Home built optimizer

[Terry Burnett]

Hi All, I'm a retired electronics technician who felt frustrated at not being able to fully exploit the electricity generated from the solar panels on my roof, installed by ashadegreener. So I developed my own optimizer system which senses the current coming in from the roof and subtracts the current being used in the household and diverts the excess to a heater. It works satisfactorily but is wasteful of energy when it is not needed. I am open to share ideas from anyone who may have ideas about a more efficient mode of use. Thanks, Terry Burnett.

 

[Warpspeed]

Welcome to the Forum Terry.
There are quite a few different approaches to this, but the basic concept of diverting excess solar into heating water is something many of us here are particularly interested in.
So please go ahead, and present your thoughts !

 

[fourtytwo]

Hi All, I'm a retired electronics technician who felt frustrated at not being able to fully exploit the electricity generated from the solar panels on my roof, installed by ashadegreener. So I developed my own optimizer system which senses the current coming in from the roof and subtracts the current being used in the household and diverts the excess to a heater. It works satisfactorily but is wasteful of energy when it is not needed. I am open to share ideas from anyone who may have ideas about a more efficient mode of use. Thanks, Terry Burnett.

I have a similar system in reverse, water heating is priority for 100% of solar!
If you cannot usefully export more then the only options are heat more water or charge a battery.
Space heating is not really useful as in most places when you want the heat in winter solar is at a minimum anyway.

 

[Warpspeed]

Yes, but domestic hot water is usually the intended purpose for most of us here.

The most practical solution is an (excess) solar powered water preheater installed ahead of the main hot water heater.

In winter, it may only raise the incoming water supply by a small amount, but that still reduces the energy requirement for the main water heater.
In mid summer, a preheater can usually meet most if not all of the hot water requirement as water entering the main water heater will already be at the final required temperature, and the extra energy required to keep it hot will be absolutely minimal.

 

[efficientPV]

I assume you are talking about AC from the roof and not DC. I can't imagine how it would be wasteful when not in use. These can be tricky to set up as what you measure may not be how the utility measures it. Are you talking about finding another use once tank is up to temperature. I do proportional DC diversion to heat water off grid and it is quite effective. Share some scheatics.

 

[Warpspeed]

Many quite different ways to do this, all come with various advantages and disadvantages.
That is why I would really like to hear Terry's ideas.

 

[Terry Burnett]

OK I'll explain what mine does. Sensor clamps fitted to the incoming and outgoing leads report the current to the processorm an Arduino Uno. The incoming senses every second so gets every cloud that passes. The outgoing is less accurate. I have to switch off the load for a second every half-minute or so in order to determine the household usage (minus the heater). A simple subtraction determines the usable current. Based on a heater which uses 8 amps the arduino calculates the proportion of a second, in individual cycles that the heater should be turned on for. E.g for 8 amps the semiconductor relay which controls the current is on for 50 cycles during one second i.e. all the time. If 4 amps are generated then it conducts for half a second and so on down to one cycle. This can be seen as a flashing on the heater's neons. The relay conducts only on the zero-crossing point, avoiding transients causing interference or "dirty mains." The beauty of the above is that little heat is generated by the control circuitry. The downside is that it is limited to resistive loads, hence my post.
You may be asking how the electricity meter sees this. Well, by studying of the usage charts it must perceive the usage as smooth or averaged out and not as a series of on/offs, exactly as I wanted. Terry Burnett

 

[kommando]

This version monitors the incoming line 50 times a second and uses the typical UK meter bucket size so that it limits export to near zero. I have one and it works perfectly, only downside is its no longer available in this exact form from the UK.

Mk2PVRouter - Introduction

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

openenergymonitor.org

When I am off grid there is no incoming activity so I switch the heater on/off based on the Sunny Island Frequency shifting.

 

[Warpspeed]

It should be possible to measure the current in the main feed from the street directly, and by comparing that to the phase of the voltage, determine which way power is flowing and how much. Average current will pass through zero at the exact point power flow reverses.

All you need to do is modulate the power to the heating element in some way to keep the current flow into your home at or very close to zero.
No need to do any subtracting or load switching to measure that.

 

[Terry Burnett]

Thanks for these alternatives. Clearly I have much to learn.

 

[upnorthandpersonal]

You could also add a battery. Charge the battery until full, then dump it to the heater. Repeat. You can do this even with a pretty small battery. With a slightly larger one, you can also offset power you buy from the grid since you could make use of a variable tariff and buy when cheap.

 

[Terry Burnett]

So many interesting Idea's com8ng my way. Thanks!