DIY Solar - some lessons learned for future expansion

[4myr]

I installed a small ongrid DIY system a few years ago. I extended it with extra panels, due to the heat wave last April/May, as I added extra AC's.

And now I am in the process of selling excess electricity to PEA for 2.2 baht per kwh.

My electricity demand is moderate.

 

My future plans are

1) more electricity demand [hotter climate - more AC, extra integrated room/attic ventilation, EV charging],

2) more solar panel production needed to meet the demand,

3) UPS battery storage for an exceptional 4-12 hrs grid outage,

4) and extra battery capacity to earn some bucks, when the time is ripe that due to the succesful EV adoption in Thailand, we get demand based pricing.

 

Given my future plans and looking back how I implemented my DIY solar, the following I would do differently:

 

1) Review your energy use and select where you can to cut down in energy, without sacrificing in comfort or even increase your comfort

 

Examples. I bought 2 years ago my house. I did not like the noise of the water pump, each time I open the tap.

So I made a bypass with valves, as the water pressure from the municipality is high enough to have a comfortable shower.

Only in exceptional cases of low water pressure I turn off the bypass and use the pump.

Use distributed solar panels, buck [=DC/DC] converters, DC pumps and light in your garden as much as possible. This will also save you in AC wiring outdoors.

During this year's heatwave I added extra roof and attic floor insulation. Not yet satisfied with the passive air flow thru soffits. 

 

2) Make use NOW of the PEA/MEA Power Purchase agreement process for small households

 

You can export at 2.2 baht/kwh for a period of 10 years.

The buying program is maxed at 5kw single phase and I believe 10kw for 3 phased.

What does it mean: 1) max out your inverter 2) use a PEA certified inverter 3) do a neat/thorough implementation of your combiner box and earth bonding as this will be inspected 4) Collect all your specs and datasheets of panels and inverter, as you need them to submit them with the online request.

 

You'll need to hire a certified PEA engineer to make the system electrical diagram.

An installation company will charge you between 15-20k baht for this and to help you with the 3-4 month process.

 

If you are more than a moderate PEA user, you are even dependent on this PPA contract to get a good ROI.

My engineer who is helping me with the PPA contract is telling me that PEA Hua Hin is starting to use drones to detect solar panels on roof and will change analog to digital meters.

 

3) Prepare on day 1 for battery extension in the future.

 

This means pay extra for a more expensive PEA certified hybrid inverter that also can work without batteries.
For UPS purposes, the hybrid should be able to output to 2 load panels, the main load and a critical load panel [fridges, small appliances, etc].

Preferably the inverter should work in parallel for future expansion and have a mechanism to control the amount of export electricity to the grid.

 

Add your batteries later, if they further decrease in price or that more affordable second hand EV or telecomm batteries appear in Thailand.

As ambient temperature can get to 35C here in Thailand, and batteries deteriorate with temp above 25C, allocate an insulated "machine" room inside your house for your future batteries close to your hybrid inverter that can be kept below 30C.

 

4) plan your future demand and production on your roof and garden premises

 

You can divide your demand and production in 3 areas:

 

1) grid connected and maxed out at 5kw/10kw production and export, if you want to have a PPA with PEA [item 2].

This entails your hybrid inverter(s) and your batteries for UPS and future demand pricing.

This will be primarily for your house needs, with or without grid tied EV charging

 

2) off grid & distributed in attic and garden e.g. attic fan or pump for pond or rainwater catchment tank.

Depending on your needs, this can entail simple buck converters, or solar charge controllers with used non lithium batteries, depending on the demand time for the appliances

 

3) [future extension]  off/on grid EV charger

This depends on your daily mileage and EV battery size.

The charger is connected to a separate solar panel string dedicated for charging and also to the grid.

You can charge solar for small journeys and when the sun is shining.

There is no need to fully charge in one go, except at the time that you need to make a long journey. 

Having off grid means higher initial cost but also independent from the grid, if the grid has an outage.

I wonder if they already start to sell these chargers in Thailand.

 

[BritManToo]

You are selling electricity back to the PEA, or are trying to sell?

The PEA don't want to buy your electricity, usually they just give their customers the run around.

[lom]

52 minutes ago, BritManToo said:

The PEA don't want to buy your electricity, usually they just give their customers the run around.

PEA is not the big problem, it is EGAT that doesn't want competition.

Edited July 25, 2023 by lom