Hi. I'm finishing up a house on a small Caribbean Island and need to buy and install two solar hot water heating systems. The sites are ready to go- the panels/tanks will bolt on to flat concrete roofs with unoccluded aspect. Our A/C contractor has installed a couple of systems. I need to choose the system and there is little support here or even online. I can't even find out if direct or indirect heating best for the Caribbean.... We need recommendations for a company with good customer support. I am hoping a budget of 10K for two systems and direct panels(?) for the pool will do it- but don't know even that. Any advice or guidance is most welcome.

I don't have numbers but my intuition is that solar direct hot water is a thing of the past. The price of PV has dropped so dramaticly that I think it is far less initial investment to size a PV system to provide water heating as well as other electrical loads than install thermal solar. If you were going to have PV solar anyway having two different systems seems crazy. Solar water (at least in states - may be looser there) requires copper piping and in northern areas drain down or heat exchanger loops (a direct system for you will be less of course), heat dump method etc. The storage tanks for solar HW are very expensive and standard electric DHW heaters are dirt cheap. Maybe someone out there has crunched the numbers but my gut says go all PV and be done with it. It will also depend on wether or not you're grid tied and can get net metering....

Thanks, Birdman; at last tally, our island(s) had the most expensive electricity in the world as it comes from diesel generators and because those importing the diesel were our politicians, PV systems were illegal until a few months ago (yeah, you read that right- illegal; only the super-rich whole island owners could get special permits.) Grid tie 'soon come'..... We were just getting to the finishing stages on the house when Irma struck in 2017 and most new construction went to the back burner so that the 80 percent of severely damaged domiciles on the island could be fixed. The house was not prepared for PV and I'm not capable of doing it on my own.

Also, the house I'm building is actually two separate buildings connected by a bridge so, yeah- two systems are necessary.

Your input is really appreciated; I just need to heat some water. We may not have taxes, but the elec bill for a 2750 sqft family house here is around $500 a month. Hot water accounts for a big percentage of that bill.

Thanks, Birdman

oh heck, it posted 3x...just deleting

I know the island drill too well - I live on a small island in New England that until last year had local diesel power - we hit a high of $.70 per kWh at one point. Now we have an offshore wind farm and a cable to the mainland - but the electric issue was huge. Your unique situation may make thermal solar work but if your other electric is so high sounds like PV is a no brainer if you can get permitted. Without solar how would you heat DHW? Propane? You would likely need that as back up anyway unless you're willing to have luke warm showers on rainy days.... One thought - use solar PV to power an electric water heater - control it with a timer or a solar sensor so the water heater only draws power when the PV is producing power. Set up that heater as a "pre-heater" for a propane water heater. I don't know if the propane heater could be a tankless - a tankless my not do well receiving preheated water - not sure if they can modulate. Anyway, good luck. Enjoy the island life!

Thank You! Teriffic site.