PV Systems

Some people are already doing some of this in S.A. and it’s very common in Europe. But we have a few tricks up our sleeve specifically for our situation.

Technology is available today in the form of grid tie or bidirectional technology where you can generate your own power to subsidize your consumption. South Africa has some of the greatest potential in the world for solar energy:Solar_land_area

Efficiency is still key as this technology is relatively expensive and it will always be cheaper  to make electricity from coal or nuclear power (excluding costs to the environment). If you have an overwhelming urge to reduce your carbon foot print, you can do this today.
After all money in the bank is not going to give your children a planet to live on.

The ideal system is grid tie where you don’t have batteries and export your excess power to the grid in exchange for credit. This is ideal for residential because you will generate power in the day and take back the credit at night.

Unfortunately this will require the government to approve net metering before it becomes a reality. Also pre paid meters in S.A. are not feed in tariff ready.

It also may not be desirable to pay a feed in tariff only to export a small amount of power.

CHTech energy monitor is net metering ready and is designed to measure self generation and export values. More importantly, it is designed to ensure export does not occur and to control local consumption of energy.

renewable_energy

The bellow graph show power being produced by a 1kW photovoltaic system where more power is being generated than used by the home. Power flows back to the grid and is used by your neighbors.

grid backfeed

This is a great model because residential will supply peak power when industry needs it and they will take it back at nighttime.

The problem is this does not resolve Eskom’s problem with peak demand from residential between 18:00 and 21:00. Eskom nor council have sufficient storage capacity to shift peak sun energy.

Ideally we want to reduce our costs to zero during peak sun and shift the excess energy to residential peak demand time.

To do this we need to store the energy somehow.

A great way to achieve this it to use a island type inverter to isolate your energy production from the utility feed. Excess power is then stored in batteries.

AC-Solar-Systems-PG-8-266x300

This is an excellent option which gives you backup power should the utility fail and you can shift your excess energy to times when you need it or when costs are more expensive.

The drawback is the batteries and island system adds significantly to costs.

So how to do this without exporting to the grid and without batteries?

The solution is to control your loads and store excess energy in geysers for later use. This reduces heating cycles during peak demand and recovers costs by preventing additional hating cycles.

demand management

A heat pump typically heats water to 56°C. For a 100 litter geyser, there is 4kWh of storage power between 56°C and 85°C.
This presents an ideal place to store excess power if you cannot export to the grid.