What can I do to protect my whole-house from power surges and outages? I have two problems: unregulated voltage coming to my house, and my lights flicker when the electric on-demand hot water heater is being used. I want to fix both of these issues with one solution.

I live in Boquete, Panama, where there are frequent brown-outs, power surges, and lightning strikes within a few hundred meters of my house. Usually, the power is only cut off for 5-300 seconds at a time, but it happens about 5-20x/week. I have two floors. Each floor has a 220V Titan on-demand electric hot water heater. Currently, we're renovating the lower floor to be 3 studio vacation rentals, each with their own private bath. They are unoccupied for now, but they will be occupied starting within 30-60 days so I'm hoping to find a solution before then. I have two UPS devices for my internet routers, but I don't want to buy 20+ more of these so that all the high quality appliances and things are protected from surges and outages. Besides, this would not protect the lighting.

I understand just enough about electricity to be dangerous- I've wired an off-grid solar powered cabin I lived in for 4 years. So, any help is appreciated.

Should I get a battery bank and inverter, to setup in-line between the utility and my house, so the utility charges the battery bank, and my house draws directly from the batteries?

Should I only do this for the 220V hot water heaters, and set them up on a separate utility line? (this would be very difficult, because my house is 100% concrete and I don't have the original plans so I have no idea where the wiring is run. Setting up gas hot water heaters is not an option- the water lines are inside, and I can't set up a gas heater indoors.

Ideally, there is some sort of whole-house surge protection with built in small battery bank to supply power for brief periods of time when there is an outage, that I can have installed where the utility power supply enters my house, that can also regulate 220V so the lights no longer flicker when the electric hot water heater is being used. Is this possible? What would it look like? What are my options? I'm asking for design advice, not specific brands.

I'm not interested in the answer: "Ditch those water heaters". Come on, this isn't impossible! For all of you living in first world countries with high power bills and cheap tank heaters... please remember that I am not in your situation. My electricity is $10/mo for a 4K sq ft house because Panama is 80% hydro power, and I can't get tank heaters here. I really want to use these tankless heaters (they're heavenly) and have reliable power, and I'm willing to pay thousands for it if need be.

What are my options? I can order anything online and have it shipped here from the US. I have a local electrician who is very experienced and capable of modifications. The only problem is that everyone here just says 'it's not a big deal, just deal with it the way it is' and nobody knows of any locally available solutions (there are solar pv stores nearby though). However, at the same time, many people have had to replace their $2k+ refrigerators, washing machines, etc due to dangerous surges.. so, we're not okay with that. He said if I find a solution then he'll install it. Help! Thanks in advance.

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    An on-line UPS comes to mind. – winny Oct 2 '17 at 15:53
  • You may not have any right to modify the lines coming into your house, the power company may own them right up until your fuse box, or at least through the meter. – Ron Beyer Oct 2 '17 at 15:55
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    I'd dump those "electric on-demand hot water heaters" for a start... Those have horrendous surge and run amps. – Trevor_G Oct 2 '17 at 16:11
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    That's a plus... but I was more talking about the supply to the house itself. You can have the best bus bars in the house but they will all be to no avail if the supplier uses smaller gauge wires and undersized transformers. – Trevor_G Oct 3 '17 at 17:59
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    You should probably consider applying for a larger service if that is indeed the issue.. esp on a rental unit where you lose control of usage a tad. – Trevor_G Oct 3 '17 at 18:02

Your idea for a large battery backed up UPS that is charged by the power company would be the best solution (most ups systems do provide lightning protection). The size of the inverter would need to be based on your peak load plus a safety factor to prolong the system life. The battery system really would need to be 2-3x to prevent damaging the batteries during discharge I have seen large forklift batteries used in a similar case but longer discharge cycles were needed. In some cases changing the size/ type of main panel can reduce load based flickering, installing a bolt to bus panel where the breakers are bolted directly to the bus reducing some of the voltage drops in the system. The last part would be to request upsized conductors from your service point and possibly change from a conventional meter to CT meter. CT meters take a field reading off of full size bolted conductors where standard meters are like big outlets that the meter plugs into and cause voltage drops, these conversions to bolted connections may help quite a bit I have seen it reduce problems in a medium sized load center on a commercial service.

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I've got two things you can do to fix the problem. Neither will involve giving up your electric instant hot water heaters.

Upgrade your electrical service.

If you have a 200 Amp service now, get an 800 Amp service. The demand draw of those hot water heaters needs to be < 10% of your total capacity if you don't want to see their effect on other circuits.

You will need to pay the electric company to do this however, and it won't be cheap. They will probably have to install a new transformer for you. They'll probably change your plan to treat you like a commercial customer and your bill will go up. But your instant hot water heaters are worth that right?

Separate loads and Install a Tesla Power Wall

Install two new subpanels. One or your instant hot water heaters, and one for the things you don't want to blink out during power outages and surges caused by your hot water heaters. Additionally install a Tesla PowerWall between that second panel and the main panel. That will keep the rest of the building online without disruption.

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  • Wow even here in the U.S. a 400 amp service is usually the largest that can be installed for residential. Even with a larger service there may still be some flickering when large loads are switched on. industrial plants use soft starts to reduce the effects of large motor loads but this won't work with a pure restive load. – Ed Beal Oct 23 '17 at 1:15
  • Yeah, it's extreme, but he's not interested in ditching the instant electric's or hearing it's not possible. He touched on a new utility service already. He can do it. It's just going to cost several thousand dollars in utility work. – Billy C. Oct 23 '17 at 14:23

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