Help me design system for missionary School in Dominican Republic.

ConvertedConverted Registered Users Posts: 9
Haiti trip is over and now I'm turning to a request from my Brother to help plan and install a larger PV system at a missionary School that my Niece serves at in the DR. It has some unique situations that make it rather complicated.

I visited the site and installed a recording meter on the electrical service. It is a 120/240V 200A service from the local utility. Peak demand during the two days I was there was about 10KWD. Estimating KWH is kinda hard. There is no A/C so loads are ceiling fans in the classrooms, lighting, hood fan in the kitchen, refrigeration, computers in the office, some shop tools in the training shops, etc. There is no utility meter so KWH is not available from the utility. I will try to analyze the recordings of usage and get a close estimate.

Power is VERY unreliable and rolling blackouts are standard procedure daily. There is no rhyme or reason or time schedule. You have power one minute and nothing the next. You can have power for 4 hours one day and nothing the next day and 6 hours the day after that. Most locals that can afford it install inverter chargers and battery banks to ride through the outages.

The school has two inverter chargers and a small battery bank. They only get about 45 minutes of run time after they loose street power. They have installed a 50KW diesel generator which is way oversized but that is what they found so it has been installed. Diesel is very expensive. Costs to rely on the generator are prohibitive.

The goal is to expand the battery bank, add inverters (probably about 20KW), Add a 10KW PV array and end up with a system that would allow them to rarely need to run the generator. Everything needs to be automatic. I.e. loose street power, automatically go on battery power, batteries get to a preset voltage level, automatically start and transfer generator to run school and charge batteries, get street power back automatically switch everything back.

A large international battery company is willing to assist with L16 batteries at reduced cost via in-kind donations. The mission organization has raised about $20,000 so far for the remainder of the project. We have more than enough roof area for a 10KW PV array, generally facing SSW at about 20 degrees.

Let me know what things I should be considering.

I can probably get a 200A automatic transfer switch donated here locally so that might solve a lot of the problem.

Ideas???

Comments

  • BB.BB. Super Moderators, Administrators Posts: 30,651 admin
    Typically, a good place to start is to break up the loads into high power/peak loads and low power/off peak. Measure/estimate everything.

    Use solar/battery/AC inverter to power your off peak loads. And use the Mains/Genset to power the peak loads.

    Conservation can help. Identify heavy loads (refrigeration as an example) -- Perhaps replacing some older equipment with modern/high efficiency equipment.

    Once the loads have been reduced (as best they can), then look at a smaller genset better match to the loads...

    That is where I would start... Trying to get an AC Inverter + Battery Bank to power the entire mission sounds like a very large/potentially expensive project.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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