Got excessive PV power? Turn it to thermal

hot_rod

A new pump station from Resol enables excessive PV generated power to power a resistance element and turn it into hot water for DHW or heating loads.

matt_sunwaysolar

Thanks for sharing. With net-metering laws for PV installations becoming less friendly to homeowners, some markets are moving toward "self-consumption" by way of load-shifting.
A lot of other solutions rely on batteries for storage and discharge, which is expensive. This one simply diverts excess electricity to heat, which could certainly be more valuable to a PV system owner than low net-metering payout or tax or adding batteries and controllers to existing systems.
I haven't seen a price-point and it doesn't look like there is an installation history to prove its merit, but all in all, this is pretty cool.

ratio

What does it mean that I A) noticed the heat & domestic loops share a return and am bothered by that?

hot_rod

ratio said:

What does it mean that I A) noticed the heat & domestic loops share a return and am bothered by that?

Good eye, and I don't see a source of CW into the whole system.

matt_sunwaysolar said:

Thanks for sharing. With net-metering laws for PV installations becoming less friendly to homeowners, some markets are moving toward "self-consumption" by way of load-shifting.
A lot of other solutions rely on batteries for storage and discharge, which is expensive. This one simply diverts excess electricity to heat, which could certainly be more valuable to a PV system owner than low net-metering payout or tax or adding batteries and controllers to existing systems.
I haven't seen a price-point and it doesn't look like there is an installation history to prove its merit, but all in all, this is pretty cool.

hot_rod

The editorial in this months SWE claims on May 8, a Sunday low power consumption day in Germany It was sunny, windy average 25°C. Renewable feed in to the grid was approx 90%.

With the coal plants fired and online there was an excess and the EPEX European electricity exchange had negative prices on the spot market, basically paying as much as E.24/kWQH to dump it.

A dilemma.. The German government is considering restricting further expansion of wind and solar and to take wind and solar generation off grid when there is over capacity.

That may be what is driving the concept of these PV to thermal stations.

The same is, will happen here, 2015 saw a 66% increase in residential PV installed 2.099 MW, over 2014 and the 4th consecutive year of over 50% growth. According to EIA data.

Robert O'Brien

Why not just a standard heat pump water heater?

matt_sunwaysolar

Here is the full spec sheet:

http://www.resol.de/Produktdokumente/11210068_FlowSol_E.monen.pdf

Two types of units: one for DHW / one for heating(boiler water/maybe glycol?)

As opposed to a heat pump water heater because it can interface with any (most) existing water heating/ heating unit (rather than buying a new unit when unnecessary) and also directly controls the excess production of electricity from a PV system into heat rather than sending back to the grid.

Without knowing the price point, it's tough to try and form a full opinion. But, I think this is a pretty interesting product. "Self-consumption" for PV systems is coming in mass, so having solutions coming is good; especially if it helps the thermal guys drum up some more work.

hot_rod

"Self-consumption" for PV systems is coming in mass, so having solutions coming is good; especially if it helps the thermal guys drum up some more work.

That was my thought also, with residential solar thermal off 14% or more, this would be a good way to partner with PV installers.

Speaking of heat pump and solar, Styria, Austria is bidding a 450,000 square meter thermal array for a district heating system.

A whooping 1,800,000 cubic meter underground storage will maintain 20- 60°C fluid temperature. Proposed to cover 38% of the heating load for Graz district customers.
The Danish town of Vojens has a 200,000 cubic meter storage.

Thermal powered heat pumps boost that to 85°C, when needed, then into the underground district.

It sits next to a gas/ steam plant as a secondary source.

This will be 3 times the size of the Danish plant, the two Danish plants have a 45 and 65% solar fraction.

keyote

a better solution is to build a hydrogen electrolyzer and make hydrogen gas

SWEI

Hydrogen is tricky stuff -- challenging both to transport and to store.

Thermal storage (when used to span moderate temperature ranges) is simple, predictable, long-lived, and inexpensive (especially when you look at total life cycle costs ). It is generally not compact, lightweight, or mobile.

BobC

Some sodium materials make very good thermal storage mediums.

Bob

SWEI

Ya, for higher temps -- but the containment materials tend to the exotic.

jumper

Nuts to inverters,batteries,&interconnects. Use PV to power AC directly and when house is cool enough use the electricity for stored DHW.

SWEI

Hydronics can fix this. Chill water with PV -> compressor. Dispense as needed over the course of the day (or three, if you have enough well-insulated storage.)

Paul48

Isn't the output of all PV panels DC? You can have micro-inverters on the panels.

hot_rod

Paul48 said:

Isn't the output of all PV panels DC? You can have micro-inverters on the panels.

I think so. The AC panels that you can buy, have the micro inverters built on the back frame.

Paul48

They're nice, but they ain't cheap. They basically double the panel cost, for something smaller than a pack of cigarettes. It's kinda comical, it seems like most of the things you need for PV are 200 and change, each. There's some things that are more, but most are 2 -change. You would think that with the Chinese market-place opening up, this stuff would be dirt cheap now. Sadly, it isn't.

hot_rod

Maybe aimed for the DIY market, plug and play.

jumper

I was thinking about DC motor for compressor.Of course modern DC motors are ECM. That means electronics comparable to inverters. The point is that batteries and interconnects are extra expenses that retard economic viability of PV. DHW storage is much cheaper. Especially in the long run which will include replacing those stinking inverters,batteries,&interconnects.

Paul48

Look to concentrated solar for DHW. Making hot water and running a stirling generator at the same time. A self-contained system that automatically tracks the sun.

hot_rod

A Wind Solar shop not far fro me has these 12VDC elements with integrated control. Germany made, look to be good quality. They sell them mainly for keeping livestock watering tanks from freezing in the winter


I have access to a bunch of 120W 12V Kyoceras for cheap, only 3 years in the sun.

I'm starting a tiny home and may try these for DHW, just for the sheer simplicity compared to a fluid based thermal system. Replace the bottom element in a 30 gallon tank with this 12VDC, leave the 240V up top for boost or non sun days.