Solar power questions

[matador007]

I recommend you go with LiFEPo4 (Lithium Ion based) batteries, they keep getting cheaper, and have none of the side effects of Gel, Lead Acid, etc..

I can give you my contact in China for that if needed.

 

What I would do is start with something.  So 3x sets (arrays) of panels, so 1 for each house/dwelling.

Then run that to the equipment area (that will house inverters, batteries, etc..) for each dwelling.  Run that into a AC Panel, and power certain (critical?) pre-calculated loads.

And you would wire AC into the Inverter as well, so the load being pulled from panel would then take from the Inverter in a smart way.  Easy to do these days.

 

Where it (load) takes in order you want (set on inverter), usually being -- 1) live solar energy 2) Batteries until drops to X voltage/% 3) AC from Grid.

 

Then as time goes on, you can expand (or reduce) each dwellings setup as needs go.  So someone moves out, goes on vacation for a while.

 

Just an idea, wish you and your friend all the best.

[shaemus]

On 1/3/2021 at 2:10 PM, SunshineHarvey7 said:

I have a friend who just purchased a 20+ rai of land with 3 dwellings, 1km from his light meter and village. With less than 7 amps of load (based on my clamp-on meter near his main breaker), his voltage drops to around 150 volts! So he's seriously looking at converting to a solar off-grid system rather than putting a lot of money into running high-voltage wire to his property and getting a transformer near his house. So I have a few questions, as I'm trying to help him plan a system. I don't yet have an inventory list of all the stuff he may want to use, so these are general questions to start with.

 

1. If he needs a system that provides more than 5kw, is it possible to connect two or more inverters in parallel to provide the load? If so, what special terms do I look for to find that kind of inverter? (I'm sure I can't do that with just the simple basic inverter.) Is there a separate piece of equipment that is needed to connect the two inverters together and/or balance the load? And would one of the inverters be a "master" inverter that sets the 50hz rate that the other inverter(s) would sync to?

Yes you can have as many inverters as you like, they don't  parallel together as such, they match the wave form to the incoming supply.

Last time i looked anything over 10KWp in Thailand needs a commercial generation licence which is the same as what a solar farm has to apply for. Very time consuming and costly

 

On 1/3/2021 at 2:10 PM, SunshineHarvey7 said:

 

2. Does it make sense to intentionally build a system with smaller inverters so that if one goes down you can fall back on using the good one?

 

Alot of systems use over sized arrays son they gain 100% output for a longer time,

 

On 1/3/2021 at 2:10 PM, SunshineHarvey7 said:

 

3. Regarding batteries, does anyone on this forum have experience using batteries for forklifts or other such equipment? How do they compare with Gel-cells or other deep-cycle batteries?

 

try google

 

On 1/3/2021 at 2:10 PM, SunshineHarvey7 said:

 

4. To get a decent lifetime out of a gel-cell or deep-cycle battery, some people (including https://unboundsolar.com/solar-information/deep-cycle-battery-info) recommend a depth of discharge (DOD) of not more than 50-80% to get a good life and not damage the battery. Am I correct in understanding that this means that I should plan to get 100-160AH of use out of a 200AH battery?

 

Always follow manufactures instructions,

 

 

On 1/3/2021 at 2:10 PM, SunshineHarvey7 said:

 

5. Is there a way to program any of the inverters to shut off or set off an alarm when the batteries get to a certain DOD?

 

 

A decent BMU will do all of this monitoring for you

 

 

On 1/3/2021 at 2:10 PM, SunshineHarvey7 said:

 

6. I would like to suggest to my friend that he start with a system around 3kw or 5kw and then grow the system as needed. (They aren't using any A/C, and most of the cooking would be with propane, so I think such a system may be a good start at least.) Am I correct in assuming that we should plan to grow the system in a "modular" fashion (sorry, maybe there's a better term here), with each "module" having its own set of panels and charge controller and an inverter that can be tied in? (Of course, this relates directly to question #1 above.)

 

See answer 1

On 1/3/2021 at 2:10 PM, SunshineHarvey7 said:

 

These friends are caring for some children and plan to add facilities in the future. So I'm trying to help them plan a system that can grow with their needs. (Another approach is to add new independant solar systems for later buildings, but I assume such an approach isn't necessary.)

 

Thanks in advance for any "light" you can shed on these questions! (I've read quite a bit of the solar threads on the ThaiVisa forum, but please let me know if there's a thread that should answer most/all of these questions.)

hI Harvey

 

I am an electrician and Ex solar installer so i will try and answer some of your questions, i will do so above.

 

 

Basically panels inverters and racking is sold in terms of USD per W, as are battery systems. so once you have a idea of what load you have a need to cater for then you can really only start from there.

 

you could research Redflow batteries, they are made in thailand and use a Zinc bromide solution  and allow for 100% discharge.

 

Obviously you would have already done some research on the potential explosive nature of using lead acids so that needs to be considered when designing your battery room. 

 

 

Shaemus

[Crossy]

1 hour ago, shaemus said:

you could research Redflow batteries, they are made in thailand and use a Zinc bromide solution  and allow for 100% discharge.

 

How do the initial and lifetime costs of zinc bromide compare with the rapidly falling cost of LiFePO4 in usable capacities?

 

[Crossy]

16 minutes ago, Crossy said:

How do the initial and lifetime costs of zinc bromide compare with the rapidly falling cost of LiFePO4 in usable capacities?

 

To answer my own question, this undated article places a price of 12,600 AUD (9,700 USD) on a 10kWh zinc bromide battery. At 48V that's about 210Ah.

 

A similar capacity LiFePO4 battery can be had for about 60,000 THB (2,000 USD). OK it's not in a nice box and can't be re-furbished but unless the zinc bromide price has come down significantly there's only one winner at present.

 

Definitely a technology worth watching.

[shaemus]

8 hours ago, Crossy said:

 

To answer my own question, this undated article places a price of 12,600 AUD (9,700 USD) on a 10kWh zinc bromide battery. At 48V that's about 210Ah

not sure if you are quoting this article, (https://www.solarmarket.com.au/off-grid-systems/battery-pricing)

its dated 2018, so prices well may have moved South since then. The  Redflow has its own set of characteristics, as does each technology. Obviously availability and price is the big one in Thailand. the technologies are there but sometimes very expensive compared to other countries.

 

Shaemus

[Crossy]

15 hours ago, shaemus said:

not sure if you are quoting this article, (https://www.solarmarket.com.au/off-grid-systems/battery-pricing)

its dated 2018,

 

Yeah, the link fell out in the edit somewhere.

 

It wasn't actually that page but another on the same site, same numbers.

 

I've failed to find a supplier in Thailand to get a local price, but, certainly at present, for domestic installations LiFePO4 is supplanting lead-acid as the chemistry of choice.