looking for a smart controlled switch for water heater ......?

[nokar]

hello,
i have a solaredge system.
i heat water via a 50 gallon gas water heater and an upstream 20 gallon electric water heater.
QUESTIONS
1) IN GENERAL, is it more profitable to directly use excess solar power in the electric water heater OR to sell it back to the power company?
i understand there are many factors to consider: cost of electricity, cost of natural gas, amount of hot water used, inefficiency of the solar system.
2) is there a smart controller switch responsive to surplus solar power production to power the electric water heater?

i currently use a timer on the electric water heater between the hours of 10am to 3pm during spring and summer where there is typically surplus power
production. of course during cloudy days there is a deficit production wherein using electricity for water heating would definitely not be economical wrt the gas
water heater operation.

 

[Cheap 4-life]

Depends on how much the power company pays..
when my battery is full (charge controller goes into float) a relay is triggered by my charge controller. This relay is inline with the water heaters power supply from the grid. The water heater turns on and uses the excess solar when the battery is full. I use battery powered grid tie inverters. The inverters power the water heater when the batteries are floating.

 

[efficientPV]

Fact is that a water heater just can't absorb that many excess KWH a day. Many use only 5KWH a day. The higher the temperature, the higher the heat loss. Typically about 1.5KWH a day. With grid tie it is easy to monitor when excess power is going to the grid. Wham bam on off diversion controls don't make sense. Any diversion should be proportional to be effective.

 

[SeaGal]

...
2) is there a smart controller switch responsive to surplus solar power production to power the electric water heater?

Any diversion should be proportional to be effective.

Agree... In the UK there are some commercial products to do that, like this one...

Solar iBoost+ | Solar Immersion Controller - Heater Shop

Buy your next Marlec Solar iBoost from Heater Shop for only £279.98 inc VAT. We have stock and offer free next day delivery. Buy online or call now.

www.heatershop.co.uk

Guess there are equivalents in the USA.

There are also open-source projects to do the same, such as these...

learn/view/pv-diversion/mk2/index.md at master · openenergymonitor/learn

OpenEnergyMonitor learning resources (previously building blocks) - openenergymonitor/learn

github.com

Mk2PVRouter - Introduction

A DIY Constructor’s project to build a Mk2 PV Router system for surplus energy diversion.

mk2pvrouter.co.uk

and

Solar Energy Router to manage overproduction (DIY) – F1ATB

 

[yduR]

hello,
i have a solaredge system.
i heat water via a 50 gallon gas water heater and an upstream 20 gallon electric water heater.
QUESTIONS
1) IN GENERAL, is it more profitable to directly use excess solar power in the electric water heater OR to sell it back to the power company?
i understand there are many factors to consider: cost of electricity, cost of natural gas, amount of hot water used, inefficiency of the solar system.
2) is there a smart controller switch responsive to surplus solar power production to power the electric water heater?

i currently use a timer on the electric water heater between the hours of 10am to 3pm during spring and summer where there is typically surplus power
production. of course during cloudy days there is a deficit production wherein using electricity for water heating would definitely not be economical wrt the gas
water heater operation.

Hello.
The Polska manufacturer has a simple, cheap and efficient solar inverter that heats water in two boilers. Solar Boost MPPT -3000 PRO of 3.5kW