of it that is required. 

 

Wind seems to pose the most challenges logistically, and that is where the batteries will make the biggest difference. 

[Naam]

6 hours ago, tjo o tjim said:

Would love to mate a 3 or 5-ton condenser to a 10m3 water tank to build a thermal storage system, but doing it with ice and refrigerant gets tricky, and adding glycol on the primary cooling loop too complicated. 

i had plans to use 18ºC well water (4-6 m³/h) for a whole-house chiller serving either 19 individual or three ducted units for zonal purpose (evaporators all refrigerant, condensers 50/50 separated by heatexchanger)  but couldn't find a qualified contractor. when i found a top company it was too late.

 

estimated savings would have been at least 50% electricity cost ~THB 100k/p.a.

 

sooner or later most of my hard working 13 years old units need to be replaced. but being an old fart who cherishes his comfortable lazy life style prevents me to make big changes.  

Edited September 2, 2019 by Naam
no idea what happened :~(

[JAS21]

3 hours ago, tjo o tjim said:

The grid scale batteries are proving themselves out pretty well, and seem to be much more effective than spinning reserve. Nobody can really afford the spinning reserve anymore, and digital control does reduce the amount of it that is required. 

 

Wind seems to pose the most challenges logistically, and that is where the batteries will make the biggest difference. 

I just had a looksee around the internet... just out internet... https://www.drax.com/technology/power-systems-super-subs/

 

and somewhere else I read that the UK will rely somewhat on the Welsh Pump Storage schemes until grid batteries can do the job

 

I remember Ffestiniog the first time around...gee I feel really old now .....

 

 

[tjo o tjim]

5 hours ago, Naam said:

i had plans...

Depending on your priority, humidity or dry bulb temperature, you have a lot of options to reduce your power bill. Chilled water still seems to be hard to pull off here though. 

 

Personally, it is the humidity that kills me, and a number of the easy strategies are marginal. The equivalent of a single 100-ton CalMac ice storage tank would be perfect here, providing an easy way to both cool and de-humidy a home. They have been successful in similar climates before, but it is expensive. 

[tjo o tjim]

3 hours ago, JAS21 said:

I just had a looksee around the internet... just out internet... https://www.drax.com/technology/power-systems-super-subs/

 

and somewhere else I read that the UK will rely somewhat on the Welsh Pump Storage schemes until grid batteries can do the job

 

I remember Ffestiniog the first time around...gee I feel really old now .....

 

 

Batteries give a whole slew of options that things like pumped storage cannot delivere on- the problem without spinning reserve is you need extremely fast response time to stabilize things. Pumped storage is fantastic for long-term energy storage thought. 

[Crossy]

Inverters hung on the car port steel. Cables need tidying ????

 

The inverters are IP65 so should be splash-proof, but chicken that I am I'm going to install perspex rain shields in front of them anyway.

 

http://www.enclosurecompany.com/ip-ratings-explained.php

[johng]

Why not flip them up under the roof then no need for the extra protection.

[Crossy]

6 minutes ago, johng said:

Why not flip them up under the roof then no need for the extra protection.

 

Good thinking Batman. I don't think there's actually space but I will have a look tomorrow.

[Naam]

3 hours ago, tjo o tjim said:

Depending on your priority, humidity or dry bulb temperature, you have a lot of options to reduce your power bill. Chilled water still seems to be hard to pull off here though.  The equivalent of a single 100-ton CalMac ice storage tank would be perfect here...

i respectfully but totally disagree. ẟt between 18ºC well water and an average of 30ºC ambient temperature is a feast for every condensing unit enough to increase efficiency exponentially. no need to play around with an expensive ice producing and storage facility plus the running energy cost for producing ice when sufficient well water is available for pennies via a simple pipe or perhaps an additional well. we are getting ~6m³ with a 1HP pump but are limited to 2HP as tests showed that 2½HP would suck air in the dry season.

 

moreover, our home is not an office building or factory with peak and off peak demands required for energy savings but has a rather constant demand. by the way i like RH in my bedroom <50% and in the living areas 65%.

 

summary: ice in my fruit juice yes, ice for condensing purpose absolutely no.

we are simple poor retired people and can't afford luxuries

[scorecard]

On 9/1/2019 at 3:15 PM, johng said:

Imagine how much power would be produced if every roof top in Thailand was covered in solar panels..they would (probably) not have to import any electric from neighbouring countries and save billions on gas and oil.

 

Let's hope this this happens sooner or later.

 

In the meantime I vote for Crossy as the Solar Champion. 

 

(I have no knowledge at all about the technology however it seems to me it's quickly getting much easier to plan and install. My dream is to eventually instal solar on the house roof and get the family electricity bill down to zero, also meaning zero cost to run 3 to 4 aircons for about 60 - 70% of the year.)