1700W of solar will average about 6.8kWh of energy per 'sunny' day. Solar is always good to supplement your energy needs. Particularly if you will remain at anchor for more than 1 day. To calculate the amount of solar energy you will store in one (sunny) day multiply your solar capacity by a factor of 4 i.e 1700W x 4 = 6,800W (6.8kW). This will vary greatly depending on available sunshine and if there is any shading of solar panels