Which inverter for heating water and grid intertie system

[60cents]

OK I'm an absolute newby at this.
I have 10 Sharp NA V115H1 modules
I intend to use 4 of those panels to connect to a Rheem SolarAir 80 gal 240 v hot water tank using an MPPT controller.
The other 6 I plan on using to tie into my electrical system to offset my electric use.
Two separate systems but probably in the same mounting.
I am not going to use a battery system for now. Maybe way later.
I am looking at a Morningstar’s TriStar TS-MPPT 600 V Charge Controller for both systems.
I believe the morning star controller will work well for the hot water heater and probably the grid tie system when I get to setting that up.
But finding info that I can use/understand is not easy.
I really only need the MPPT controller to get started since it will probably be some time before I get to the intertie system.
But Maybe I should be looking a little farther into the future to see if there is a combination of MPPT intertie controller that would eventualy serve both systems.
Boy I could sure use some practical advice.
Thanks

[SunEagle]

Using solar pv panels to heat water is not very cost affective. Better to use a solar thermal panel that circulates the water through it which gets heated by the sun. I own one of those systems and it works great for me.

Instead of splitting up your 10 x 115 watt panels into two small systems I would put all of them toward your house electric needs.

Oh and that Tristar MPPT charger while is pretty good is really for battery charging not a grid tie system.

[60cents]

Hot water with PV panels

Using solar pv panels to heat water is not very cost affective. Better to use a solar thermal panel that circulates the water through it which gets heated by the sun. I own one of those systems and it works great for me.

Instead of splitting up your 10 x 115 watt panels into two small systems I would put all of them toward your house electric needs.

Oh and that Tristar MPPT charger while is pretty good is really for battery charging not a grid tie system.

Thanks for the response SunEagle.

I've done some research on this and found a number of YouTube videos of others who have hooked their dedicated solar panels to a hot water heater, mostly for domestic use. I am looking for infloor heating of a small space 525 sf. And I am just experimenting at the moment. My finished project will probably be a solar thermal system for this small space. Part of my experiment is to augment the PV hot water system with a a heat exchanger on a wood burning stove. And maybe that is all I will ever need.

I also understand that the Tristar charger was designed to charge batteries. I may add a battery back up system to this at a later date but I don't plan to install that now.
I have the idea that I can use a stand alone MPPT charger to heat water in my solar water tank now, mostly as a temporary system, especially if it isn't as efficient as I'm expecting.
I guess that is really my question. Should I buy a separate stand alone MPPT controller and then buy a grid tied controller when I get to installing the rest of my panels? Or buy a combination system that incorporated the MPPT plus a grid tied controller expecting to use both features later on?

Hope that makes sense. Just looking for comments and opinions.

[Naptown]

It will not work well if at all
First off there is no controller needed to connect to a water heater element.

Wire the panels in series to get as close to the element voltage as possible.

Now say the water heater element is the typical 240v 4500w element.
Now you feed say 80 volts into it
It has just turned into a 500 watt element. If the panels can't produce at least that much the voltage will drop as you are moving off the maximum power point of the collectors.
The voltage will drop further until it reaches a balance point which will be substantially lower than the max power the panels can produce.

Your best bet if you are condidering batteries at some point would be a hybrid inverter
If no batteries then just a standard grid tie inverter would be the best and least expensive way to do it

[J.P.M.]

OK I'm an absolute newby at this.
I have 10 Sharp NA V115H1 modules
I intend to use 4 of those panels to connect to a Rheem SolarAir 80 gal 240 v hot water tank using an MPPT controller.
The other 6 I plan on using to tie into my electrical system to offset my electric use.
Two separate systems but probably in the same mounting.
I am not going to use a battery system for now. Maybe way later.
I am looking at a Morningstar’s TriStar TS-MPPT 600 V Charge Controller for both systems.
I believe the morning star controller will work well for the hot water heater and probably the grid tie system when I get to setting that up.
But finding info that I can use/understand is not easy.
I really only need the MPPT controller to get started since it will probably be some time before I get to the intertie system.
But Maybe I should be looking a little farther into the future to see if there is a combination of MPPT intertie controller that would eventualy serve both systems.
Boy I could sure use some practical advice.
Thanks

I'd be with SunEagle on this. For heating H2O, solar thermal collectors are probably something like about 2X+ efficient on an area basis and probably about the same on a cost /area basis as well depending on where you are located and how it's done. A decent solar water heater can have an average yearly system efficiency pushing 30% (mine's about 30-32%). A decent solar PV system can probably get something like 13-16, maybe 17% overall system eff. on an annual basis. However, the care and maint. of a water heater is probably greater than PV, and there are the complications of dealing with the freeze issue(s) - heat exchangers, system type( drianback or others), piping arrangements, etc. For my money, if/when a PV system could do 25% annual eff. I'll replace the water heater w/additional PV. Until then I remind myself that heating water with electricity is sort of like cutting butter with a chain saw.

[60cents]

Electricity math

It will not work well if at all
First off there is no controller needed to connect to a water heater element.

Wire the panels in series to get as close to the element voltage as possible.

Now say the water heater element is the typical 240v 4500w element.
Now you feed say 80 volts into it
It has just turned into a 500 watt element. If the panels can't produce at least that much the voltage will drop as you are moving off the maximum power point of the collectors.
The voltage will drop further until it reaches a balance point which will be substantially lower than the max power the panels can produce.

Your best bet if you are condidering batteries at some point would be a hybrid inverter
If no batteries then just a standard grid tie inverter would be the best and least expensive way to do it

I understand the drop in watts making for a less efficient heating system. Thanks for the info. That helps.
These panels are 115 watts with Voc at 238 and Vpmax at 174 lpmax at 0.661. So if I've done the math right, the watts would drop to around 3200 to the element? Then it should still work but not particularly well?

Here's the YouTube video where I'm getting this idea

http://www.youtube.com/watch?v=R_LStfeC3lI

This video is also connected to this web page

http://techluck.com/

TechLuck apparently makes or distributes its own MPPT charger so they are selling something.

It sounds feasible to me but ???

[bcroe]

I understand the drop in watts making for a less efficient heating system.

These panels are 115 watts with Voc at 238 and Vpmax at 174 lpmax at 0.661. So if I've done the
math right, the watts would drop to around 3200 to the element?

If you are using 4 panels of 115 W, the most you might get is 460 W, and that very rarely. No
amount of manipulation of the voltage & current can change that. To get any useful power, you
need some kind of MPPT controller to match available power to the load. Not sure you can get
one for a heating element; as advised a grid tie setup could do it. Bruce Roe