Solar Spare solar energy, how to measure?

[geojay]

We have solar PV panels (1.5kw) and I'm curious about fitting an immersion diverter to use any spare solar energy for heating water rather than sending it back to the grid. Before we do that, I'd like to have an idea if we have sufficient spare solar power for this purpose, if not then it's pointless.
However, I can't see how to measure this... We obviously have the main meter which tells us how much power we consume from the grid and the solar meter (used for the FIT) which tells us how much the panels have produced but this still doesn't let us determine what has been generated but not consumed within the house, i.e. what was surplus to our needs and was exported.

Can anyone suggest a way of ascertaining this?

I'd also be generally interested in getting better visibility of our energy generation and consumption. Our solar inverter is a Fronius IG 20 and while its display gives a power reading, this isn't so useful when it's located in the loft. It would be good to have a remote display or some way of viewing it on a computer or app. Is there any reasonably priced way to achieve this?

 

[fourtytwo]

As far as I understand it, it's however many Kwh is registering on your export meter is available BUT there is a limit to how much energy your tank can absorb governed by the tank thermostat temperature and your hot water usage so it's the latter you really want to measure.

We have a PV hot water system and it normally absorbs 3-4Kwh/day but then there is only two frugal people in the house so a good portion of that is simply heat loss from the tank BUT we don't have to use our oil boiler at all in the summer as a consequence so quite a saving plus it dries all our clothes.

You might be able to work out how much your hot water absorption would be by switching of your boiler and only using the immersion for a few days, like for example powering it for 2 hours whilst nothing else is on in the house and measuring the usage from the electric meter. If your immersion has a plug you might be able to use a Kilowatt or similar plug in meter but monitor it to ensure it doesn't overheat with such a heavy load.

 

[LeeH]

This might be what you are looking for, give them a call to confirm.

1.5kW is a small array, there won’t be many months you will have copious amounts of spare energy. Payback time could be long, I’m shocked at the cost of the diverters.

I would recommend the Apollo Gem, mine has been reliable and seems very well built. Lots of bad press on the iBoosts.

OB115-MOD 100A CT Operated MID Import and Export kWh Electricity Solar PV Meter | eBay

● Solid-Core sensor,330mV ac input 100A. 100A /0.33V. ● MID approved with module B & D certification. ● Reactive power and reactive energy available through RS485 interface. ● Total energy usage can be calculated via 5 different modes.

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[Amit Bajayee]

The excess solar energy can be measured using a solar or energy meter. This device measures the amount of solar electricity panels generate and can accurately read how much spare energy is produced.
To measure excess solar energy, you will need to follow these steps:

1. Install a solar power meter: A solar power meter is a device that is installed between the solar panels and the inverter. It measures the amount of electricity the panels generate and can give you an accurate reading of how much spare energy is produced.
2. Monitor the solar power meter: Once installed, you can start monitoring it to see how much spare energy is produced. The meter will give you a kilowatt-hours (kWh) reading, which is a measure of energy.
3. Calculate the extra energy: To calculate the amount of light energy being produced, you will need to subtract the amount of energy used by your home or business from the total amount of energy generated by the solar panels. The difference is the amount of light energy that is being produced.

By measuring the excess solar energy produced, you can determine whether you have enough excess energy to sell back to the grid or need additional battery storage to store the excess energy for later use.