How big are your water tanks?
Why almost no one doing Solar Thermal?
- Thread starter 1201
- Start date
Pv requires 3-4x the space as thermal for the same output
Nobodybusiness
Collecting the leftovers of the Great Sky Reactor.
Cost less though.
If your stuck in the city on a postage stamp lot then maybe thermal works.
You have 20 acres PV.
efficientPV
Solar Addict
- Joined
- Sep 24, 2019
- Messages
- 1,348
Solar thermal is a worthless asset once the water is hot enough. So, the space is wasted. Solar thermal has lost. Nobody wants it. It only works in industrial scale where water is continuously needed. I've seen lots of solar thermal and five years later they are ripped from the roofs.
Ampster
Renewable Energy Hobbyist
No doubt, but as mentioned above, once the water is heated, the hardware is idle, PV can send to grid for credit or other uses of energy beside heat,
In the same vein pv is worthless when the batteries are full. You size the system for your needs
That's the key. The most efficient use of space might be a small solar-thermal system to pre-heat water (or even boost heat to a higher storage temperature) -- sized at maybe 20% of total need, plus a heat pump water heater. But, once you figure in the (life-cycle) cost for a new system the premium simply isn't warranted (unless you want to fully DIY the solar thermal system).
I start to get the logic of a resistance water heater divert-load for PV.
(That said, here in Hawaii people are still installing thermal hot water systems and being happy with the results. I guess the key factor is not having to worry about freezing temperatures.)
True, but the electricity has more potential opportunistic uses than low-grade heat.
Ampster
Renewable Energy Hobbyist
Like charging an EV as one example. It all depends on where you are are standing, I am on grid so there is always the opportunity to get credit.
Nobodybusiness
Collecting the leftovers of the Great Sky Reactor.
No you can backfeed the grid or use a dump load.
Who is backfeeding the grid when there is no net metering? And net metering is going the way of the dodo.
Nobodybusiness
Collecting the leftovers of the Great Sky Reactor.
No you can backfeed the grid or use a dump load
Still available and dump loads will
Never go away.
In my case, during the heating months, the dump loads are to heat the house and then garage. During the shortest and coldest days of winter there's not enough extra to heat to dump.
As long as my system is working I'll take the free hot water.
As long as my system is working I'll take the free hot water.
efficientPV
Solar Addict
- Joined
- Sep 24, 2019
- Messages
- 1,348
I totally agree. Solar people are the greatest energy wasters in the world. I always have somewhere to send excess energy
My neighbor has a massive system and experienced a leak a few months ago. Sounded like a waterfall and it drained his pool. Flowed into my yard and many others. No thank you. Many other neighbors here in Vegas have leaks with their system as well.
efficientPV
Solar Addict
- Joined
- Sep 24, 2019
- Messages
- 1,348
The nice thing about diversion to resistance is it is immediate in just a fraction of a second. Chart is just a half hour of diversion. Yellow is power.
Vegas seems like about the least hospitable place for such a system given the temperature ranges. I would think a failure sensing system (loss of pressure shutoff) would be mandatory. It also seems like an environment where ground source heat pumps would have taken off, but alas...
What system are you using to divert the excess power?
You can do it with as little as smart relays, as long as you have enough steps to work with. Ideal way is a static controller that is continuously variable, but I doubt anybody is doing that DIY at home.
